2005-04-16 15:20:36 -07:00
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2006-09-04 15:41:16 +02:00
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2005-04-16 15:20:36 -07:00
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2013-05-07 16:19:08 -07:00
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2012-03-05 13:15:27 -08:00
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2005-04-16 15:20:36 -07:00
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2011-11-16 23:57:37 -05:00
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2005-04-16 15:20:36 -07:00
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2012-03-05 13:15:27 -08:00
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2005-04-16 15:20:36 -07:00
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tracing/events: convert block trace points to TRACE_EVENT()
TRACE_EVENT is a more generic way to define tracepoints. Doing so adds
these new capabilities to this tracepoint:
- zero-copy and per-cpu splice() tracing
- binary tracing without printf overhead
- structured logging records exposed under /debug/tracing/events
- trace events embedded in function tracer output and other plugins
- user-defined, per tracepoint filter expressions
...
Cons:
- no dev_t info for the output of plug, unplug_timer and unplug_io events.
no dev_t info for getrq and sleeprq events if bio == NULL.
no dev_t info for rq_abort,...,rq_requeue events if rq->rq_disk == NULL.
This is mainly because we can't get the deivce from a request queue.
But this may change in the future.
- A packet command is converted to a string in TP_assign, not TP_print.
While blktrace do the convertion just before output.
Since pc requests should be rather rare, this is not a big issue.
- In blktrace, an event can have 2 different print formats, but a TRACE_EVENT
has a unique format, which means we have some unused data in a trace entry.
The overhead is minimized by using __dynamic_array() instead of __array().
I've benchmarked the ioctl blktrace vs the splice based TRACE_EVENT tracing:
dd dd + ioctl blktrace dd + TRACE_EVENT (splice)
1 7.36s, 42.7 MB/s 7.50s, 42.0 MB/s 7.41s, 42.5 MB/s
2 7.43s, 42.3 MB/s 7.48s, 42.1 MB/s 7.43s, 42.4 MB/s
3 7.38s, 42.6 MB/s 7.45s, 42.2 MB/s 7.41s, 42.5 MB/s
So the overhead of tracing is very small, and no regression when using
those trace events vs blktrace.
And the binary output of TRACE_EVENT is much smaller than blktrace:
# ls -l -h
-rw-r--r-- 1 root root 8.8M 06-09 13:24 sda.blktrace.0
-rw-r--r-- 1 root root 195K 06-09 13:24 sda.blktrace.1
-rw-r--r-- 1 root root 2.7M 06-09 13:25 trace_splice.out
Following are some comparisons between TRACE_EVENT and blktrace:
plug:
kjournald-480 [000] 303.084981: block_plug: [kjournald]
kjournald-480 [000] 303.084981: 8,0 P N [kjournald]
unplug_io:
kblockd/0-118 [000] 300.052973: block_unplug_io: [kblockd/0] 1
kblockd/0-118 [000] 300.052974: 8,0 U N [kblockd/0] 1
remap:
kjournald-480 [000] 303.085042: block_remap: 8,0 W 102736992 + 8 <- (8,8) 33384
kjournald-480 [000] 303.085043: 8,0 A W 102736992 + 8 <- (8,8) 33384
bio_backmerge:
kjournald-480 [000] 303.085086: block_bio_backmerge: 8,0 W 102737032 + 8 [kjournald]
kjournald-480 [000] 303.085086: 8,0 M W 102737032 + 8 [kjournald]
getrq:
kjournald-480 [000] 303.084974: block_getrq: 8,0 W 102736984 + 8 [kjournald]
kjournald-480 [000] 303.084975: 8,0 G W 102736984 + 8 [kjournald]
bash-2066 [001] 1072.953770: 8,0 G N [bash]
bash-2066 [001] 1072.953773: block_getrq: 0,0 N 0 + 0 [bash]
rq_complete:
konsole-2065 [001] 300.053184: block_rq_complete: 8,0 W () 103669040 + 16 [0]
konsole-2065 [001] 300.053191: 8,0 C W 103669040 + 16 [0]
ksoftirqd/1-7 [001] 1072.953811: 8,0 C N (5a 00 08 00 00 00 00 00 24 00) [0]
ksoftirqd/1-7 [001] 1072.953813: block_rq_complete: 0,0 N (5a 00 08 00 00 00 00 00 24 00) 0 + 0 [0]
rq_insert:
kjournald-480 [000] 303.084985: block_rq_insert: 8,0 W 0 () 102736984 + 8 [kjournald]
kjournald-480 [000] 303.084986: 8,0 I W 102736984 + 8 [kjournald]
Changelog from v2 -> v3:
- use the newly introduced __dynamic_array().
Changelog from v1 -> v2:
- use __string() instead of __array() to minimize the memory required
to store hex dump of rq->cmd().
- support large pc requests.
- add missing blk_fill_rwbs_rq() in block_rq_requeue TRACE_EVENT.
- some cleanups.
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
LKML-Reference: <4A2DF669.5070905@cn.fujitsu.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2009-06-09 13:43:05 +08:00
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blk-throttle: add a simple idle detection
A cgroup gets assigned a low limit, but the cgroup could never dispatch
enough IO to cross the low limit. In such case, the queue state machine
will remain in LIMIT_LOW state and all other cgroups will be throttled
according to low limit. This is unfair for other cgroups. We should
treat the cgroup idle and upgrade the state machine to lower state.
We also have a downgrade logic. If the state machine upgrades because of
cgroup idle (real idle), the state machine will downgrade soon as the
cgroup is below its low limit. This isn't what we want. A more
complicated case is cgroup isn't idle when queue is in LIMIT_LOW. But
when queue gets upgraded to lower state, other cgroups could dispatch
more IO and this cgroup can't dispatch enough IO, so the cgroup is below
its low limit and looks like idle (fake idle). In this case, the queue
should downgrade soon. The key to determine if we should do downgrade is
to detect if cgroup is truely idle.
Unfortunately it's very hard to determine if a cgroup is real idle. This
patch uses the 'think time check' idea from CFQ for the purpose. Please
note, the idea doesn't work for all workloads. For example, a workload
with io depth 8 has disk utilization 100%, hence think time is 0, eg,
not idle. But the workload can run higher bandwidth with io depth 16.
Compared to io depth 16, the io depth 8 workload is idle. We use the
idea to roughly determine if a cgroup is idle.
We treat a cgroup idle if its think time is above a threshold (by
default 1ms for SSD and 100ms for HD). The idea is think time above the
threshold will start to harm performance. HD is much slower so a longer
think time is ok.
The patch (and the latter patches) uses 'unsigned long' to track time.
We convert 'ns' to 'us' with 'ns >> 10'. This is fast but loses
precision, should not a big deal.
Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2017-03-27 10:51:41 -07:00
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2008-11-26 11:59:56 +01:00
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2008-12-23 12:42:54 +01:00
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2005-04-16 15:20:36 -07:00
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2016-07-19 11:28:42 +02:00
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2005-04-16 15:20:36 -07:00
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2008-06-17 18:59:56 +02:00
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2012-09-06 15:35:01 -07:00
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2005-04-16 15:20:36 -07:00
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2008-12-10 15:35:05 +01:00
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2012-08-09 15:19:25 +02:00
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2012-10-22 21:53:36 +02:00
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2008-12-10 15:35:05 +01:00
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2010-01-19 14:07:09 +01:00
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2008-12-10 15:35:05 +01:00
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2012-10-22 21:53:36 +02:00
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2012-08-09 15:19:25 +02:00
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2012-10-22 21:53:36 +02:00
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2012-08-09 15:19:25 +02:00
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2008-12-10 15:35:05 +01:00
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2012-10-22 21:53:36 +02:00
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2012-08-09 15:19:25 +02:00
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2008-12-10 15:35:05 +01:00
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2014-03-28 15:51:55 -04:00
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2008-12-10 15:35:05 +01:00
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2008-06-30 20:04:41 +02:00
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2012-10-12 15:29:33 -07:00
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2008-12-10 15:35:05 +01:00
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2016-07-19 11:28:42 +02:00
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2008-12-10 15:35:05 +01:00
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2016-07-19 11:28:42 +02:00
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2012-10-12 15:29:33 -07:00
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2016-07-19 11:28:42 +02:00
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2008-12-10 15:35:05 +01:00
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2012-10-12 15:29:33 -07:00
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2005-04-16 15:20:36 -07:00
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2008-12-11 11:53:43 +01:00
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2016-07-19 11:28:42 +02:00
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2008-12-11 11:53:43 +01:00
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2012-10-12 15:29:33 -07:00
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2008-12-11 11:53:43 +01:00
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2015-11-06 16:28:21 -08:00
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2008-12-11 11:53:43 +01:00
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2008-09-11 13:17:37 +02:00
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2008-12-11 11:53:43 +01:00
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2008-09-11 13:17:37 +02:00
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2008-12-11 11:53:43 +01:00
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2005-04-16 15:20:36 -07:00
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2008-09-11 13:17:37 +02:00
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2015-11-06 16:28:21 -08:00
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2008-12-11 11:53:43 +01:00
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2008-09-11 13:17:37 +02:00
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2008-12-11 11:53:43 +01:00
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2015-11-06 16:28:21 -08:00
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2016-07-19 11:28:42 +02:00
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2008-12-11 11:53:43 +01:00
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2016-07-19 11:28:42 +02:00
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2005-04-16 15:20:36 -07:00
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2017-06-28 15:30:13 -06:00
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2005-04-16 15:20:36 -07:00
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2012-09-06 15:35:00 -07:00
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2017-06-28 15:30:13 -06:00
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2008-06-30 20:04:41 +02:00
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2012-09-06 15:35:00 -07:00
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2017-06-28 15:30:13 -06:00
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2012-09-06 15:35:00 -07:00
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2016-07-19 11:28:42 +02:00
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2012-09-06 15:35:00 -07:00
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2008-12-10 15:35:05 +01:00
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2012-09-06 15:35:00 -07:00
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2005-09-06 15:16:42 -07:00
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2017-06-28 15:30:13 -06:00
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2016-11-22 08:57:21 -07:00
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2005-04-16 15:20:36 -07:00
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2007-07-18 13:14:03 +02:00
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2015-04-17 16:15:18 -06:00
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2015-04-17 16:23:59 -06:00
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2016-11-22 08:57:21 -07:00
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2005-04-16 15:20:36 -07:00
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2009-09-26 16:19:21 +02:00
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2005-04-16 15:20:36 -07:00
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2012-09-06 15:34:58 -07:00
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2017-06-28 15:30:13 -06:00
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2012-09-06 15:34:58 -07:00
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2015-07-20 15:29:37 +02:00
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2015-04-17 16:15:18 -06:00
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2012-09-06 15:34:58 -07:00
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2016-03-11 17:34:51 +01:00
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2013-11-23 18:34:15 -08:00
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2015-07-20 15:29:37 +02:00
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2017-06-03 09:38:06 +02:00
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2013-11-23 18:34:15 -08:00
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2016-03-11 17:34:51 +01:00
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2013-11-23 18:34:15 -08:00
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2014-04-20 16:03:31 -07:00
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2013-11-23 18:34:15 -08:00
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2015-04-17 16:15:18 -06:00
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2013-11-23 18:34:15 -08:00
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block: Avoid deadlocks with bio allocation by stacking drivers
Previously, if we ever try to allocate more than once from the same bio
set while running under generic_make_request() (i.e. a stacking block
driver), we risk deadlock.
This is because of the code in generic_make_request() that converts
recursion to iteration; any bios we submit won't actually be submitted
(so they can complete and eventually be freed) until after we return -
this means if we allocate a second bio, we're blocking the first one
from ever being freed.
Thus if enough threads call into a stacking block driver at the same
time with bios that need multiple splits, and the bio_set's reserve gets
used up, we deadlock.
This can be worked around in the driver code - we could check if we're
running under generic_make_request(), then mask out __GFP_WAIT when we
go to allocate a bio, and if the allocation fails punt to workqueue and
retry the allocation.
But this is tricky and not a generic solution. This patch solves it for
all users by inverting the previously described technique. We allocate a
rescuer workqueue for each bio_set, and then in the allocation code if
there are bios on current->bio_list we would be blocking, we punt them
to the rescuer workqueue to be submitted.
This guarantees forward progress for bio allocations under
generic_make_request() provided each bio is submitted before allocating
the next, and provided the bios are freed after they complete.
