2013-07-01 13:04:49 -07:00
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2005-04-16 15:20:36 -07:00
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2006-12-06 20:36:38 -08:00
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2005-04-16 15:20:36 -07:00
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2012-05-10 04:30:45 +02:00
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2016-10-18 10:12:27 -02:00
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2005-04-16 15:20:36 -07:00
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2016-12-12 16:45:56 -08:00
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2016-12-19 16:23:15 -08:00
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2016-12-12 16:45:56 -08:00
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2014-08-06 16:09:01 -07:00
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2011-03-22 16:34:23 -07:00
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2016-12-12 16:45:56 -08:00
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2013-07-01 13:04:49 -07:00
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2013-07-01 13:04:46 -07:00
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2014-02-04 12:20:01 -08:00
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2013-07-01 13:04:46 -07:00
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2014-07-30 20:50:18 +02:00
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2017-01-10 16:57:45 -08:00
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2014-07-30 20:50:18 +02:00
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2014-07-30 20:50:19 +02:00
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2015-02-17 13:46:36 -08:00
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2016-12-14 15:05:40 -08:00
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2015-02-17 13:46:36 -08:00
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2007-10-25 04:06:13 -04:00
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2006-08-14 22:43:18 -07:00
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2005-04-16 15:20:36 -07:00
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2008-02-22 15:15:03 +01:00
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2015-10-22 13:32:24 -07:00
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2016-10-27 17:46:41 -07:00
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2008-02-22 15:15:03 +01:00
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2009-09-18 12:49:22 -07:00
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2012-03-28 11:51:18 -07:00
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2006-06-28 04:26:45 -07:00
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mm/page_owner: keep track of page owners
This is the page owner tracking code which is introduced so far ago. It
is resident on Andrew's tree, though, nobody tried to upstream so it
remain as is. Our company uses this feature actively to debug memory leak
or to find a memory hogger so I decide to upstream this feature.
This functionality help us to know who allocates the page. When
allocating a page, we store some information about allocation in extra
memory. Later, if we need to know status of all pages, we can get and
analyze it from this stored information.
In previous version of this feature, extra memory is statically defined in
struct page, but, in this version, extra memory is allocated outside of
struct page. It enables us to turn on/off this feature at boottime
without considerable memory waste.
Although we already have tracepoint for tracing page allocation/free,
using it to analyze page owner is rather complex. We need to enlarge the
trace buffer for preventing overlapping until userspace program launched.
And, launched program continually dump out the trace buffer for later
analysis and it would change system behaviour with more possibility rather
than just keeping it in memory, so bad for debug.
Moreover, we can use page_owner feature further for various purposes. For
example, we can use it for fragmentation statistics implemented in this
patch. And, I also plan to implement some CMA failure debugging feature
using this interface.
I'd like to give the credit for all developers contributed this feature,
but, it's not easy because I don't know exact history. Sorry about that.
Below is people who has "Signed-off-by" in the patches in Andrew's tree.
Contributor:
Alexander Nyberg <alexn@dsv.su.se>
Mel Gorman <mgorman@suse.de>
Dave Hansen <dave@linux.vnet.ibm.com>
Minchan Kim <minchan@kernel.org>
Michal Nazarewicz <mina86@mina86.com>
Andrew Morton <akpm@linux-foundation.org>
Jungsoo Son <jungsoo.son@lge.com>
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Dave Hansen <dave@sr71.net>
Cc: Michal Nazarewicz <mina86@mina86.com>
Cc: Jungsoo Son <jungsoo.son@lge.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-12-12 16:56:01 -08:00
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mm/page_owner: use stackdepot to store stacktrace
Currently, we store each page's allocation stacktrace on corresponding
page_ext structure and it requires a lot of memory. This causes the
problem that memory tight system doesn't work well if page_owner is
enabled. Moreover, even with this large memory consumption, we cannot
get full stacktrace because we allocate memory at boot time and just
maintain 8 stacktrace slots to balance memory consumption. We could
increase it to more but it would make system unusable or change system
behaviour.
To solve the problem, this patch uses stackdepot to store stacktrace.
It obviously provides memory saving but there is a drawback that
stackdepot could fail.
stackdepot allocates memory at runtime so it could fail if system has
not enough memory. But, most of allocation stack are generated at very
early time and there are much memory at this time. So, failure would
not happen easily. And, one failure means that we miss just one page's
allocation stacktrace so it would not be a big problem. In this patch,
when memory allocation failure happens, we store special stracktrace
handle to the page that is failed to save stacktrace. With it, user can
guess memory usage properly even if failure happens.
Memory saving looks as following. (4GB memory system with page_owner)
(before the patch -> after the patch)
static allocation:
92274688 bytes -> 25165824 bytes
dynamic allocation after boot + kernel build:
0 bytes -> 327680 bytes
total:
92274688 bytes -> 25493504 bytes
72% reduction in total.
Note that implementation looks complex than someone would imagine
because there is recursion issue. stackdepot uses page allocator and
page_owner is called at page allocation. Using stackdepot in page_owner
could re-call page allcator and then page_owner. That is a recursion.