Note that this doesn't do anything for allocation from other mempools.
Instead of allocating per bio data structures from a mempool, code
should use bio_set's front_pad.
Tested it by forcing the rescue codepath to be taken (by disabling the
first GFP_NOWAIT) attempt, and then ran it with bcache (which does a lot
of arbitrary bio splitting) and verified that the rescuer was being
invoked.
Signed-off-by: Kent Overstreet <koverstreet@google.com>
CC: Jens Axboe <axboe@kernel.dk>
Acked-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Muthukumar Ratty <muthur@gmail.com>
2012-09-10 14:33:46 -07:00
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2017-06-18 14:38:57 +10:00
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block: Avoid deadlocks with bio allocation by stacking drivers
Previously, if we ever try to allocate more than once from the same bio
set while running under generic_make_request() (i.e. a stacking block
driver), we risk deadlock.
This is because of the code in generic_make_request() that converts
recursion to iteration; any bios we submit won't actually be submitted
(so they can complete and eventually be freed) until after we return -
this means if we allocate a second bio, we're blocking the first one
from ever being freed.
Thus if enough threads call into a stacking block driver at the same
time with bios that need multiple splits, and the bio_set's reserve gets
used up, we deadlock.
This can be worked around in the driver code - we could check if we're
running under generic_make_request(), then mask out __GFP_WAIT when we
go to allocate a bio, and if the allocation fails punt to workqueue and
retry the allocation.
But this is tricky and not a generic solution. This patch solves it for
all users by inverting the previously described technique. We allocate a
rescuer workqueue for each bio_set, and then in the allocation code if
there are bios on current->bio_list we would be blocking, we punt them
to the rescuer workqueue to be submitted.
This guarantees forward progress for bio allocations under
generic_make_request() provided each bio is submitted before allocating
the next, and provided the bios are freed after they complete.
Note that this doesn't do anything for allocation from other mempools.
Instead of allocating per bio data structures from a mempool, code
should use bio_set's front_pad.
Tested it by forcing the rescue codepath to be taken (by disabling the
first GFP_NOWAIT) attempt, and then ran it with bcache (which does a lot
of arbitrary bio splitting) and verified that the rescuer was being
invoked.
Signed-off-by: Kent Overstreet <koverstreet@google.com>
CC: Jens Axboe <axboe@kernel.dk>
Acked-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Muthukumar Ratty <muthur@gmail.com>
2012-09-10 14:33:46 -07:00
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2017-03-10 17:00:47 +11:00
|
|
|
|
block: Avoid deadlocks with bio allocation by stacking drivers
Previously, if we ever try to allocate more than once from the same bio
set while running under generic_make_request() (i.e. a stacking block
driver), we risk deadlock.
This is because of the code in generic_make_request() that converts
recursion to iteration; any bios we submit won't actually be submitted
(so they can complete and eventually be freed) until after we return -
this means if we allocate a second bio, we're blocking the first one
from ever being freed.
Thus if enough threads call into a stacking block driver at the same
time with bios that need multiple splits, and the bio_set's reserve gets
used up, we deadlock.
This can be worked around in the driver code - we could check if we're
running under generic_make_request(), then mask out __GFP_WAIT when we
go to allocate a bio, and if the allocation fails punt to workqueue and
retry the allocation.
But this is tricky and not a generic solution. This patch solves it for
all users by inverting the previously described technique. We allocate a
rescuer workqueue for each bio_set, and then in the allocation code if
there are bios on current->bio_list we would be blocking, we punt them
to the rescuer workqueue to be submitted.
This guarantees forward progress for bio allocations under
generic_make_request() provided each bio is submitted before allocating
the next, and provided the bios are freed after they complete.
Note that this doesn't do anything for allocation from other mempools.
Instead of allocating per bio data structures from a mempool, code
should use bio_set's front_pad.
Tested it by forcing the rescue codepath to be taken (by disabling the
first GFP_NOWAIT) attempt, and then ran it with bcache (which does a lot
of arbitrary bio splitting) and verified that the rescuer was being
invoked.
Signed-off-by: Kent Overstreet <koverstreet@google.com>
CC: Jens Axboe <axboe@kernel.dk>
Acked-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Muthukumar Ratty <muthur@gmail.com>
2012-09-10 14:33:46 -07:00
|
|
|
|
2017-03-10 17:00:47 +11:00
|
|
|
|
block: Avoid deadlocks with bio allocation by stacking drivers
Previously, if we ever try to allocate more than once from the same bio
set while running under generic_make_request() (i.e. a stacking block
driver), we risk deadlock.
This is because of the code in generic_make_request() that converts
recursion to iteration; any bios we submit won't actually be submitted
(so they can complete and eventually be freed) until after we return -
this means if we allocate a second bio, we're blocking the first one
from ever being freed.
Thus if enough threads call into a stacking block driver at the same
time with bios that need multiple splits, and the bio_set's reserve gets
used up, we deadlock.
This can be worked around in the driver code - we could check if we're
running under generic_make_request(), then mask out __GFP_WAIT when we
go to allocate a bio, and if the allocation fails punt to workqueue and
retry the allocation.
But this is tricky and not a generic solution. This patch solves it for
all users by inverting the previously described technique. We allocate a
rescuer workqueue for each bio_set, and then in the allocation code if
there are bios on current->bio_list we would be blocking, we punt them
to the rescuer workqueue to be submitted.
This guarantees forward progress for bio allocations under
generic_make_request() provided each bio is submitted before allocating
the next, and provided the bios are freed after they complete.
Note that this doesn't do anything for allocation from other mempools.
Instead of allocating per bio data structures from a mempool, code
should use bio_set's front_pad.
Tested it by forcing the rescue codepath to be taken (by disabling the
first GFP_NOWAIT) attempt, and then ran it with bcache (which does a lot
of arbitrary bio splitting) and verified that the rescuer was being
invoked.
Signed-off-by: Kent Overstreet <koverstreet@google.com>
CC: Jens Axboe <axboe@kernel.dk>
Acked-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Muthukumar Ratty <muthur@gmail.com>
2012-09-10 14:33:46 -07:00
|
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|
2017-03-10 17:00:47 +11:00
|
|
|
|
|
|
|
|
|
|
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|
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|
|
|
|
block: Avoid deadlocks with bio allocation by stacking drivers
Previously, if we ever try to allocate more than once from the same bio
set while running under generic_make_request() (i.e. a stacking block
driver), we risk deadlock.
This is because of the code in generic_make_request() that converts
recursion to iteration; any bios we submit won't actually be submitted
(so they can complete and eventually be freed) until after we return -
this means if we allocate a second bio, we're blocking the first one
from ever being freed.
Thus if enough threads call into a stacking block driver at the same
time with bios that need multiple splits, and the bio_set's reserve gets
used up, we deadlock.
This can be worked around in the driver code - we could check if we're
running under generic_make_request(), then mask out __GFP_WAIT when we
go to allocate a bio, and if the allocation fails punt to workqueue and
retry the allocation.
But this is tricky and not a generic solution. This patch solves it for
all users by inverting the previously described technique. We allocate a
rescuer workqueue for each bio_set, and then in the allocation code if
there are bios on current->bio_list we would be blocking, we punt them
to the rescuer workqueue to be submitted.
This guarantees forward progress for bio allocations under
generic_make_request() provided each bio is submitted before allocating
the next, and provided the bios are freed after they complete.
Note that this doesn't do anything for allocation from other mempools.
Instead of allocating per bio data structures from a mempool, code
should use bio_set's front_pad.
Tested it by forcing the rescue codepath to be taken (by disabling the
first GFP_NOWAIT) attempt, and then ran it with bcache (which does a lot
of arbitrary bio splitting) and verified that the rescuer was being
invoked.
Signed-off-by: Kent Overstreet <koverstreet@google.com>
CC: Jens Axboe <axboe@kernel.dk>
Acked-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Muthukumar Ratty <muthur@gmail.com>
2012-09-10 14:33:46 -07:00
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2005-04-16 15:20:36 -07:00
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2017-10-16 11:01:00 -07:00
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2005-04-16 15:20:36 -07:00
|
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2010-01-15 12:05:07 +02:00
|
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2005-04-16 15:20:36 -07:00
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2012-09-06 15:35:01 -07:00
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2015-11-06 16:28:21 -08:00
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2012-09-06 15:35:01 -07:00
|
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|
|
block: Avoid deadlocks with bio allocation by stacking drivers
Previously, if we ever try to allocate more than once from the same bio
set while running under generic_make_request() (i.e. a stacking block
driver), we risk deadlock.
This is because of the code in generic_make_request() that converts
recursion to iteration; any bios we submit won't actually be submitted
(so they can complete and eventually be freed) until after we return -
this means if we allocate a second bio, we're blocking the first one
from ever being freed.
Thus if enough threads call into a stacking block driver at the same
time with bios that need multiple splits, and the bio_set's reserve gets
used up, we deadlock.
This can be worked around in the driver code - we could check if we're
running under generic_make_request(), then mask out __GFP_WAIT when we
go to allocate a bio, and if the allocation fails punt to workqueue and
retry the allocation.
But this is tricky and not a generic solution. This patch solves it for
all users by inverting the previously described technique. We allocate a
rescuer workqueue for each bio_set, and then in the allocation code if
there are bios on current->bio_list we would be blocking, we punt them
to the rescuer workqueue to be submitted.
This guarantees forward progress for bio allocations under
generic_make_request() provided each bio is submitted before allocating
the next, and provided the bios are freed after they complete.
Note that this doesn't do anything for allocation from other mempools.
Instead of allocating per bio data structures from a mempool, code
should use bio_set's front_pad.
Tested it by forcing the rescue codepath to be taken (by disabling the
first GFP_NOWAIT) attempt, and then ran it with bcache (which does a lot
of arbitrary bio splitting) and verified that the rescuer was being
invoked.
Signed-off-by: Kent Overstreet <koverstreet@google.com>
CC: Jens Axboe <axboe@kernel.dk>
Acked-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Muthukumar Ratty <muthur@gmail.com>
2012-09-10 14:33:46 -07:00
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2012-09-06 15:35:01 -07:00
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2017-03-23 13:24:55 +03:00
|
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|
2005-04-16 15:20:36 -07:00
|
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|
|
block: Avoid deadlocks with bio allocation by stacking drivers
Previously, if we ever try to allocate more than once from the same bio
set while running under generic_make_request() (i.e. a stacking block
driver), we risk deadlock.
This is because of the code in generic_make_request() that converts
recursion to iteration; any bios we submit won't actually be submitted
(so they can complete and eventually be freed) until after we return -
this means if we allocate a second bio, we're blocking the first one
from ever being freed.
Thus if enough threads call into a stacking block driver at the same
time with bios that need multiple splits, and the bio_set's reserve gets
used up, we deadlock.
This can be worked around in the driver code - we could check if we're
running under generic_make_request(), then mask out __GFP_WAIT when we
go to allocate a bio, and if the allocation fails punt to workqueue and
retry the allocation.
But this is tricky and not a generic solution. This patch solves it for
all users by inverting the previously described technique. We allocate a
rescuer workqueue for each bio_set, and then in the allocation code if
there are bios on current->bio_list we would be blocking, we punt them
to the rescuer workqueue to be submitted.
This guarantees forward progress for bio allocations under
generic_make_request() provided each bio is submitted before allocating
the next, and provided the bios are freed after they complete.
Note that this doesn't do anything for allocation from other mempools.
Instead of allocating per bio data structures from a mempool, code
should use bio_set's front_pad.
Tested it by forcing the rescue codepath to be taken (by disabling the
first GFP_NOWAIT) attempt, and then ran it with bcache (which does a lot
of arbitrary bio splitting) and verified that the rescuer was being
invoked.
Signed-off-by: Kent Overstreet <koverstreet@google.com>
CC: Jens Axboe <axboe@kernel.dk>
Acked-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Muthukumar Ratty <muthur@gmail.com>
2012-09-10 14:33:46 -07:00
|
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|
|
2012-09-06 15:35:01 -07:00
|
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|
|
|
|
|
|
|
2009-02-21 11:16:36 +01:00
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|
2009-04-15 19:50:51 +02:00
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2012-09-06 15:35:01 -07:00
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2014-10-03 17:27:12 -04:00
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|
block: Avoid deadlocks with bio allocation by stacking drivers
Previously, if we ever try to allocate more than once from the same bio
set while running under generic_make_request() (i.e. a stacking block
driver), we risk deadlock.
This is because of the code in generic_make_request() that converts
recursion to iteration; any bios we submit won't actually be submitted
(so they can complete and eventually be freed) until after we return -
this means if we allocate a second bio, we're blocking the first one
from ever being freed.
Thus if enough threads call into a stacking block driver at the same
time with bios that need multiple splits, and the bio_set's reserve gets
used up, we deadlock.
This can be worked around in the driver code - we could check if we're
running under generic_make_request(), then mask out __GFP_WAIT when we
go to allocate a bio, and if the allocation fails punt to workqueue and
retry the allocation.
But this is tricky and not a generic solution. This patch solves it for
all users by inverting the previously described technique. We allocate a
rescuer workqueue for each bio_set, and then in the allocation code if
there are bios on current->bio_list we would be blocking, we punt them
to the rescuer workqueue to be submitted.
This guarantees forward progress for bio allocations under
generic_make_request() provided each bio is submitted before allocating
the next, and provided the bios are freed after they complete.
Note that this doesn't do anything for allocation from other mempools.
Instead of allocating per bio data structures from a mempool, code
should use bio_set's front_pad.
Tested it by forcing the rescue codepath to be taken (by disabling the
first GFP_NOWAIT) attempt, and then ran it with bcache (which does a lot
of arbitrary bio splitting) and verified that the rescuer was being
invoked.
Signed-off-by: Kent Overstreet <koverstreet@google.com>
CC: Jens Axboe <axboe@kernel.dk>
Acked-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Muthukumar Ratty <muthur@gmail.com>
2012-09-10 14:33:46 -07:00
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2015-11-06 16:28:21 -08:00
|
|
|
|
|
|
|
|
|
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|
|
|
|
block: Avoid deadlocks with bio allocation by stacking drivers
Previously, if we ever try to allocate more than once from the same bio
set while running under generic_make_request() (i.e. a stacking block
driver), we risk deadlock.
This is because of the code in generic_make_request() that converts
recursion to iteration; any bios we submit won't actually be submitted
(so they can complete and eventually be freed) until after we return -
this means if we allocate a second bio, we're blocking the first one
from ever being freed.
Thus if enough threads call into a stacking block driver at the same
time with bios that need multiple splits, and the bio_set's reserve gets
used up, we deadlock.
This can be worked around in the driver code - we could check if we're
running under generic_make_request(), then mask out __GFP_WAIT when we
go to allocate a bio, and if the allocation fails punt to workqueue and
retry the allocation.
But this is tricky and not a generic solution. This patch solves it for
all users by inverting the previously described technique. We allocate a
rescuer workqueue for each bio_set, and then in the allocation code if
there are bios on current->bio_list we would be blocking, we punt them
to the rescuer workqueue to be submitted.
This guarantees forward progress for bio allocations under
generic_make_request() provided each bio is submitted before allocating
the next, and provided the bios are freed after they complete.
Note that this doesn't do anything for allocation from other mempools.
Instead of allocating per bio data structures from a mempool, code
should use bio_set's front_pad.
Tested it by forcing the rescue codepath to be taken (by disabling the
first GFP_NOWAIT) attempt, and then ran it with bcache (which does a lot
of arbitrary bio splitting) and verified that the rescuer was being
invoked.
Signed-off-by: Kent Overstreet <koverstreet@google.com>
CC: Jens Axboe <axboe@kernel.dk>
Acked-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Muthukumar Ratty <muthur@gmail.com>
2012-09-10 14:33:46 -07:00
|
|
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|
|
|
|
|
|
2017-03-10 17:00:47 +11:00
|
|
|
|
|
|
|
|
|
2017-06-18 14:38:57 +10:00
|
|
|
|
|
|
|
|
|
2015-11-06 16:28:21 -08:00
|
|
|
|
block: Avoid deadlocks with bio allocation by stacking drivers
Previously, if we ever try to allocate more than once from the same bio
set while running under generic_make_request() (i.e. a stacking block
driver), we risk deadlock.
This is because of the code in generic_make_request() that converts
recursion to iteration; any bios we submit won't actually be submitted
(so they can complete and eventually be freed) until after we return -
this means if we allocate a second bio, we're blocking the first one
from ever being freed.
Thus if enough threads call into a stacking block driver at the same
time with bios that need multiple splits, and the bio_set's reserve gets
used up, we deadlock.
This can be worked around in the driver code - we could check if we're
running under generic_make_request(), then mask out __GFP_WAIT when we
go to allocate a bio, and if the allocation fails punt to workqueue and
retry the allocation.
But this is tricky and not a generic solution. This patch solves it for
all users by inverting the previously described technique. We allocate a
rescuer workqueue for each bio_set, and then in the allocation code if
there are bios on current->bio_list we would be blocking, we punt them
to the rescuer workqueue to be submitted.
This guarantees forward progress for bio allocations under
generic_make_request() provided each bio is submitted before allocating
the next, and provided the bios are freed after they complete.
Note that this doesn't do anything for allocation from other mempools.
Instead of allocating per bio data structures from a mempool, code
should use bio_set's front_pad.
Tested it by forcing the rescue codepath to be taken (by disabling the
first GFP_NOWAIT) attempt, and then ran it with bcache (which does a lot
of arbitrary bio splitting) and verified that the rescuer was being
invoked.
Signed-off-by: Kent Overstreet <koverstreet@google.com>
CC: Jens Axboe <axboe@kernel.dk>
Acked-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Muthukumar Ratty <muthur@gmail.com>
2012-09-10 14:33:46 -07:00
|
|
|
|
2012-09-06 15:35:01 -07:00
|
|
|
|
block: Avoid deadlocks with bio allocation by stacking drivers
Previously, if we ever try to allocate more than once from the same bio
set while running under generic_make_request() (i.e. a stacking block
driver), we risk deadlock.
This is because of the code in generic_make_request() that converts
recursion to iteration; any bios we submit won't actually be submitted
(so they can complete and eventually be freed) until after we return -
this means if we allocate a second bio, we're blocking the first one
from ever being freed.
Thus if enough threads call into a stacking block driver at the same
time with bios that need multiple splits, and the bio_set's reserve gets
used up, we deadlock.
This can be worked around in the driver code - we could check if we're
running under generic_make_request(), then mask out __GFP_WAIT when we
go to allocate a bio, and if the allocation fails punt to workqueue and
retry the allocation.
But this is tricky and not a generic solution. This patch solves it for
all users by inverting the previously described technique. We allocate a
rescuer workqueue for each bio_set, and then in the allocation code if
there are bios on current->bio_list we would be blocking, we punt them
to the rescuer workqueue to be submitted.
This guarantees forward progress for bio allocations under
generic_make_request() provided each bio is submitted before allocating
the next, and provided the bios are freed after they complete.
Note that this doesn't do anything for allocation from other mempools.
Instead of allocating per bio data structures from a mempool, code
should use bio_set's front_pad.
Tested it by forcing the rescue codepath to be taken (by disabling the
first GFP_NOWAIT) attempt, and then ran it with bcache (which does a lot
of arbitrary bio splitting) and verified that the rescuer was being
invoked.
Signed-off-by: Kent Overstreet <koverstreet@google.com>
CC: Jens Axboe <axboe@kernel.dk>
Acked-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Muthukumar Ratty <muthur@gmail.com>
2012-09-10 14:33:46 -07:00
|
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2012-09-06 15:35:01 -07:00
|
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2009-04-15 19:50:51 +02:00
|
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2005-04-16 15:20:36 -07:00
|
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2012-09-06 15:35:01 -07:00
|
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|
2016-11-22 08:57:21 -07:00
|
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|
2009-02-21 11:16:36 +01:00
|
|
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|
2012-09-06 15:35:01 -07:00
|
|
|
|
2016-07-19 11:28:42 +02:00
|
|
|
|
|
|
|
|
|
2012-10-12 15:29:33 -07:00
|
|
|
|
block: Avoid deadlocks with bio allocation by stacking drivers
Previously, if we ever try to allocate more than once from the same bio
set while running under generic_make_request() (i.e. a stacking block
driver), we risk deadlock.
This is because of the code in generic_make_request() that converts
recursion to iteration; any bios we submit won't actually be submitted
(so they can complete and eventually be freed) until after we return -
this means if we allocate a second bio, we're blocking the first one
from ever being freed.
Thus if enough threads call into a stacking block driver at the same
time with bios that need multiple splits, and the bio_set's reserve gets
used up, we deadlock.
This can be worked around in the driver code - we could check if we're
running under generic_make_request(), then mask out __GFP_WAIT when we
go to allocate a bio, and if the allocation fails punt to workqueue and
retry the allocation.
But this is tricky and not a generic solution. This patch solves it for
all users by inverting the previously described technique. We allocate a
rescuer workqueue for each bio_set, and then in the allocation code if
there are bios on current->bio_list we would be blocking, we punt them
to the rescuer workqueue to be submitted.
This guarantees forward progress for bio allocations under
generic_make_request() provided each bio is submitted before allocating
the next, and provided the bios are freed after they complete.
Note that this doesn't do anything for allocation from other mempools.
Instead of allocating per bio data structures from a mempool, code
should use bio_set's front_pad.
Tested it by forcing the rescue codepath to be taken (by disabling the
first GFP_NOWAIT) attempt, and then ran it with bcache (which does a lot
of arbitrary bio splitting) and verified that the rescuer was being
invoked.
Signed-off-by: Kent Overstreet <koverstreet@google.com>
CC: Jens Axboe <axboe@kernel.dk>
Acked-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Muthukumar Ratty <muthur@gmail.com>
2012-09-10 14:33:46 -07:00
|
|
|
|
|
|
|
|
|
|
|
|
|
|
2012-10-12 15:29:33 -07:00
|
|
|
|
block: Avoid deadlocks with bio allocation by stacking drivers
Previously, if we ever try to allocate more than once from the same bio
set while running under generic_make_request() (i.e. a stacking block
driver), we risk deadlock.
This is because of the code in generic_make_request() that converts
recursion to iteration; any bios we submit won't actually be submitted
(so they can complete and eventually be freed) until after we return -
this means if we allocate a second bio, we're blocking the first one
from ever being freed.
Thus if enough threads call into a stacking block driver at the same
time with bios that need multiple splits, and the bio_set's reserve gets
used up, we deadlock.
This can be worked around in the driver code - we could check if we're
running under generic_make_request(), then mask out __GFP_WAIT when we
go to allocate a bio, and if the allocation fails punt to workqueue and
retry the allocation.
But this is tricky and not a generic solution. This patch solves it for
all users by inverting the previously described technique. We allocate a
rescuer workqueue for each bio_set, and then in the allocation code if
there are bios on current->bio_list we would be blocking, we punt them
to the rescuer workqueue to be submitted.
This guarantees forward progress for bio allocations under
generic_make_request() provided each bio is submitted before allocating
the next, and provided the bios are freed after they complete.
Note that this doesn't do anything for allocation from other mempools.
Instead of allocating per bio data structures from a mempool, code
should use bio_set's front_pad.
Tested it by forcing the rescue codepath to be taken (by disabling the
first GFP_NOWAIT) attempt, and then ran it with bcache (which does a lot
of arbitrary bio splitting) and verified that the rescuer was being
invoked.