To detect and avoid it, whenever we obtain stacktrace, recursion is
checked and page_owner is set to dummy information if found. Dummy
information means that this page is allocated for page_owner feature
itself (such as stackdepot) and it's understandable behavior for user.
[iamjoonsoo.kim@lge.com: mm-page_owner-use-stackdepot-to-store-stacktrace-v3]
Link: http://lkml.kernel.org/r/1464230275-25791-6-git-send-email-iamjoonsoo.kim@lge.com
Link: http://lkml.kernel.org/r/1466150259-27727-7-git-send-email-iamjoonsoo.kim@lge.com
Link: http://lkml.kernel.org/r/1464230275-25791-6-git-send-email-iamjoonsoo.kim@lge.com
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Alexander Potapenko <glider@google.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-07-26 15:23:55 -07:00
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|
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|
mm/page_owner: keep track of page owners
This is the page owner tracking code which is introduced so far ago. It
is resident on Andrew's tree, though, nobody tried to upstream so it
remain as is. Our company uses this feature actively to debug memory leak
or to find a memory hogger so I decide to upstream this feature.
This functionality help us to know who allocates the page. When
allocating a page, we store some information about allocation in extra
memory. Later, if we need to know status of all pages, we can get and
analyze it from this stored information.
In previous version of this feature, extra memory is statically defined in
struct page, but, in this version, extra memory is allocated outside of
struct page. It enables us to turn on/off this feature at boottime
without considerable memory waste.
Although we already have tracepoint for tracing page allocation/free,
using it to analyze page owner is rather complex. We need to enlarge the
trace buffer for preventing overlapping until userspace program launched.
And, launched program continually dump out the trace buffer for later
analysis and it would change system behaviour with more possibility rather
than just keeping it in memory, so bad for debug.
Moreover, we can use page_owner feature further for various purposes. For
example, we can use it for fragmentation statistics implemented in this
patch. And, I also plan to implement some CMA failure debugging feature
using this interface.
I'd like to give the credit for all developers contributed this feature,
but, it's not easy because I don't know exact history. Sorry about that.
Below is people who has "Signed-off-by" in the patches in Andrew's tree.
Contributor:
Alexander Nyberg <alexn@dsv.su.se>
Mel Gorman <mgorman@suse.de>
Dave Hansen <dave@linux.vnet.ibm.com>
Minchan Kim <minchan@kernel.org>
Michal Nazarewicz <mina86@mina86.com>
Andrew Morton <akpm@linux-foundation.org>
Jungsoo Son <jungsoo.son@lge.com>
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Dave Hansen <dave@sr71.net>
Cc: Michal Nazarewicz <mina86@mina86.com>
Cc: Jungsoo Son <jungsoo.son@lge.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-12-12 16:56:01 -08:00
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2006-12-10 02:18:37 -08:00
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debugfs: prevent access to possibly dead file_operations at file open
Nothing prevents a dentry found by path lookup before a return of
__debugfs_remove() to actually get opened after that return. Now, after
the return of __debugfs_remove(), there are no guarantees whatsoever
regarding the memory the corresponding inode's file_operations object
had been kept in.
Since __debugfs_remove() is seldomly invoked, usually from module exit
handlers only, the race is hard to trigger and the impact is very low.
A discussion of the problem outlined above as well as a suggested
solution can be found in the (sub-)thread rooted at
http://lkml.kernel.org/g/20130401203445.GA20862@ZenIV.linux.org.uk
("Yet another pipe related oops.")
Basically, Greg KH suggests to introduce an intermediate fops and
Al Viro points out that a pointer to the original ones may be stored in
->d_fsdata.
Follow this line of reasoning:
- Add SRCU as a reverse dependency of DEBUG_FS.
- Introduce a srcu_struct object for the debugfs subsystem.
- In debugfs_create_file(), store a pointer to the original
file_operations object in ->d_fsdata.
- Make debugfs_remove() and debugfs_remove_recursive() wait for a
SRCU grace period after the dentry has been delete()'d and before they
return to their callers.
- Introduce an intermediate file_operations object named
"debugfs_open_proxy_file_operations". It's ->open() functions checks,
under the protection of a SRCU read lock, whether the dentry is still
alive, i.e. has not been d_delete()'d and if so, tries to acquire a
reference on the owning module.
On success, it sets the file object's ->f_op to the original
file_operations and forwards the ongoing open() call to the original
->open().
- For clarity, rename the former debugfs_file_operations to
debugfs_noop_file_operations -- they are in no way canonical.
The choice of SRCU over "normal" RCU is justified by the fact, that the
former may also be used to protect ->i_private data from going away
during the execution of a file's readers and writers which may (and do)
sleep.
Finally, introduce the fs/debugfs/internal.h header containing some
declarations internal to the debugfs implementation.