Signed-off-by: Kent Overstreet <koverstreet@google.com>
CC: Jens Axboe <axboe@kernel.dk>
Acked-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Muthukumar Ratty <muthur@gmail.com>
2012-09-10 14:33:46 -07:00
|
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|
2009-02-21 11:16:36 +01:00
|
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|
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|
2012-05-25 13:03:11 -07:00
|
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|
|
2016-07-19 11:28:42 +02:00
|
|
|
|
2012-09-06 15:35:01 -07:00
|
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2005-04-16 15:20:36 -07:00
|
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2012-09-06 15:35:01 -07:00
|
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|
2009-02-21 11:16:36 +01:00
|
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2005-04-16 15:20:36 -07:00
|
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2009-02-21 11:16:36 +01:00
|
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|
2009-04-15 19:50:51 +02:00
|
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2009-02-21 11:16:36 +01:00
|
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|
2005-04-16 15:20:36 -07:00
|
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2009-09-26 16:19:21 +02:00
|
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2005-04-16 15:20:36 -07:00
|
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2013-11-23 17:19:00 -08:00
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2005-04-16 15:20:36 -07:00
|
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2013-11-23 17:19:00 -08:00
|
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2005-04-16 15:20:36 -07:00
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2017-06-18 14:38:59 +10:00
|
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|
2005-04-16 15:20:36 -07:00
|
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2015-04-17 16:23:59 -06:00
|
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|
2012-09-06 15:35:00 -07:00
|
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2015-04-17 16:23:59 -06:00
|
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2005-04-16 15:20:36 -07:00
|
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2009-09-26 16:19:21 +02:00
|
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|
2005-04-16 15:20:36 -07:00
|
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|
2007-07-24 09:28:11 +02:00
|
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2005-04-16 15:20:36 -07:00
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2009-09-26 16:19:21 +02:00
|
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2005-04-16 15:20:36 -07:00
|
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|
2013-11-23 18:19:27 -08:00
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|
|
2016-07-19 11:28:42 +02:00
|
|
|
|
2013-11-23 18:19:27 -08:00
|
|
|
|
|
|
|
|
|
2017-08-23 19:10:32 +02:00
|
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|
2013-11-23 18:19:27 -08:00
|
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|
2017-08-23 19:10:32 +02:00
|
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|
2017-11-16 23:47:25 -08:00
|
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|
2015-07-24 12:37:59 -06:00
|
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|
2017-12-20 11:10:17 -07:00
|
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|
2016-08-05 15:35:16 -06:00
|
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|
2017-06-27 09:22:02 -06:00
|
|
|
|
2013-11-23 18:19:27 -08:00
|
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|
2016-07-27 07:22:05 +02:00
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2013-11-23 18:19:27 -08:00
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2017-03-24 10:34:43 -07:00
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2005-04-16 15:20:36 -07:00
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2013-11-23 17:26:46 -08:00
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2005-04-16 15:20:36 -07:00
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2013-11-23 17:26:46 -08:00
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2017-03-24 10:34:43 -07:00
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2013-11-23 17:26:46 -08:00
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|
2008-06-30 20:04:41 +02:00
|
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2017-08-23 19:10:32 +02:00
|
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|
2016-08-05 15:35:16 -06:00
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2017-06-27 09:22:02 -06:00
|
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2013-11-23 17:26:46 -08:00
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2008-06-30 20:04:41 +02:00
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|
2016-08-16 10:59:35 +03:00
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2016-11-30 12:28:59 -08:00
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2016-08-16 10:59:35 +03:00
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2014-02-10 17:45:50 -08:00
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2016-08-16 10:59:35 +03:00
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2017-03-24 10:34:43 -07:00
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2016-08-16 10:59:35 +03:00
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2014-02-10 17:45:50 -08:00
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2013-11-23 17:26:46 -08:00
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2008-06-30 20:04:41 +02:00
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2013-11-23 17:26:46 -08:00
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2009-03-09 10:42:45 +01:00
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2013-11-23 17:26:46 -08:00
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2008-06-30 20:04:41 +02:00
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2009-03-09 10:42:45 +01:00
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2005-09-06 15:16:42 -07:00
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2005-04-16 15:20:36 -07:00
|
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2016-07-27 07:22:05 +02:00
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2013-11-23 17:26:46 -08:00
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2005-04-16 15:20:36 -07:00
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2012-09-06 15:35:02 -07:00
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2005-04-16 15:20:36 -07:00
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2013-11-23 22:30:22 -08:00
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2005-04-16 15:20:36 -07:00
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2013-11-23 22:30:22 -08:00
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2005-04-16 15:20:36 -07:00
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2013-11-23 22:30:22 -08:00
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2005-04-16 15:20:36 -07:00
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2013-11-23 22:30:22 -08:00
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2005-04-16 15:20:36 -07:00
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2006-01-06 09:43:28 +01:00
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2014-12-10 14:16:53 -08:00
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2006-01-06 09:43:28 +01:00
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2014-06-24 16:22:24 -06:00
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2015-08-19 14:24:05 -07:00
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2014-06-24 16:22:24 -06:00
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2006-01-06 09:43:28 +01:00
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2005-04-16 15:20:36 -07:00
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2014-12-10 14:16:53 -08:00
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2005-04-16 15:20:36 -07:00
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2014-12-10 14:16:53 -08:00
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2005-04-16 15:20:36 -07:00
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2014-12-10 14:16:53 -08:00
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2005-04-16 15:20:36 -07:00
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2014-12-10 14:16:53 -08:00
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2015-07-24 12:37:59 -06:00
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2005-04-16 15:20:36 -07:00
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2006-01-06 09:43:28 +01:00
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2005-04-16 15:20:36 -07:00
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2014-12-10 14:16:53 -08:00
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2005-04-16 15:20:36 -07:00
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2009-09-26 16:19:21 +02:00
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2005-11-11 05:30:27 -06:00
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2005-04-16 15:20:36 -07:00
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2013-11-23 22:30:22 -08:00
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2005-04-16 15:20:36 -07:00
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2013-11-23 22:30:22 -08:00
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2005-04-16 15:20:36 -07:00
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2013-11-23 22:30:22 -08:00
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2014-06-05 13:38:39 -06:00
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2013-11-23 22:30:22 -08:00
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2014-06-10 12:53:56 -06:00
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2013-11-23 22:30:22 -08:00
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2005-04-16 15:20:36 -07:00
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2009-09-26 16:19:21 +02:00
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2005-04-16 15:20:36 -07:00
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2016-10-31 11:59:24 -06:00
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2015-07-20 15:29:37 +02:00
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2012-09-10 14:41:12 -07:00
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2017-10-25 17:55:57 +09:00
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2012-09-10 14:41:12 -07:00
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2017-08-02 10:25:21 +02:00
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2012-09-10 14:41:12 -07:00
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2016-06-05 14:31:41 -05:00
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2012-09-10 14:41:12 -07:00
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2017-10-25 17:56:05 +09:00
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2012-09-10 14:41:12 -07:00
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2017-10-25 17:55:57 +09:00
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2012-09-10 14:41:12 -07:00
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2016-08-05 15:35:16 -06:00
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2016-06-05 14:31:41 -05:00
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2017-10-25 17:55:57 +09:00
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2012-09-10 14:41:12 -07:00
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2017-10-25 17:55:57 +09:00
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2012-09-10 14:41:12 -07:00
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2012-09-28 13:17:55 -07:00
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2013-08-07 14:26:21 -07:00
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2012-09-28 13:17:55 -07:00
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2012-09-10 13:57:51 -07:00
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2013-08-07 14:26:39 -07:00
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2012-09-10 13:57:51 -07:00
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2013-08-07 14:26:39 -07:00
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2012-09-10 13:57:51 -07:00
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2013-08-07 14:26:39 -07:00
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2012-09-10 13:57:51 -07:00
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2013-08-07 14:26:39 -07:00
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2012-09-10 13:57:51 -07:00
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2013-08-07 14:26:39 -07:00
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2012-09-10 13:57:51 -07:00
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2013-08-07 14:26:39 -07:00
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2012-09-10 13:57:51 -07:00
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2013-08-07 14:26:39 -07:00
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2012-09-10 13:57:51 -07:00
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2013-08-07 14:26:39 -07:00
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2012-09-10 13:57:51 -07:00
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2013-08-07 14:26:39 -07:00
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2012-09-10 13:57:51 -07:00
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2013-08-07 14:26:39 -07:00
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2012-09-10 13:57:51 -07:00
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2013-08-07 14:26:39 -07:00
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2012-09-10 13:57:51 -07:00
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2005-04-16 15:20:36 -07:00
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2008-08-28 16:17:06 +09:00
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2015-01-18 16:16:31 +01:00
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2005-04-16 15:20:36 -07:00
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2017-09-24 13:14:35 -04:00
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2008-08-25 20:36:08 +02:00
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2005-04-16 15:20:36 -07:00
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2017-09-24 13:14:35 -04:00
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2010-10-29 11:46:56 -06:00
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2005-04-16 15:20:36 -07:00
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2017-09-24 13:14:35 -04:00
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2005-04-16 15:20:36 -07:00
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2015-01-18 16:16:34 +01:00
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2017-09-24 12:14:36 -04:00
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2008-04-11 12:56:49 +02:00
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2015-01-18 16:16:34 +01:00
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2008-04-11 12:56:49 +02:00
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2013-02-06 12:23:11 -08:00
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2015-01-18 16:16:34 +01:00
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2008-04-11 12:56:49 +02:00
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2015-01-18 16:16:34 +01:00
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2017-09-24 12:14:36 -04:00
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2015-01-18 16:16:34 +01:00
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2017-09-24 12:14:36 -04:00
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2015-01-18 16:16:34 +01:00
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2008-04-11 12:56:49 +02:00
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2015-01-18 16:16:34 +01:00
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2008-04-11 12:56:49 +02:00
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2016-09-22 03:10:01 -04:00
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2015-01-18 16:16:30 +01:00
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2016-09-22 03:10:01 -04:00
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2015-01-18 16:16:30 +01:00
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2005-04-16 15:20:36 -07:00
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2015-01-18 16:16:29 +01:00
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2005-04-16 15:20:36 -07:00
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2015-01-18 16:16:30 +01:00
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2005-04-16 15:20:36 -07:00
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|
[SCSI] sg: Fix user memory corruption when SG_IO is interrupted by a signal
There is a nasty bug in the SCSI SG_IO ioctl that in some circumstances
leads to one process writing data into the address space of some other
random unrelated process if the ioctl is interrupted by a signal.
What happens is the following:
- A process issues an SG_IO ioctl with direction DXFER_FROM_DEV (ie the
underlying SCSI command will transfer data from the SCSI device to
the buffer provided in the ioctl)
- Before the command finishes, a signal is sent to the process waiting
in the ioctl. This will end up waking up the sg_ioctl() code:
result = wait_event_interruptible(sfp->read_wait,
(srp_done(sfp, srp) || sdp->detached));
but neither srp_done() nor sdp->detached is true, so we end up just
setting srp->orphan and returning to userspace:
srp->orphan = 1;
write_unlock_irq(&sfp->rq_list_lock);
return result; /* -ERESTARTSYS because signal hit process */
At this point the original process is done with the ioctl and
blithely goes ahead handling the signal, reissuing the ioctl, etc.
- Eventually, the SCSI command issued by the first ioctl finishes and
ends up in sg_rq_end_io(). At the end of that function, we run through:
write_lock_irqsave(&sfp->rq_list_lock, iflags);
if (unlikely(srp->orphan)) {
if (sfp->keep_orphan)
srp->sg_io_owned = 0;
else
done = 0;
}
srp->done = done;
write_unlock_irqrestore(&sfp->rq_list_lock, iflags);
if (likely(done)) {
/* Now wake up any sg_read() that is waiting for this
* packet.
*/
wake_up_interruptible(&sfp->read_wait);
kill_fasync(&sfp->async_qp, SIGPOLL, POLL_IN);
kref_put(&sfp->f_ref, sg_remove_sfp);
} else {
INIT_WORK(&srp->ew.work, sg_rq_end_io_usercontext);
schedule_work(&srp->ew.work);
}
Since srp->orphan *is* set, we set done to 0 (assuming the
userspace app has not set keep_orphan via an SG_SET_KEEP_ORPHAN
ioctl), and therefore we end up scheduling sg_rq_end_io_usercontext()
to run in a workqueue.
- In workqueue context we go through sg_rq_end_io_usercontext() ->
sg_finish_rem_req() -> blk_rq_unmap_user() -> ... ->
bio_uncopy_user() -> __bio_copy_iov() -> copy_to_user().
The key point here is that we are doing copy_to_user() on a
workqueue -- that is, we're on a kernel thread with current->mm
equal to whatever random previous user process was scheduled before
this kernel thread. So we end up copying whatever data the SCSI
command returned to the virtual address of the buffer passed into
the original ioctl, but it's quite likely we do this copying into a
different address space!
As suggested by James Bottomley <James.Bottomley@hansenpartnership.com>,
add a check for current->mm (which is NULL if we're on a kernel thread
without a real userspace address space) in bio_uncopy_user(), and skip
the copy if we're on a kernel thread.