Signed-off-by: Nicolai Stange <nicstange@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2016-03-22 14:11:13 +01:00
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2006-12-10 02:18:37 -08:00
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2008-05-20 00:06:00 +02:00
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2006-12-10 02:18:37 -08:00
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2008-01-21 21:31:44 +01:00
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2011-04-17 04:08:48 +00:00
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2008-01-21 21:31:44 +01:00
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2011-04-17 04:08:48 +00:00
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2013-06-19 14:53:51 -04:00
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2008-01-30 11:13:23 +01:00
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2011-04-17 04:08:48 +00:00
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2008-01-21 21:31:44 +01:00
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2011-04-17 04:08:48 +00:00
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2016-09-09 10:04:58 +02:00
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2008-01-21 21:31:44 +01:00
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2011-04-17 04:08:48 +00:00
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2008-01-21 21:31:44 +01:00
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2015-10-06 09:44:42 +10:30
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2013-07-01 13:04:46 -07:00
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2006-01-09 20:54:51 -08:00
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2013-07-01 13:04:46 -07:00
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2007-02-12 00:52:00 -08:00
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2013-07-01 13:04:46 -07:00
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2007-02-12 00:52:00 -08:00
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2016-02-28 22:22:42 -06:00
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2013-07-01 13:04:46 -07:00
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2005-09-06 15:16:27 -07:00
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2013-07-01 13:04:46 -07:00
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2005-09-06 15:16:27 -07:00
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2013-07-01 13:04:46 -07:00
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2005-09-06 15:16:27 -07:00
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2013-07-01 13:04:46 -07:00
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2012-02-09 17:42:21 -05:00
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2013-07-01 13:04:46 -07:00
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2005-09-06 15:16:27 -07:00
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2013-07-01 13:04:46 -07:00
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2005-09-06 15:16:27 -07:00
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2013-10-07 01:05:46 +01:00
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2006-01-09 20:54:51 -08:00
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2011-03-22 16:34:16 -07:00
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2006-01-09 20:54:51 -08:00
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2011-03-22 16:34:16 -07:00
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2013-07-01 13:04:43 -07:00
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2011-03-22 16:34:16 -07:00
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2013-07-01 13:04:43 -07:00
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2011-03-22 16:34:16 -07:00
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2013-07-01 13:04:43 -07:00
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2008-05-12 21:21:04 +02:00
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2013-07-01 13:04:43 -07:00
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2008-05-12 21:21:04 +02:00
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2013-07-01 13:04:43 -07:00
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2008-05-12 21:21:04 +02:00
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2013-07-01 13:04:43 -07:00
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2008-04-30 00:55:01 -07:00
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2008-04-30 00:55:03 -07:00
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2009-11-16 01:09:48 +09:00
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2010-04-17 08:48:42 -04:00
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2011-02-23 09:42:14 -08:00
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2010-04-17 08:48:42 -04:00
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2010-10-26 14:23:05 -07:00
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2008-11-26 10:02:00 +01:00
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2005-04-16 15:20:36 -07:00
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2006-03-25 03:07:22 -08:00
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2008-04-04 00:51:41 +02:00
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2005-04-16 15:20:36 -07:00
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2006-03-25 03:06:39 -08:00
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2007-07-15 23:38:14 -07:00
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2008-04-04 00:51:41 +02:00
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2007-07-15 23:38:14 -07:00
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2008-02-07 17:47:41 -08:00
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2010-10-05 13:57:26 -05:00
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2008-02-07 17:47:41 -08:00
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2012-10-08 16:28:11 -07:00
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2009-06-11 13:24:13 +01:00
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2013-01-16 18:54:16 -08:00
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2011-04-27 17:06:19 +01:00
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2009-06-11 13:24:13 +01:00
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2009-11-06 15:33:45 -08:00
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2009-06-11 13:24:13 +01:00
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2016-12-14 15:05:40 -08:00
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2009-06-11 13:24:13 +01:00
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2013-07-01 13:04:43 -07:00
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2016-03-19 17:54:10 +01:00
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2013-07-01 13:04:43 -07:00
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2014-06-04 16:06:46 -07:00
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2013-07-01 13:04:43 -07:00
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2014-04-18 15:07:22 -07:00
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2013-07-01 13:04:43 -07:00
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2016-01-15 16:51:21 -08:00
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2013-07-01 13:04:43 -07:00
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2014-04-14 18:55:50 +02:00
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2013-07-01 13:04:43 -07:00
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2015-01-25 19:50:34 +01:00
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2013-07-01 13:04:43 -07:00
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kasan: add kernel address sanitizer infrastructure
Kernel Address sanitizer (KASan) is a dynamic memory error detector. It
provides fast and comprehensive solution for finding use-after-free and
out-of-bounds bugs.
KASAN uses compile-time instrumentation for checking every memory access,
therefore GCC > v4.9.2 required. v4.9.2 almost works, but has issues with
putting symbol aliases into the wrong section, which breaks kasan
instrumentation of globals.
This patch only adds infrastructure for kernel address sanitizer. It's
not available for use yet. The idea and some code was borrowed from [1].
Basic idea:
The main idea of KASAN is to use shadow memory to record whether each byte
of memory is safe to access or not, and use compiler's instrumentation to
check the shadow memory on each memory access.
Address sanitizer uses 1/8 of the memory addressable in kernel for shadow
memory and uses direct mapping with a scale and offset to translate a
memory address to its corresponding shadow address.
Here is function to translate address to corresponding shadow address:
unsigned long kasan_mem_to_shadow(unsigned long addr)
{
return (addr >> KASAN_SHADOW_SCALE_SHIFT) + KASAN_SHADOW_OFFSET;
}
where KASAN_SHADOW_SCALE_SHIFT = 3.
So for every 8 bytes there is one corresponding byte of shadow memory.
The following encoding used for each shadow byte: 0 means that all 8 bytes
of the corresponding memory region are valid for access; k (1 <= k <= 7)
means that the first k bytes are valid for access, and other (8 - k) bytes
are not; Any negative value indicates that the entire 8-bytes are
inaccessible. Different negative values used to distinguish between
different kinds of inaccessible memory (redzones, freed memory) (see
mm/kasan/kasan.h).
To be able to detect accesses to bad memory we need a special compiler.
Such compiler inserts a specific function calls (__asan_load*(addr),
__asan_store*(addr)) before each memory access of size 1, 2, 4, 8 or 16.
These functions check whether memory region is valid to access or not by
checking corresponding shadow memory. If access is not valid an error
printed.
Historical background of the address sanitizer from Dmitry Vyukov:
"We've developed the set of tools, AddressSanitizer (Asan),
ThreadSanitizer and MemorySanitizer, for user space. We actively use
them for testing inside of Google (continuous testing, fuzzing,
running prod services). To date the tools have found more than 10'000
scary bugs in Chromium, Google internal codebase and various
open-source projects (Firefox, OpenSSL, gcc, clang, ffmpeg, MySQL and
lots of others): [2] [3] [4].
The tools are part of both gcc and clang compilers.
We have not yet done massive testing under the Kernel AddressSanitizer
(it's kind of chicken and egg problem, you need it to be upstream to
start applying it extensively). To date it has found about 50 bugs.
Bugs that we've found in upstream kernel are listed in [5].
We've also found ~20 bugs in out internal version of the kernel. Also
people from Samsung and Oracle have found some.
[...]
As others noted, the main feature of AddressSanitizer is its
performance due to inline compiler instrumentation and simple linear
shadow memory. User-space Asan has ~2x slowdown on computational
programs and ~2x memory consumption increase. Taking into account that
kernel usually consumes only small fraction of CPU and memory when
running real user-space programs, I would expect that kernel Asan will
have ~10-30% slowdown and similar memory consumption increase (when we
finish all tuning).
I agree that Asan can well replace kmemcheck. We have plans to start
working on Kernel MemorySanitizer that finds uses of unitialized
memory. Asan+Msan will provide feature-parity with kmemcheck. As
others noted, Asan will unlikely replace debug slab and pagealloc that
can be enabled at runtime. Asan uses compiler instrumentation, so even
if it is disabled, it still incurs visible overheads.
Asan technology is easily portable to other architectures. Compiler
instrumentation is fully portable. Runtime has some arch-dependent
parts like shadow mapping and atomic operation interception. They are
relatively easy to port."
Comparison with other debugging features:
========================================
KMEMCHECK:
- KASan can do almost everything that kmemcheck can. KASan uses
compile-time instrumentation, which makes it significantly faster than
kmemcheck. The only advantage of kmemcheck over KASan is detection of
uninitialized memory reads.
Some brief performance testing showed that kasan could be
x500-x600 times faster than kmemcheck:
$ netperf -l 30
MIGRATED TCP STREAM TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to localhost (127.0.0.1) port 0 AF_INET
Recv Send Send
Socket Socket Message Elapsed
Size Size Size Time Throughput
bytes bytes bytes secs. 10^6bits/sec
no debug: 87380 16384 16384 30.00 41624.72
kasan inline: 87380 16384 16384 30.00 12870.54
kasan outline: 87380 16384 16384 30.00 10586.39
kmemcheck: 87380 16384 16384 30.03 20.23
- Also kmemcheck couldn't work on several CPUs. It always sets
number of CPUs to 1. KASan doesn't have such limitation.
DEBUG_PAGEALLOC:
- KASan is slower than DEBUG_PAGEALLOC, but KASan works on sub-page
granularity level, so it able to find more bugs.
SLUB_DEBUG (poisoning, redzones):
- SLUB_DEBUG has lower overhead than KASan.
- SLUB_DEBUG in most cases are not able to detect bad reads,
KASan able to detect both reads and writes.
- In some cases (e.g. redzone overwritten) SLUB_DEBUG detect
bugs only on allocation/freeing of object. KASan catch
bugs right before it will happen, so we always know exact
place of first bad read/write.
[1] https://code.google.com/p/address-sanitizer/wiki/AddressSanitizerForKernel
[2] https://code.google.com/p/address-sanitizer/wiki/FoundBugs
[3] https://code.google.com/p/thread-sanitizer/wiki/FoundBugs
[4] https://code.google.com/p/memory-sanitizer/wiki/FoundBugs
[5] https://code.google.com/p/address-sanitizer/wiki/AddressSanitizerForKernel#Trophies
Based on work by Andrey Konovalov.