There's no reason that I can think of for any caller of bio_uncopy_user()
to want to do copying on a kernel thread with a random active userspace
address space.
Huge thanks to Costa Sapuntzakis <costa@purestorage.com> for the
original pointer to this bug in the sg code.
Signed-off-by: Roland Dreier <roland@purestorage.com>
Tested-by: David Milburn <dmilburn@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: <stable@vger.kernel.org>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>
2013-08-05 17:55:01 -07:00
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2016-02-12 09:39:15 +01:00
|
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|
[SCSI] sg: Fix user memory corruption when SG_IO is interrupted by a signal
There is a nasty bug in the SCSI SG_IO ioctl that in some circumstances
leads to one process writing data into the address space of some other
random unrelated process if the ioctl is interrupted by a signal.
What happens is the following:
- A process issues an SG_IO ioctl with direction DXFER_FROM_DEV (ie the
underlying SCSI command will transfer data from the SCSI device to
the buffer provided in the ioctl)
- Before the command finishes, a signal is sent to the process waiting
in the ioctl. This will end up waking up the sg_ioctl() code:
result = wait_event_interruptible(sfp->read_wait,
(srp_done(sfp, srp) || sdp->detached));
but neither srp_done() nor sdp->detached is true, so we end up just
setting srp->orphan and returning to userspace:
srp->orphan = 1;
write_unlock_irq(&sfp->rq_list_lock);
return result; /* -ERESTARTSYS because signal hit process */
At this point the original process is done with the ioctl and
blithely goes ahead handling the signal, reissuing the ioctl, etc.
- Eventually, the SCSI command issued by the first ioctl finishes and
ends up in sg_rq_end_io(). At the end of that function, we run through:
write_lock_irqsave(&sfp->rq_list_lock, iflags);
if (unlikely(srp->orphan)) {
if (sfp->keep_orphan)
srp->sg_io_owned = 0;
else
done = 0;
}
srp->done = done;
write_unlock_irqrestore(&sfp->rq_list_lock, iflags);
if (likely(done)) {
/* Now wake up any sg_read() that is waiting for this
* packet.
*/
wake_up_interruptible(&sfp->read_wait);
kill_fasync(&sfp->async_qp, SIGPOLL, POLL_IN);
kref_put(&sfp->f_ref, sg_remove_sfp);
} else {
INIT_WORK(&srp->ew.work, sg_rq_end_io_usercontext);
schedule_work(&srp->ew.work);
}
Since srp->orphan *is* set, we set done to 0 (assuming the
userspace app has not set keep_orphan via an SG_SET_KEEP_ORPHAN
ioctl), and therefore we end up scheduling sg_rq_end_io_usercontext()
to run in a workqueue.
- In workqueue context we go through sg_rq_end_io_usercontext() ->
sg_finish_rem_req() -> blk_rq_unmap_user() -> ... ->
bio_uncopy_user() -> __bio_copy_iov() -> copy_to_user().
The key point here is that we are doing copy_to_user() on a
workqueue -- that is, we're on a kernel thread with current->mm
equal to whatever random previous user process was scheduled before
this kernel thread. So we end up copying whatever data the SCSI
command returned to the virtual address of the buffer passed into
the original ioctl, but it's quite likely we do this copying into a
different address space!
As suggested by James Bottomley <James.Bottomley@hansenpartnership.com>,
add a check for current->mm (which is NULL if we're on a kernel thread
without a real userspace address space) in bio_uncopy_user(), and skip
the copy if we're on a kernel thread.
There's no reason that I can think of for any caller of bio_uncopy_user()
to want to do copying on a kernel thread with a random active userspace
address space.
Huge thanks to Costa Sapuntzakis <costa@purestorage.com> for the
original pointer to this bug in the sg code.
Signed-off-by: Roland Dreier <roland@purestorage.com>
Tested-by: David Milburn <dmilburn@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: <stable@vger.kernel.org>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>
2013-08-05 17:55:01 -07:00
|
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2016-02-12 09:39:15 +01:00
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2015-01-18 16:16:34 +01:00
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2015-01-18 16:16:30 +01:00
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[SCSI] sg: Fix user memory corruption when SG_IO is interrupted by a signal
There is a nasty bug in the SCSI SG_IO ioctl that in some circumstances
leads to one process writing data into the address space of some other
random unrelated process if the ioctl is interrupted by a signal.
What happens is the following:
- A process issues an SG_IO ioctl with direction DXFER_FROM_DEV (ie the
underlying SCSI command will transfer data from the SCSI device to
the buffer provided in the ioctl)
- Before the command finishes, a signal is sent to the process waiting
in the ioctl. This will end up waking up the sg_ioctl() code:
result = wait_event_interruptible(sfp->read_wait,
(srp_done(sfp, srp) || sdp->detached));
but neither srp_done() nor sdp->detached is true, so we end up just
setting srp->orphan and returning to userspace:
srp->orphan = 1;
write_unlock_irq(&sfp->rq_list_lock);
return result; /* -ERESTARTSYS because signal hit process */
At this point the original process is done with the ioctl and
blithely goes ahead handling the signal, reissuing the ioctl, etc.
- Eventually, the SCSI command issued by the first ioctl finishes and
ends up in sg_rq_end_io(). At the end of that function, we run through:
write_lock_irqsave(&sfp->rq_list_lock, iflags);
if (unlikely(srp->orphan)) {
if (sfp->keep_orphan)
srp->sg_io_owned = 0;
else
done = 0;
}
srp->done = done;
write_unlock_irqrestore(&sfp->rq_list_lock, iflags);
if (likely(done)) {
/* Now wake up any sg_read() that is waiting for this
* packet.
*/
wake_up_interruptible(&sfp->read_wait);
kill_fasync(&sfp->async_qp, SIGPOLL, POLL_IN);
kref_put(&sfp->f_ref, sg_remove_sfp);
} else {
INIT_WORK(&srp->ew.work, sg_rq_end_io_usercontext);
schedule_work(&srp->ew.work);
}
Since srp->orphan *is* set, we set done to 0 (assuming the
userspace app has not set keep_orphan via an SG_SET_KEEP_ORPHAN
ioctl), and therefore we end up scheduling sg_rq_end_io_usercontext()
to run in a workqueue.
- In workqueue context we go through sg_rq_end_io_usercontext() ->
sg_finish_rem_req() -> blk_rq_unmap_user() -> ... ->
bio_uncopy_user() -> __bio_copy_iov() -> copy_to_user().
The key point here is that we are doing copy_to_user() on a
workqueue -- that is, we're on a kernel thread with current->mm
equal to whatever random previous user process was scheduled before
this kernel thread. So we end up copying whatever data the SCSI
command returned to the virtual address of the buffer passed into
the original ioctl, but it's quite likely we do this copying into a
different address space!
As suggested by James Bottomley <James.Bottomley@hansenpartnership.com>,
add a check for current->mm (which is NULL if we're on a kernel thread
without a real userspace address space) in bio_uncopy_user(), and skip
the copy if we're on a kernel thread.
There's no reason that I can think of for any caller of bio_uncopy_user()
to want to do copying on a kernel thread with a random active userspace
address space.
Huge thanks to Costa Sapuntzakis <costa@purestorage.com> for the
original pointer to this bug in the sg code.
Signed-off-by: Roland Dreier <roland@purestorage.com>
Tested-by: David Milburn <dmilburn@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: <stable@vger.kernel.org>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>
2013-08-05 17:55:01 -07:00
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2013-11-22 19:39:06 -08:00
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2005-04-16 15:20:36 -07:00
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2008-04-11 12:56:49 +02:00
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2015-01-18 16:16:31 +01:00
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2005-04-16 15:20:36 -07:00
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2008-08-28 16:17:06 +09:00
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2017-09-24 09:25:39 -04:00
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2015-01-18 16:16:31 +01:00
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2005-04-16 15:20:36 -07:00
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2017-09-24 13:09:18 -04:00
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2015-01-18 16:16:31 +01:00
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2015-11-21 17:27:31 +08:00
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2005-04-16 15:20:36 -07:00
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2017-09-24 13:14:35 -04:00
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2005-04-16 15:20:36 -07:00
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2015-01-18 16:16:31 +01:00
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2017-09-24 13:09:18 -04:00
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2015-01-18 16:16:31 +01:00
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2005-04-16 15:20:36 -07:00
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2009-04-15 22:10:27 +09:00
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2005-04-16 15:20:36 -07:00
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2008-12-18 14:49:37 +09:00
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2008-12-18 14:49:36 +09:00
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2008-12-18 14:49:37 +09:00
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2005-04-16 15:20:36 -07:00
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2008-12-18 14:49:36 +09:00
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2005-04-16 15:20:36 -07:00
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2008-12-18 14:49:37 +09:00
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2005-04-16 15:20:36 -07:00
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2008-08-28 16:17:06 +09:00
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2008-12-18 14:49:36 +09:00
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2008-08-28 16:17:06 +09:00
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2008-12-18 14:49:36 +09:00
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2008-08-28 16:17:06 +09:00
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2008-12-18 14:49:36 +09:00
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2005-04-16 15:20:36 -07:00
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2008-12-18 14:49:37 +09:00
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2005-04-16 15:20:36 -07:00
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2008-12-18 14:49:37 +09:00
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2005-04-16 15:20:36 -07:00
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2017-09-24 12:09:21 -04:00
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2005-04-16 15:20:36 -07:00
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2015-01-18 16:16:31 +01:00
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2009-07-09 14:46:53 +02:00
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2017-09-24 12:14:36 -04:00
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2008-04-11 12:56:49 +02:00
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2017-09-24 12:14:36 -04:00
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2005-04-16 15:20:36 -07:00
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2015-01-18 16:16:31 +01:00
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2017-09-24 12:09:21 -04:00
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2005-04-16 15:20:36 -07:00
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2008-08-28 16:17:06 +09:00
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2015-01-18 16:16:30 +01:00
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2005-04-16 15:20:36 -07:00
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2013-11-22 19:39:06 -08:00
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2005-04-16 15:20:36 -07:00
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2015-01-18 16:16:33 +01:00
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2017-09-24 09:25:39 -04:00
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2015-01-18 16:16:33 +01:00
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2005-04-16 15:20:36 -07:00
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2015-01-18 16:16:31 +01:00
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2005-04-16 15:20:36 -07:00
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2017-09-23 16:08:57 -04:00
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2017-09-23 15:51:23 -04:00
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2005-04-16 15:20:36 -07:00
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2017-09-23 16:24:59 -04:00
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2005-04-16 15:20:36 -07:00
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2017-09-23 16:24:59 -04:00
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2005-04-16 15:20:36 -07:00
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2017-09-24 12:30:17 -04:00
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2017-09-23 16:13:10 -04:00
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2017-09-23 16:08:57 -04:00
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2005-04-16 15:20:36 -07:00
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2017-09-24 12:30:17 -04:00
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2017-09-23 16:08:57 -04:00
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2005-06-20 14:06:52 +02:00
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2006-06-16 13:02:29 +02:00
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2005-06-20 14:06:52 +02:00
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2017-09-23 16:08:57 -04:00
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2005-06-20 14:06:52 +02:00
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2017-09-23 16:23:18 -04:00
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2005-06-20 14:06:52 +02:00
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2017-09-23 16:23:18 -04:00
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2017-09-22 01:18:39 -04:00
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2017-09-23 16:23:18 -04:00
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2005-04-16 15:20:36 -07:00
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2017-09-23 16:23:18 -04:00
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2017-09-24 12:30:17 -04:00
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2005-06-20 14:06:52 +02:00
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2005-04-16 15:20:36 -07:00
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2005-06-20 14:06:52 +02:00
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2005-04-16 15:20:36 -07:00
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2017-09-23 16:13:10 -04:00
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|
mm, fs: get rid of PAGE_CACHE_* and page_cache_{get,release} macros
PAGE_CACHE_{SIZE,SHIFT,MASK,ALIGN} macros were introduced *long* time
ago with promise that one day it will be possible to implement page
cache with bigger chunks than PAGE_SIZE.
This promise never materialized. And unlikely will.
We have many places where PAGE_CACHE_SIZE assumed to be equal to
PAGE_SIZE. And it's constant source of confusion on whether
PAGE_CACHE_* or PAGE_* constant should be used in a particular case,
especially on the border between fs and mm.