Signed-off-by: Andrey Ryabinin <a.ryabinin@samsung.com>
Acked-by: Michal Marek <mmarek@suse.cz>
Signed-off-by: Andrey Konovalov <adech.fo@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Konstantin Serebryany <kcc@google.com>
Cc: Dmitry Chernenkov <dmitryc@google.com>
Cc: Yuri Gribov <tetra2005@gmail.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-13 14:39:17 -08:00
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2013-07-01 13:04:43 -07:00
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kernel: add kcov code coverage
kcov provides code coverage collection for coverage-guided fuzzing
(randomized testing). Coverage-guided fuzzing is a testing technique
that uses coverage feedback to determine new interesting inputs to a
system. A notable user-space example is AFL
(http://lcamtuf.coredump.cx/afl/). However, this technique is not
widely used for kernel testing due to missing compiler and kernel
support.
kcov does not aim to collect as much coverage as possible. It aims to
collect more or less stable coverage that is function of syscall inputs.
To achieve this goal it does not collect coverage in soft/hard
interrupts and instrumentation of some inherently non-deterministic or
non-interesting parts of kernel is disbled (e.g. scheduler, locking).
Currently there is a single coverage collection mode (tracing), but the
API anticipates additional collection modes. Initially I also
implemented a second mode which exposes coverage in a fixed-size hash
table of counters (what Quentin used in his original patch). I've
dropped the second mode for simplicity.
This patch adds the necessary support on kernel side. The complimentary
compiler support was added in gcc revision 231296.
We've used this support to build syzkaller system call fuzzer, which has
found 90 kernel bugs in just 2 months:
https://github.com/google/syzkaller/wiki/Found-Bugs
We've also found 30+ bugs in our internal systems with syzkaller.
Another (yet unexplored) direction where kcov coverage would greatly
help is more traditional "blob mutation". For example, mounting a
random blob as a filesystem, or receiving a random blob over wire.
Why not gcov. Typical fuzzing loop looks as follows: (1) reset
coverage, (2) execute a bit of code, (3) collect coverage, repeat. A
typical coverage can be just a dozen of basic blocks (e.g. an invalid
input). In such context gcov becomes prohibitively expensive as
reset/collect coverage steps depend on total number of basic
blocks/edges in program (in case of kernel it is about 2M). Cost of
kcov depends only on number of executed basic blocks/edges. On top of
that, kernel requires per-thread coverage because there are always
background threads and unrelated processes that also produce coverage.
With inlined gcov instrumentation per-thread coverage is not possible.
kcov exposes kernel PCs and control flow to user-space which is
insecure. But debugfs should not be mapped as user accessible.
Based on a patch by Quentin Casasnovas.
[akpm@linux-foundation.org: make task_struct.kcov_mode have type `enum kcov_mode']
[akpm@linux-foundation.org: unbreak allmodconfig]
[akpm@linux-foundation.org: follow x86 Makefile layout standards]
Signed-off-by: Dmitry Vyukov <dvyukov@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Cc: syzkaller <syzkaller@googlegroups.com>
Cc: Vegard Nossum <vegard.nossum@oracle.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Tavis Ormandy <taviso@google.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Quentin Casasnovas <quentin.casasnovas@oracle.com>
Cc: Kostya Serebryany <kcc@google.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Kees Cook <keescook@google.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: David Drysdale <drysdale@google.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Kirill A. Shutemov <kirill@shutemov.name>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-03-22 14:27:30 -07:00
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2016-06-11 09:09:28 -07:00
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kernel: add kcov code coverage
kcov provides code coverage collection for coverage-guided fuzzing
(randomized testing). Coverage-guided fuzzing is a testing technique
that uses coverage feedback to determine new interesting inputs to a
system. A notable user-space example is AFL
(http://lcamtuf.coredump.cx/afl/). However, this technique is not
widely used for kernel testing due to missing compiler and kernel
support.
kcov does not aim to collect as much coverage as possible. It aims to
collect more or less stable coverage that is function of syscall inputs.
To achieve this goal it does not collect coverage in soft/hard
interrupts and instrumentation of some inherently non-deterministic or
non-interesting parts of kernel is disbled (e.g. scheduler, locking).
Currently there is a single coverage collection mode (tracing), but the
API anticipates additional collection modes. Initially I also
implemented a second mode which exposes coverage in a fixed-size hash
table of counters (what Quentin used in his original patch). I've
dropped the second mode for simplicity.
This patch adds the necessary support on kernel side. The complimentary
compiler support was added in gcc revision 231296.
We've used this support to build syzkaller system call fuzzer, which has
found 90 kernel bugs in just 2 months:
https://github.com/google/syzkaller/wiki/Found-Bugs
We've also found 30+ bugs in our internal systems with syzkaller.
Another (yet unexplored) direction where kcov coverage would greatly
help is more traditional "blob mutation". For example, mounting a
random blob as a filesystem, or receiving a random blob over wire.