Global switching to PAGE_CACHE_SIZE != PAGE_SIZE would cause to much
breakage to be doable.
Let's stop pretending that pages in page cache are special. They are
not.
The changes are pretty straight-forward:
- <foo> << (PAGE_CACHE_SHIFT - PAGE_SHIFT) -> <foo>;
- <foo> >> (PAGE_CACHE_SHIFT - PAGE_SHIFT) -> <foo>;
- PAGE_CACHE_{SIZE,SHIFT,MASK,ALIGN} -> PAGE_{SIZE,SHIFT,MASK,ALIGN};
- page_cache_get() -> get_page();
- page_cache_release() -> put_page();
This patch contains automated changes generated with coccinelle using
script below. For some reason, coccinelle doesn't patch header files.
I've called spatch for them manually.
The only adjustment after coccinelle is revert of changes to
PAGE_CAHCE_ALIGN definition: we are going to drop it later.
There are few places in the code where coccinelle didn't reach. I'll
fix them manually in a separate patch. Comments and documentation also
will be addressed with the separate patch.
virtual patch
@@
expression E;
@@
- E << (PAGE_CACHE_SHIFT - PAGE_SHIFT)
+ E
@@
expression E;
@@
- E >> (PAGE_CACHE_SHIFT - PAGE_SHIFT)
+ E
@@
@@
- PAGE_CACHE_SHIFT
+ PAGE_SHIFT
@@
@@
- PAGE_CACHE_SIZE
+ PAGE_SIZE
@@
@@
- PAGE_CACHE_MASK
+ PAGE_MASK
@@
expression E;
@@
- PAGE_CACHE_ALIGN(E)
+ PAGE_ALIGN(E)
@@
expression E;
@@
- page_cache_get(E)
+ get_page(E)
@@
expression E;
@@
- page_cache_release(E)
+ put_page(E)
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-04-01 15:29:47 +03:00
|
|
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|
2017-09-23 16:13:10 -04:00
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2017-09-23 16:16:06 -04:00
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2005-04-16 15:20:36 -07:00
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2015-07-24 12:37:59 -06:00
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2015-01-18 16:16:33 +01:00
|
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|
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|
2017-02-01 08:20:08 -08:00
|
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|
2015-01-18 16:16:33 +01:00
|
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2005-04-16 15:20:36 -07:00
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2005-06-20 14:06:52 +02:00
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2017-09-23 15:51:23 -04:00
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2005-06-20 14:06:52 +02:00
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2005-04-16 15:20:36 -07:00
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2013-02-06 12:23:11 -08:00
|
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|
2005-04-16 15:20:36 -07:00
|
|
|
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|
|
|
|
|
|
mm, fs: get rid of PAGE_CACHE_* and page_cache_{get,release} macros
PAGE_CACHE_{SIZE,SHIFT,MASK,ALIGN} macros were introduced *long* time
ago with promise that one day it will be possible to implement page
cache with bigger chunks than PAGE_SIZE.
This promise never materialized. And unlikely will.
We have many places where PAGE_CACHE_SIZE assumed to be equal to
PAGE_SIZE. And it's constant source of confusion on whether
PAGE_CACHE_* or PAGE_* constant should be used in a particular case,
especially on the border between fs and mm.
Global switching to PAGE_CACHE_SIZE != PAGE_SIZE would cause to much
breakage to be doable.
Let's stop pretending that pages in page cache are special. They are
not.
The changes are pretty straight-forward:
- <foo> << (PAGE_CACHE_SHIFT - PAGE_SHIFT) -> <foo>;
- <foo> >> (PAGE_CACHE_SHIFT - PAGE_SHIFT) -> <foo>;
- PAGE_CACHE_{SIZE,SHIFT,MASK,ALIGN} -> PAGE_{SIZE,SHIFT,MASK,ALIGN};
- page_cache_get() -> get_page();
- page_cache_release() -> put_page();
This patch contains automated changes generated with coccinelle using
script below. For some reason, coccinelle doesn't patch header files.
I've called spatch for them manually.
The only adjustment after coccinelle is revert of changes to
PAGE_CAHCE_ALIGN definition: we are going to drop it later.
There are few places in the code where coccinelle didn't reach. I'll
fix them manually in a separate patch. Comments and documentation also
will be addressed with the separate patch.
virtual patch
@@
expression E;
@@
- E << (PAGE_CACHE_SHIFT - PAGE_SHIFT)
+ E
@@
expression E;
@@
- E >> (PAGE_CACHE_SHIFT - PAGE_SHIFT)
+ E
@@
@@
- PAGE_CACHE_SHIFT
+ PAGE_SHIFT
@@
@@
- PAGE_CACHE_SIZE
+ PAGE_SIZE
@@
@@
- PAGE_CACHE_MASK
+ PAGE_MASK
@@
expression E;
@@
- PAGE_CACHE_ALIGN(E)
+ PAGE_ALIGN(E)
@@
expression E;
@@
- page_cache_get(E)
+ get_page(E)
@@
expression E;
@@
- page_cache_release(E)
+ put_page(E)
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-04-01 15:29:47 +03:00
|
|
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2005-04-16 15:20:36 -07:00
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2017-02-01 08:20:08 -08:00
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2005-04-16 15:20:36 -07:00
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2015-07-20 15:29:37 +02:00
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2005-06-20 14:05:27 +02:00
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2015-01-18 16:16:32 +01:00
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2005-06-20 14:04:44 +02:00
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2009-04-15 22:10:27 +09:00
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2005-06-20 14:04:44 +02:00
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2005-12-05 02:37:06 -06:00
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2015-01-18 16:16:32 +01:00
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2005-06-20 14:04:44 +02:00
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2005-06-20 14:05:27 +02:00
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2005-06-20 14:04:44 +02:00
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2009-09-26 16:19:21 +02:00
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2005-06-20 14:04:44 +02:00
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2015-07-20 15:29:37 +02:00
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2008-04-25 12:47:50 +02:00
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2015-01-18 16:16:30 +01:00
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2015-07-20 15:29:37 +02:00
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2015-01-18 16:16:30 +01:00
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2015-01-18 16:16:28 +01:00
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2015-01-18 16:16:30 +01:00
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2008-04-25 12:47:50 +02:00
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2013-02-06 12:23:11 -08:00
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2015-01-18 16:16:30 +01:00
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2013-11-22 19:39:06 -08:00
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2008-04-25 12:47:50 +02:00
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2015-07-20 15:29:37 +02:00
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2008-04-25 12:47:50 +02:00
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2008-04-30 09:08:54 +02:00
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2008-04-25 12:47:50 +02:00
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2015-01-18 16:16:28 +01:00
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2015-01-18 16:16:30 +01:00
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2008-04-25 12:47:50 +02:00
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2015-01-18 16:16:28 +01:00
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2008-04-25 12:47:50 +02:00
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2015-01-18 16:16:28 +01:00
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2008-04-25 12:47:50 +02:00
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2015-01-18 16:16:28 +01:00
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2008-04-25 12:47:50 +02:00
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2015-01-18 16:16:28 +01:00
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2008-04-25 12:47:50 +02:00
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2015-01-18 16:16:30 +01:00
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2008-08-25 20:36:08 +02:00
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2008-04-25 12:47:50 +02:00
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2015-01-18 16:16:28 +01:00
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2015-01-18 16:16:30 +01:00
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2015-01-18 16:16:28 +01:00
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2008-04-25 12:47:50 +02:00
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2005-04-16 15:20:36 -07:00
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2012-07-25 18:12:08 +03:00
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2005-04-16 15:20:36 -07:00
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2012-09-05 15:22:02 -07:00
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2005-04-16 15:20:36 -07:00
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2012-09-05 15:22:02 -07:00
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2005-04-16 15:20:36 -07:00
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2008-02-18 13:48:32 +01:00
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2005-04-16 15:20:36 -07:00
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2012-09-05 15:22:02 -07:00
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2005-04-16 15:20:36 -07:00
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2012-09-05 15:22:02 -07:00
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2005-04-16 15:20:36 -07:00
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2016-04-01 15:29:48 +03:00
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2005-04-16 15:20:36 -07:00
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2006-11-22 14:55:48 +00:00
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2005-04-16 15:20:36 -07:00
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2006-11-22 14:55:48 +00:00
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2005-04-16 15:20:36 -07:00
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2006-11-22 14:55:48 +00:00
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2005-04-16 15:20:36 -07:00
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2012-09-05 15:22:02 -07:00
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2005-04-16 15:20:36 -07:00
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2012-09-05 15:22:02 -07:00
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2005-04-16 15:20:36 -07:00
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mm, fs: get rid of PAGE_CACHE_* and page_cache_{get,release} macros
PAGE_CACHE_{SIZE,SHIFT,MASK,ALIGN} macros were introduced *long* time
ago with promise that one day it will be possible to implement page
cache with bigger chunks than PAGE_SIZE.
This promise never materialized. And unlikely will.
We have many places where PAGE_CACHE_SIZE assumed to be equal to
PAGE_SIZE. And it's constant source of confusion on whether
PAGE_CACHE_* or PAGE_* constant should be used in a particular case,
especially on the border between fs and mm.
Global switching to PAGE_CACHE_SIZE != PAGE_SIZE would cause to much
breakage to be doable.
Let's stop pretending that pages in page cache are special. They are
not.
The changes are pretty straight-forward:
- <foo> << (PAGE_CACHE_SHIFT - PAGE_SHIFT) -> <foo>;
- <foo> >> (PAGE_CACHE_SHIFT - PAGE_SHIFT) -> <foo>;
- PAGE_CACHE_{SIZE,SHIFT,MASK,ALIGN} -> PAGE_{SIZE,SHIFT,MASK,ALIGN};
- page_cache_get() -> get_page();
- page_cache_release() -> put_page();
This patch contains automated changes generated with coccinelle using
script below. For some reason, coccinelle doesn't patch header files.
I've called spatch for them manually.
The only adjustment after coccinelle is revert of changes to
PAGE_CAHCE_ALIGN definition: we are going to drop it later.
There are few places in the code where coccinelle didn't reach. I'll
fix them manually in a separate patch. Comments and documentation also
will be addressed with the separate patch.
virtual patch
@@
expression E;
@@
- E << (PAGE_CACHE_SHIFT - PAGE_SHIFT)
+ E
@@
expression E;
@@
- E >> (PAGE_CACHE_SHIFT - PAGE_SHIFT)
+ E
@@
@@
- PAGE_CACHE_SHIFT
+ PAGE_SHIFT
@@
@@
- PAGE_CACHE_SIZE
+ PAGE_SIZE
@@
@@
- PAGE_CACHE_MASK
+ PAGE_MASK
@@
expression E;
@@
- PAGE_CACHE_ALIGN(E)
+ PAGE_ALIGN(E)
@@
expression E;
@@
- page_cache_get(E)
+ get_page(E)
@@
expression E;
@@
- page_cache_release(E)
+ put_page(E)
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-04-01 15:29:47 +03:00
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2012-09-05 15:22:02 -07:00
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2005-04-16 15:20:36 -07:00
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2017-06-30 21:55:08 -06:00
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2014-11-24 11:05:22 +08:00
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2017-06-30 21:55:08 -06:00
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2014-11-24 11:05:22 +08:00
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2017-06-30 21:55:08 -06:00
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2014-11-24 11:05:22 +08:00
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2017-06-30 21:55:08 -06:00
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2014-11-24 11:05:22 +08:00
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2017-06-30 21:55:08 -06:00
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2014-11-24 11:05:22 +08:00
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2009-11-26 09:16:19 +01:00
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2013-11-23 17:19:00 -08:00
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2009-11-26 09:16:19 +01:00
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2013-11-23 17:19:00 -08:00
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2009-11-26 09:16:19 +01:00
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2015-04-17 16:15:18 -06:00
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2015-05-22 09:14:03 -04:00
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2015-07-24 12:37:59 -06:00
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2015-04-17 16:15:18 -06:00
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2015-05-22 09:14:03 -04:00
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2015-04-17 16:15:18 -06:00
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2005-04-16 15:20:36 -07:00
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2015-07-20 15:29:37 +02:00
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block: trace completion of all bios.
Currently only dm and md/raid5 bios trigger
trace_block_bio_complete(). Now that we have bio_chain() and
bio_inc_remaining(), it is not possible, in general, for a driver to
know when the bio is really complete. Only bio_endio() knows that.