Why not gcov. Typical fuzzing loop looks as follows: (1) reset
coverage, (2) execute a bit of code, (3) collect coverage, repeat. A
typical coverage can be just a dozen of basic blocks (e.g. an invalid
input). In such context gcov becomes prohibitively expensive as
reset/collect coverage steps depend on total number of basic
blocks/edges in program (in case of kernel it is about 2M). Cost of
kcov depends only on number of executed basic blocks/edges. On top of
that, kernel requires per-thread coverage because there are always
background threads and unrelated processes that also produce coverage.
With inlined gcov instrumentation per-thread coverage is not possible.
kcov exposes kernel PCs and control flow to user-space which is
insecure. But debugfs should not be mapped as user accessible.
Based on a patch by Quentin Casasnovas.
[akpm@linux-foundation.org: make task_struct.kcov_mode have type `enum kcov_mode']
[akpm@linux-foundation.org: unbreak allmodconfig]
[akpm@linux-foundation.org: follow x86 Makefile layout standards]
Signed-off-by: Dmitry Vyukov <dvyukov@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Cc: syzkaller <syzkaller@googlegroups.com>
Cc: Vegard Nossum <vegard.nossum@oracle.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Tavis Ormandy <taviso@google.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Quentin Casasnovas <quentin.casasnovas@oracle.com>
Cc: Kostya Serebryany <kcc@google.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Kees Cook <keescook@google.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: David Drysdale <drysdale@google.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Kirill A. Shutemov <kirill@shutemov.name>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-03-22 14:27:30 -07:00
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2016-12-14 15:05:40 -08:00
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|
kernel: add kcov code coverage
kcov provides code coverage collection for coverage-guided fuzzing
(randomized testing). Coverage-guided fuzzing is a testing technique
that uses coverage feedback to determine new interesting inputs to a
system. A notable user-space example is AFL
(http://lcamtuf.coredump.cx/afl/). However, this technique is not
widely used for kernel testing due to missing compiler and kernel
support.
kcov does not aim to collect as much coverage as possible. It aims to
collect more or less stable coverage that is function of syscall inputs.
To achieve this goal it does not collect coverage in soft/hard
interrupts and instrumentation of some inherently non-deterministic or
non-interesting parts of kernel is disbled (e.g. scheduler, locking).
Currently there is a single coverage collection mode (tracing), but the
API anticipates additional collection modes. Initially I also
implemented a second mode which exposes coverage in a fixed-size hash
table of counters (what Quentin used in his original patch). I've
dropped the second mode for simplicity.
This patch adds the necessary support on kernel side. The complimentary
compiler support was added in gcc revision 231296.
We've used this support to build syzkaller system call fuzzer, which has
found 90 kernel bugs in just 2 months:
https://github.com/google/syzkaller/wiki/Found-Bugs
We've also found 30+ bugs in our internal systems with syzkaller.
Another (yet unexplored) direction where kcov coverage would greatly
help is more traditional "blob mutation". For example, mounting a
random blob as a filesystem, or receiving a random blob over wire.
Why not gcov. Typical fuzzing loop looks as follows: (1) reset
coverage, (2) execute a bit of code, (3) collect coverage, repeat. A
typical coverage can be just a dozen of basic blocks (e.g. an invalid
input). In such context gcov becomes prohibitively expensive as
reset/collect coverage steps depend on total number of basic
blocks/edges in program (in case of kernel it is about 2M). Cost of
kcov depends only on number of executed basic blocks/edges. On top of
that, kernel requires per-thread coverage because there are always
background threads and unrelated processes that also produce coverage.
With inlined gcov instrumentation per-thread coverage is not possible.
kcov exposes kernel PCs and control flow to user-space which is
insecure. But debugfs should not be mapped as user accessible.
Based on a patch by Quentin Casasnovas.
[akpm@linux-foundation.org: make task_struct.kcov_mode have type `enum kcov_mode']
[akpm@linux-foundation.org: unbreak allmodconfig]
[akpm@linux-foundation.org: follow x86 Makefile layout standards]
Signed-off-by: Dmitry Vyukov <dvyukov@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Cc: syzkaller <syzkaller@googlegroups.com>
Cc: Vegard Nossum <vegard.nossum@oracle.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Tavis Ormandy <taviso@google.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Quentin Casasnovas <quentin.casasnovas@oracle.com>
Cc: Kostya Serebryany <kcc@google.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Kees Cook <keescook@google.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: David Drysdale <drysdale@google.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Kirill A. Shutemov <kirill@shutemov.name>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-03-22 14:27:30 -07:00
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2016-08-02 14:07:30 -07:00
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2007-02-12 00:52:00 -08:00
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2013-08-30 09:39:53 +02:00
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2007-02-12 00:52:00 -08:00
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2013-07-01 13:04:50 -07:00
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2010-05-07 17:11:44 -04:00
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2006-10-11 01:20:44 -07:00
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2005-09-06 15:16:27 -07:00
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2010-05-07 17:11:44 -04:00
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2012-02-09 17:42:21 -05:00
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2010-05-07 17:11:44 -04:00
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2005-09-06 15:16:27 -07:00
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2010-05-07 17:11:44 -04:00
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2012-02-09 17:42:21 -05:00
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2010-05-07 17:11:44 -04:00
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2005-09-06 15:16:27 -07:00
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2010-05-07 17:11:44 -04:00
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2012-02-09 17:42:21 -05:00
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2005-09-06 15:16:27 -07:00
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2010-05-15 23:15:20 +02:00
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2012-10-04 17:13:17 -07:00
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2005-09-06 15:16:27 -07:00
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2011-03-22 16:34:16 -07:00
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2012-10-04 17:13:17 -07:00
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2011-03-22 16:34:16 -07:00
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2012-02-09 17:42:21 -05:00
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2011-03-22 16:34:16 -07:00
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2012-10-04 17:13:17 -07:00
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2011-03-22 16:34:16 -07:00
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2008-05-12 21:21:04 +02:00
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2010-05-13 00:27:20 +02:00
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2008-05-12 21:21:04 +02:00
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2012-02-09 17:42:21 -05:00
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2008-05-12 21:21:04 +02:00
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2010-05-15 22:30:22 +02:00
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2008-05-12 21:21:04 +02:00
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2009-01-15 11:08:40 -08:00
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2011-07-05 13:32:40 +10:00
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2009-01-15 11:08:40 -08:00
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2013-07-01 13:04:43 -07:00
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2016-09-22 16:55:13 -04:00
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2005-04-16 15:20:36 -07:00
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2013-07-01 13:04:43 -07:00
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2006-03-25 03:06:39 -08:00
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2013-07-01 13:04:43 -07:00
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2007-07-15 23:38:14 -07:00
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2013-07-01 13:04:43 -07:00
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2007-07-15 23:38:14 -07:00
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2013-07-01 13:04:43 -07:00
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2008-02-07 17:47:41 -08:00
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2013-07-01 13:04:43 -07:00
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2012-10-08 16:28:11 -07:00
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2013-07-01 13:04:43 -07:00
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2009-06-11 13:24:13 +01:00
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2013-07-01 13:04:43 -07:00
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2009-06-11 13:24:13 +01:00
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2013-07-01 13:04:43 -07:00
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2009-06-23 14:40:27 +01:00
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2013-07-01 13:04:43 -07:00
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2009-06-23 14:40:27 +01:00
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2013-07-01 13:04:43 -07:00
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2009-06-11 13:24:13 +01:00
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workqueue: implement lockup detector
Workqueue stalls can happen from a variety of usage bugs such as
missing WQ_MEM_RECLAIM flag or concurrency managed work item
indefinitely staying RUNNING. These stalls can be extremely difficult
to hunt down because the usual warning mechanisms can't detect
workqueue stalls and the internal state is pretty opaque.
To alleviate the situation, this patch implements workqueue lockup
detector. It periodically monitors all worker_pools periodically and,
if any pool failed to make forward progress longer than the threshold
duration, triggers warning and dumps workqueue state as follows.
BUG: workqueue lockup - pool cpus=0 node=0 flags=0x0 nice=0 stuck for 31s!
Showing busy workqueues and worker pools:
workqueue events: flags=0x0
pwq 0: cpus=0 node=0 flags=0x0 nice=0 active=17/256
pending: monkey_wrench_fn, e1000_watchdog, cache_reap, vmstat_shepherd, release_one_tty, release_one_tty, release_one_tty, release_one_tty, release_one_tty, release_one_tty, release_one_tty, release_one_tty, release_one_tty, release_one_tty, release_one_tty, release_one_tty, cgroup_release_agent
workqueue events_power_efficient: flags=0x80
pwq 0: cpus=0 node=0 flags=0x0 nice=0 active=2/256
pending: check_lifetime, neigh_periodic_work
workqueue cgroup_pidlist_destroy: flags=0x0
pwq 0: cpus=0 node=0 flags=0x0 nice=0 active=1/1
pending: cgroup_pidlist_destroy_work_fn
...
The detection mechanism is controller through kernel parameter
workqueue.watchdog_thresh and can be updated at runtime through the
sysfs module parameter file.