So move the trace_block_bio_complete() call to bio_endio().
Now trace_block_bio_complete() pairs with trace_block_bio_queue().
Any bio for which a 'queue' event is traced, will subsequently
generate a 'complete' event.
There are a few cases where completion tracing is not wanted.
1/ If blk_update_request() has already generated a completion
trace event at the 'request' level, there is no point generating
one at the bio level too. In this case the bi_sector and bi_size
will have changed, so the bio level event would be wrong
2/ If the bio hasn't actually been queued yet, but is being aborted
early, then a trace event could be confusing. Some filesystems
call bio_endio() but do not want tracing.
3/ The bio_integrity code interposes itself by replacing bi_end_io,
then restoring it and calling bio_endio() again. This would produce
two identical trace events if left like that.
To handle these, we introduce a flag BIO_TRACE_COMPLETION and only
produce the trace event when this is set.
We address point 1 above by clearing the flag in blk_update_request().
We address point 2 above by only setting the flag when
generic_make_request() is called.
We address point 3 above by clearing the flag after generating a
completion event.
When bio_split() is used on a bio, particularly in blk_queue_split(),
there is an extra complication. A new bio is split off the front, and
may be handle directly without going through generic_make_request().
The old bio, which has been advanced, is passed to
generic_make_request(), so it will trigger a trace event a second
time.
Probably the best result when a split happens is to see a single
'queue' event for the whole bio, then multiple 'complete' events - one
for each component. To achieve this was can:
- copy the BIO_TRACE_COMPLETION flag to the new bio in bio_split()
- avoid generating a 'queue' event if BIO_TRACE_COMPLETION is already set.
This way, the split-off bio won't create a queue event, the original
won't either even if it re-submitted to generic_make_request(),
but both will produce completion events, each for their own range.
So if generic_make_request() is called (which generates a QUEUED
event), then bi_endio() will create a single COMPLETE event for each
range that the bio is split into, unless the driver has explicitly
requested it not to.
Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2017-04-07 09:40:52 -06:00
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2005-04-16 15:20:36 -07:00
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2015-07-20 15:29:37 +02:00
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2005-04-16 15:20:36 -07:00
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2016-03-11 17:34:52 +01:00
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2016-03-11 17:34:53 +01:00
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2016-03-11 17:34:52 +01:00
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2017-07-03 16:58:43 -06:00
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2005-04-16 15:20:36 -07:00
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2016-03-11 17:34:52 +01:00
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2013-11-23 18:34:15 -08:00
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2016-03-11 17:34:52 +01:00
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2017-08-23 19:10:32 +02:00
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2017-06-13 08:07:33 -07:00
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block: trace completion of all bios.
Currently only dm and md/raid5 bios trigger
trace_block_bio_complete(). Now that we have bio_chain() and
bio_inc_remaining(), it is not possible, in general, for a driver to
know when the bio is really complete. Only bio_endio() knows that.
So move the trace_block_bio_complete() call to bio_endio().
Now trace_block_bio_complete() pairs with trace_block_bio_queue().
Any bio for which a 'queue' event is traced, will subsequently
generate a 'complete' event.
There are a few cases where completion tracing is not wanted.
1/ If blk_update_request() has already generated a completion
trace event at the 'request' level, there is no point generating
one at the bio level too. In this case the bi_sector and bi_size
will have changed, so the bio level event would be wrong
2/ If the bio hasn't actually been queued yet, but is being aborted
early, then a trace event could be confusing. Some filesystems
call bio_endio() but do not want tracing.
3/ The bio_integrity code interposes itself by replacing bi_end_io,
then restoring it and calling bio_endio() again. This would produce
two identical trace events if left like that.
To handle these, we introduce a flag BIO_TRACE_COMPLETION and only
produce the trace event when this is set.
We address point 1 above by clearing the flag in blk_update_request().
We address point 2 above by only setting the flag when
generic_make_request() is called.
We address point 3 above by clearing the flag after generating a
completion event.
When bio_split() is used on a bio, particularly in blk_queue_split(),
there is an extra complication. A new bio is split off the front, and
may be handle directly without going through generic_make_request().
The old bio, which has been advanced, is passed to
generic_make_request(), so it will trigger a trace event a second
time.
Probably the best result when a split happens is to see a single
'queue' event for the whole bio, then multiple 'complete' events - one
for each component. To achieve this was can:
- copy the BIO_TRACE_COMPLETION flag to the new bio in bio_split()
- avoid generating a 'queue' event if BIO_TRACE_COMPLETION is already set.
This way, the split-off bio won't create a queue event, the original
won't either even if it re-submitted to generic_make_request(),
but both will produce completion events, each for their own range.
So if generic_make_request() is called (which generates a QUEUED
event), then bi_endio() will create a single COMPLETE event for each
range that the bio is split into, unless the driver has explicitly
requested it not to.
Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2017-04-07 09:40:52 -06:00
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blk-throttle: add a simple idle detection
A cgroup gets assigned a low limit, but the cgroup could never dispatch
enough IO to cross the low limit. In such case, the queue state machine
will remain in LIMIT_LOW state and all other cgroups will be throttled
according to low limit. This is unfair for other cgroups. We should
treat the cgroup idle and upgrade the state machine to lower state.
We also have a downgrade logic. If the state machine upgrades because of
cgroup idle (real idle), the state machine will downgrade soon as the
cgroup is below its low limit. This isn't what we want. A more
complicated case is cgroup isn't idle when queue is in LIMIT_LOW. But
when queue gets upgraded to lower state, other cgroups could dispatch
more IO and this cgroup can't dispatch enough IO, so the cgroup is below
its low limit and looks like idle (fake idle). In this case, the queue
should downgrade soon. The key to determine if we should do downgrade is
to detect if cgroup is truely idle.
Unfortunately it's very hard to determine if a cgroup is real idle. This
patch uses the 'think time check' idea from CFQ for the purpose. Please
note, the idea doesn't work for all workloads. For example, a workload
with io depth 8 has disk utilization 100%, hence think time is 0, eg,
not idle. But the workload can run higher bandwidth with io depth 16.
Compared to io depth 16, the io depth 8 workload is idle. We use the
idea to roughly determine if a cgroup is idle.
We treat a cgroup idle if its think time is above a threshold (by
default 1ms for SSD and 100ms for HD). The idea is think time above the
threshold will start to harm performance. HD is much slower so a longer
think time is ok.
The patch (and the latter patches) uses 'unsigned long' to track time.
We convert 'ns' to 'us' with 'ns >> 10'. This is fast but loses
precision, should not a big deal.
Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2017-03-27 10:51:41 -07:00
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2017-07-10 11:40:17 -07:00
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2016-03-11 17:34:52 +01:00
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2005-04-16 15:20:36 -07:00
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2009-09-26 16:19:21 +02:00
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2005-04-16 15:20:36 -07:00
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2013-11-23 18:21:01 -08:00
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2015-07-22 07:57:12 -04:00
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2013-11-23 18:21:01 -08:00
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2017-11-22 13:18:05 -05:00
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2013-11-23 18:21:01 -08:00
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2016-12-08 15:20:32 -07:00
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2013-11-23 18:21:01 -08:00
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2017-06-29 11:31:10 -07:00
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2013-11-23 18:21:01 -08:00
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block: trace completion of all bios.
Currently only dm and md/raid5 bios trigger
trace_block_bio_complete(). Now that we have bio_chain() and
bio_inc_remaining(), it is not possible, in general, for a driver to
know when the bio is really complete. Only bio_endio() knows that.
So move the trace_block_bio_complete() call to bio_endio().
Now trace_block_bio_complete() pairs with trace_block_bio_queue().
Any bio for which a 'queue' event is traced, will subsequently
generate a 'complete' event.
There are a few cases where completion tracing is not wanted.
1/ If blk_update_request() has already generated a completion
trace event at the 'request' level, there is no point generating
one at the bio level too. In this case the bi_sector and bi_size
will have changed, so the bio level event would be wrong
2/ If the bio hasn't actually been queued yet, but is being aborted
early, then a trace event could be confusing. Some filesystems
call bio_endio() but do not want tracing.
3/ The bio_integrity code interposes itself by replacing bi_end_io,
then restoring it and calling bio_endio() again. This would produce
two identical trace events if left like that.
To handle these, we introduce a flag BIO_TRACE_COMPLETION and only
produce the trace event when this is set.
We address point 1 above by clearing the flag in blk_update_request().
We address point 2 above by only setting the flag when
generic_make_request() is called.
We address point 3 above by clearing the flag after generating a
completion event.
When bio_split() is used on a bio, particularly in blk_queue_split(),
there is an extra complication. A new bio is split off the front, and
may be handle directly without going through generic_make_request().
The old bio, which has been advanced, is passed to
generic_make_request(), so it will trigger a trace event a second
time.
Probably the best result when a split happens is to see a single
'queue' event for the whole bio, then multiple 'complete' events - one
for each component. To achieve this was can:
- copy the BIO_TRACE_COMPLETION flag to the new bio in bio_split()
- avoid generating a 'queue' event if BIO_TRACE_COMPLETION is already set.
This way, the split-off bio won't create a queue event, the original
won't either even if it re-submitted to generic_make_request(),
but both will produce completion events, each for their own range.
So if generic_make_request() is called (which generates a QUEUED
event), then bi_endio() will create a single COMPLETE event for each
range that the bio is split into, unless the driver has explicitly
requested it not to.
Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2017-04-07 09:40:52 -06:00
|
|
|
|
2018-01-23 09:10:19 -07:00
|
|
|
|
block: trace completion of all bios.
Currently only dm and md/raid5 bios trigger
trace_block_bio_complete(). Now that we have bio_chain() and
bio_inc_remaining(), it is not possible, in general, for a driver to
know when the bio is really complete. Only bio_endio() knows that.
So move the trace_block_bio_complete() call to bio_endio().
Now trace_block_bio_complete() pairs with trace_block_bio_queue().
Any bio for which a 'queue' event is traced, will subsequently
generate a 'complete' event.
There are a few cases where completion tracing is not wanted.
1/ If blk_update_request() has already generated a completion
trace event at the 'request' level, there is no point generating
one at the bio level too. In this case the bi_sector and bi_size
will have changed, so the bio level event would be wrong
2/ If the bio hasn't actually been queued yet, but is being aborted
early, then a trace event could be confusing. Some filesystems
call bio_endio() but do not want tracing.
3/ The bio_integrity code interposes itself by replacing bi_end_io,
then restoring it and calling bio_endio() again. This would produce
two identical trace events if left like that.
To handle these, we introduce a flag BIO_TRACE_COMPLETION and only
produce the trace event when this is set.
We address point 1 above by clearing the flag in blk_update_request().
We address point 2 above by only setting the flag when
generic_make_request() is called.
We address point 3 above by clearing the flag after generating a
completion event.
When bio_split() is used on a bio, particularly in blk_queue_split(),
there is an extra complication. A new bio is split off the front, and
may be handle directly without going through generic_make_request().
The old bio, which has been advanced, is passed to
generic_make_request(), so it will trigger a trace event a second
time.
Probably the best result when a split happens is to see a single
'queue' event for the whole bio, then multiple 'complete' events - one
for each component. To achieve this was can:
- copy the BIO_TRACE_COMPLETION flag to the new bio in bio_split()
- avoid generating a 'queue' event if BIO_TRACE_COMPLETION is already set.
This way, the split-off bio won't create a queue event, the original
won't either even if it re-submitted to generic_make_request(),
but both will produce completion events, each for their own range.
So if generic_make_request() is called (which generates a QUEUED
event), then bi_endio() will create a single COMPLETE event for each
range that the bio is split into, unless the driver has explicitly
requested it not to.
Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
2017-04-07 09:40:52 -06:00
|
|
|
|
2013-11-23 18:21:01 -08:00
|
|
|
|
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2013-08-07 11:14:32 -07:00
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2013-10-11 15:44:27 -07:00
|
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2013-08-07 11:14:32 -07:00
|
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|
2015-07-24 12:37:59 -06:00
|
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|
2013-08-07 11:14:32 -07:00
|
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2013-10-11 15:44:27 -07:00
|
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2017-06-29 11:31:08 -07:00
|
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|
2017-06-29 11:31:10 -07:00
|
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2017-06-29 11:31:08 -07:00
|
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|
2013-08-07 11:14:32 -07:00
|
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2005-04-16 15:20:36 -07:00
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|
2014-04-22 15:09:05 -06:00
|
|
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|
2005-04-16 15:20:36 -07:00
|
|
|
|
2016-07-19 11:28:42 +02:00
|
|
|
|
2005-04-16 15:20:36 -07:00
|
|
|
|
2012-10-12 15:29:33 -07:00
|
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|
2005-04-16 15:20:36 -07:00
|
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|
|
block: Avoid deadlocks with bio allocation by stacking drivers
Previously, if we ever try to allocate more than once from the same bio
set while running under generic_make_request() (i.e. a stacking block
driver), we risk deadlock.
This is because of the code in generic_make_request() that converts
recursion to iteration; any bios we submit won't actually be submitted
(so they can complete and eventually be freed) until after we return -
this means if we allocate a second bio, we're blocking the first one
from ever being freed.
Thus if enough threads call into a stacking block driver at the same
time with bios that need multiple splits, and the bio_set's reserve gets
used up, we deadlock.
This can be worked around in the driver code - we could check if we're
running under generic_make_request(), then mask out __GFP_WAIT when we
go to allocate a bio, and if the allocation fails punt to workqueue and
retry the allocation.
But this is tricky and not a generic solution. This patch solves it for
all users by inverting the previously described technique. We allocate a
rescuer workqueue for each bio_set, and then in the allocation code if
there are bios on current->bio_list we would be blocking, we punt them
to the rescuer workqueue to be submitted.
This guarantees forward progress for bio allocations under
generic_make_request() provided each bio is submitted before allocating
the next, and provided the bios are freed after they complete.
Note that this doesn't do anything for allocation from other mempools.
Instead of allocating per bio data structures from a mempool, code
should use bio_set's front_pad.
Tested it by forcing the rescue codepath to be taken (by disabling the
first GFP_NOWAIT) attempt, and then ran it with bcache (which does a lot
of arbitrary bio splitting) and verified that the rescuer was being
invoked.
Signed-off-by: Kent Overstreet <koverstreet@google.com>
CC: Jens Axboe <axboe@kernel.dk>
Acked-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Muthukumar Ratty <muthur@gmail.com>
2012-09-10 14:33:46 -07:00
|
|
|
|
|
|
|
|
|
|
|
|
|
|
2017-10-06 14:45:13 -04:00
|
|
|
|
|
|
|
|
|
2012-10-12 15:29:33 -07:00
|
|
|
|
2009-06-26 15:37:49 +02:00
|
|
|
|
2008-12-10 15:35:05 +01:00
|
|
|
|
2005-04-16 15:20:36 -07:00
|
|
|
|
|
|
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|
|
2009-09-26 16:19:21 +02:00
|
|
|
|
2005-04-16 15:20:36 -07:00
|
|
|
|
2017-06-18 14:38:57 +10:00
|
|
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2017-06-18 14:38:57 +10:00
|
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2017-06-18 14:38:57 +10:00
|
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2017-06-18 14:38:57 +10:00
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2017-06-18 14:38:57 +10:00
|
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2005-04-16 15:20:36 -07:00
|
|
|
|
2008-12-23 12:42:54 +01:00
|
|
|
|
2008-10-22 20:32:58 +02:00
|
|
|
|
2005-04-16 15:20:36 -07:00
|
|
|
|
2008-10-22 20:32:58 +02:00
|
|
|
|
2005-04-16 15:20:36 -07:00
|
|
|
|
|
|
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|
|
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|
2008-12-10 15:35:05 +01:00
|
|
|
|
2008-10-22 20:32:58 +02:00
|
|
|
|
block: Avoid deadlocks with bio allocation by stacking drivers
Previously, if we ever try to allocate more than once from the same bio
set while running under generic_make_request() (i.e. a stacking block
driver), we risk deadlock.
This is because of the code in generic_make_request() that converts
recursion to iteration; any bios we submit won't actually be submitted
(so they can complete and eventually be freed) until after we return -
this means if we allocate a second bio, we're blocking the first one
from ever being freed.
Thus if enough threads call into a stacking block driver at the same
time with bios that need multiple splits, and the bio_set's reserve gets
used up, we deadlock.
This can be worked around in the driver code - we could check if we're
running under generic_make_request(), then mask out __GFP_WAIT when we
go to allocate a bio, and if the allocation fails punt to workqueue and
retry the allocation.
But this is tricky and not a generic solution. This patch solves it for
all users by inverting the previously described technique. We allocate a
rescuer workqueue for each bio_set, and then in the allocation code if
there are bios on current->bio_list we would be blocking, we punt them
to the rescuer workqueue to be submitted.
This guarantees forward progress for bio allocations under
generic_make_request() provided each bio is submitted before allocating
the next, and provided the bios are freed after they complete.
Note that this doesn't do anything for allocation from other mempools.
Instead of allocating per bio data structures from a mempool, code
should use bio_set's front_pad.
Tested it by forcing the rescue codepath to be taken (by disabling the
first GFP_NOWAIT) attempt, and then ran it with bcache (which does a lot
of arbitrary bio splitting) and verified that the rescuer was being
invoked.
Signed-off-by: Kent Overstreet <koverstreet@google.com>
CC: Jens Axboe <axboe@kernel.dk>
Acked-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Muthukumar Ratty <muthur@gmail.com>
2012-09-10 14:33:46 -07:00
|
|
|
|
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|
|
|
|
|
|
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|
|
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|
|
|
|
2008-12-23 12:42:54 +01:00
|
|
|
|
2008-12-10 15:35:05 +01:00
|
|
|
|
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2005-04-16 15:20:36 -07:00
|
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|
2017-06-18 14:38:57 +10:00
|
|
|
|
2014-10-03 17:27:12 -04:00
|
|
|
|
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|
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|
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|
block: Avoid deadlocks with bio allocation by stacking drivers
Previously, if we ever try to allocate more than once from the same bio
set while running under generic_make_request() (i.e. a stacking block
driver), we risk deadlock.
This is because of the code in generic_make_request() that converts
recursion to iteration; any bios we submit won't actually be submitted
(so they can complete and eventually be freed) until after we return -
this means if we allocate a second bio, we're blocking the first one
from ever being freed.
Thus if enough threads call into a stacking block driver at the same
time with bios that need multiple splits, and the bio_set's reserve gets
used up, we deadlock.
This can be worked around in the driver code - we could check if we're
running under generic_make_request(), then mask out __GFP_WAIT when we
go to allocate a bio, and if the allocation fails punt to workqueue and
retry the allocation.
But this is tricky and not a generic solution. This patch solves it for
all users by inverting the previously described technique. We allocate a
rescuer workqueue for each bio_set, and then in the allocation code if
there are bios on current->bio_list we would be blocking, we punt them
to the rescuer workqueue to be submitted.
This guarantees forward progress for bio allocations under
generic_make_request() provided each bio is submitted before allocating
the next, and provided the bios are freed after they complete.
Note that this doesn't do anything for allocation from other mempools.
Instead of allocating per bio data structures from a mempool, code
should use bio_set's front_pad.
Tested it by forcing the rescue codepath to be taken (by disabling the
first GFP_NOWAIT) attempt, and then ran it with bcache (which does a lot
of arbitrary bio splitting) and verified that the rescuer was being
invoked.
Signed-off-by: Kent Overstreet <koverstreet@google.com>
CC: Jens Axboe <axboe@kernel.dk>
Acked-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Muthukumar Ratty <muthur@gmail.com>
2012-09-10 14:33:46 -07:00
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2017-06-18 14:38:57 +10:00
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block: Avoid deadlocks with bio allocation by stacking drivers
Previously, if we ever try to allocate more than once from the same bio
set while running under generic_make_request() (i.e. a stacking block
driver), we risk deadlock.
This is because of the code in generic_make_request() that converts
recursion to iteration; any bios we submit won't actually be submitted
(so they can complete and eventually be freed) until after we return -
this means if we allocate a second bio, we're blocking the first one
from ever being freed.
Thus if enough threads call into a stacking block driver at the same
time with bios that need multiple splits, and the bio_set's reserve gets
used up, we deadlock.
This can be worked around in the driver code - we could check if we're
running under generic_make_request(), then mask out __GFP_WAIT when we
go to allocate a bio, and if the allocation fails punt to workqueue and
retry the allocation.
But this is tricky and not a generic solution. This patch solves it for
all users by inverting the previously described technique. We allocate a
rescuer workqueue for each bio_set, and then in the allocation code if
there are bios on current->bio_list we would be blocking, we punt them
to the rescuer workqueue to be submitted.
This guarantees forward progress for bio allocations under
generic_make_request() provided each bio is submitted before allocating
the next, and provided the bios are freed after they complete.
Note that this doesn't do anything for allocation from other mempools.
Instead of allocating per bio data structures from a mempool, code
should use bio_set's front_pad.
Tested it by forcing the rescue codepath to be taken (by disabling the
first GFP_NOWAIT) attempt, and then ran it with bcache (which does a lot
of arbitrary bio splitting) and verified that the rescuer was being
invoked.
Signed-off-by: Kent Overstreet <koverstreet@google.com>
CC: Jens Axboe <axboe@kernel.dk>
Acked-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Muthukumar Ratty <muthur@gmail.com>
2012-09-10 14:33:46 -07:00
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2005-04-16 15:20:36 -07:00
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block: Avoid deadlocks with bio allocation by stacking drivers
Previously, if we ever try to allocate more than once from the same bio
set while running under generic_make_request() (i.e. a stacking block
driver), we risk deadlock.
This is because of the code in generic_make_request() that converts
recursion to iteration; any bios we submit won't actually be submitted
(so they can complete and eventually be freed) until after we return -
this means if we allocate a second bio, we're blocking the first one
from ever being freed.
Thus if enough threads call into a stacking block driver at the same
time with bios that need multiple splits, and the bio_set's reserve gets
used up, we deadlock.
This can be worked around in the driver code - we could check if we're
running under generic_make_request(), then mask out __GFP_WAIT when we
go to allocate a bio, and if the allocation fails punt to workqueue and
retry the allocation.
But this is tricky and not a generic solution. This patch solves it for
all users by inverting the previously described technique. We allocate a
rescuer workqueue for each bio_set, and then in the allocation code if
there are bios on current->bio_list we would be blocking, we punt them
to the rescuer workqueue to be submitted.
This guarantees forward progress for bio allocations under
generic_make_request() provided each bio is submitted before allocating
the next, and provided the bios are freed after they complete.
Note that this doesn't do anything for allocation from other mempools.
Instead of allocating per bio data structures from a mempool, code
should use bio_set's front_pad.
Tested it by forcing the rescue codepath to be taken (by disabling the
first GFP_NOWAIT) attempt, and then ran it with bcache (which does a lot
of arbitrary bio splitting) and verified that the rescuer was being
invoked.
Signed-off-by: Kent Overstreet <koverstreet@google.com>
CC: Jens Axboe <axboe@kernel.dk>
Acked-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Muthukumar Ratty <muthur@gmail.com>
2012-09-10 14:33:46 -07:00
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2005-04-16 15:20:36 -07:00
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2009-09-26 16:19:21 +02:00
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2005-04-16 15:20:36 -07:00
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2012-03-05 13:15:27 -08:00
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2015-05-22 17:13:24 -04:00
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2015-07-23 14:27:09 -04:00
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2015-05-22 17:13:24 -04:00
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2012-03-05 13:15:27 -08:00
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2016-07-27 07:22:05 +02:00
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2017-08-18 10:27:59 -07:00
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2012-03-05 13:15:27 -08:00
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2005-04-16 15:20:36 -07:00
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2016-07-19 11:28:42 +02:00
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2005-04-16 15:20:36 -07:00
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2008-12-05 16:10:29 +01:00
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2005-04-16 15:20:36 -07:00
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2007-07-20 10:11:58 +09:00
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2005-04-16 15:20:36 -07:00
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2008-12-10 15:35:05 +01:00
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2005-04-16 15:20:36 -07:00
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2009-06-26 15:37:49 +02:00
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2005-04-16 15:20:36 -07:00
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2017-06-18 14:38:57 +10:00
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2005-04-16 15:20:36 -07:00
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2011-03-17 11:11:05 +01:00
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2005-04-16 15:20:36 -07:00
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