v2: Decoupled from softlockup control knobs.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Don Zickus <dzickus@redhat.com>
Cc: Ulrich Obergfell <uobergfe@redhat.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Chris Mason <clm@fb.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
2015-12-08 11:28:04 -05:00
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2013-07-01 13:04:50 -07:00
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2009-06-25 10:16:11 +01:00
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2013-07-01 13:04:50 -07:00
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2009-06-25 10:16:11 +01:00
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2013-07-01 13:04:50 -07:00
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2013-11-25 23:23:04 +00:00
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2013-07-01 13:04:43 -07:00
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2009-06-11 13:24:14 +01:00
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2013-07-01 13:04:43 -07:00
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2009-06-11 13:24:14 +01:00
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2015-06-25 23:53:37 +05:30
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2013-07-01 13:04:43 -07:00
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2015-06-25 23:53:37 +05:30
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2013-07-01 13:04:43 -07:00
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2009-06-11 13:24:14 +01:00
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2014-09-12 14:16:19 +01:00
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2015-03-11 21:16:32 -07:00
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2013-07-01 13:04:43 -07:00
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2010-07-19 11:54:17 +01:00
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2013-07-01 13:04:43 -07:00
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2010-07-19 11:54:17 +01:00
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2005-04-16 15:20:36 -07:00
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2009-10-16 07:21:39 +00:00
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2005-04-16 15:20:36 -07:00
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2013-07-01 13:04:47 -07:00
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2006-06-27 02:54:55 -07:00
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2005-04-16 15:20:36 -07:00
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2006-07-03 00:24:55 -07:00
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2005-04-16 15:20:36 -07:00
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2012-03-22 15:25:08 +05:30
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2005-04-16 15:20:36 -07:00
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2006-07-03 00:24:55 -07:00
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2013-06-20 13:31:17 +02:00
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2014-08-27 11:19:26 -04:00
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2013-06-20 13:31:17 +02:00
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2006-07-03 00:24:55 -07:00
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2006-07-14 00:24:32 -07:00
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2006-07-03 00:24:55 -07:00
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2006-07-14 00:24:32 -07:00
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2006-07-03 00:24:55 -07:00
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2010-08-31 16:35:20 -04:00
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2006-07-03 00:24:55 -07:00
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2014-07-30 13:41:55 -07:00
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2006-07-03 00:24:55 -07:00
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2016-11-02 09:36:32 -07:00
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2006-07-03 00:24:55 -07:00
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2006-07-14 00:24:32 -07:00
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2006-07-03 00:24:55 -07:00
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2014-06-23 13:22:04 -07:00
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2006-07-03 00:24:55 -07:00
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2007-07-19 01:48:56 -07:00
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2007-09-24 21:24:43 -07:00
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2007-07-19 01:48:56 -07:00
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2014-07-30 13:41:55 -07:00
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2007-10-07 00:24:33 -07:00
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2010-02-27 17:10:39 +01:00
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2010-02-04 16:08:15 +09:00
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2010-02-27 17:10:39 +01:00
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2010-02-04 16:08:15 +09:00
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2006-07-03 00:24:55 -07:00
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2006-07-14 00:24:32 -07:00
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2006-07-03 00:24:55 -07:00
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2011-06-08 19:31:56 +02:00
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2011-06-08 01:51:02 +02:00
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2005-04-16 15:20:36 -07:00
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2011-06-08 19:31:56 +02:00
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2005-04-16 15:20:36 -07:00
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2006-07-03 00:24:48 -07:00
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2014-02-04 15:51:41 -08:00
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2013-07-01 13:04:47 -07:00
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2006-07-03 00:24:38 -07:00
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2013-07-01 13:04:47 -07:00
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2011-05-24 17:13:36 -07:00
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2013-07-01 13:04:47 -07:00
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2011-05-24 17:13:36 -07:00
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2006-07-03 00:24:38 -07:00
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2014-08-29 15:18:35 -07:00
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2006-07-03 00:24:38 -07:00
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2014-08-29 15:18:35 -07:00
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2011-05-24 17:13:36 -07:00
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2005-04-16 15:20:36 -07:00
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2013-06-27 15:06:14 +01:00
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2013-10-29 08:33:36 -07:00
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2013-06-27 15:06:14 +01:00
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2012-10-08 16:28:13 -07:00
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2005-04-16 15:20:36 -07:00
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2011-01-20 14:44:16 -08:00
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2012-10-08 16:28:13 -07:00
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2009-12-14 18:00:25 -08:00
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2005-04-16 15:20:36 -07:00
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2006-09-29 01:59:00 -07:00
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2016-08-26 17:42:00 +02:00
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2006-09-29 01:59:00 -07:00
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2014-06-04 16:11:54 -07:00
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2007-10-22 20:01:06 +02:00
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2008-08-15 15:29:38 -07:00
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2009-09-02 09:13:40 +01:00
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2013-01-07 08:19:23 -08:00
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2015-01-18 18:01:21 -08:00
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2013-01-07 08:19:23 -08:00
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2014-01-27 11:49:39 -08:00
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2015-12-31 18:33:22 -08:00
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2005-10-30 15:03:12 -08:00
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2014-01-27 11:49:39 -08:00
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2014-12-05 11:24:45 -05:00
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2015-04-20 05:42:50 -07:00
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2005-10-30 15:03:12 -08:00
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2008-06-18 09:26:49 -07:00
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2005-10-30 15:03:12 -08:00
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2006-10-02 02:17:36 -07:00
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2015-03-10 18:33:20 -07:00
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2015-01-22 18:24:08 -08:00
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2015-03-10 18:33:20 -07:00
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2015-01-22 18:24:08 -08:00
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2015-01-29 16:37:19 -08:00
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2015-04-14 19:33:59 -07:00
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2015-01-22 18:24:08 -08:00
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2015-03-10 18:33:20 -07:00
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2010-06-02 16:21:38 -07:00
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2012-10-19 12:49:17 -07:00
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2010-06-02 16:21:38 -07:00
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2012-10-25 17:59:23 -07:00
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2010-06-02 16:21:38 -07:00
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2012-01-06 15:10:44 -08:00
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2008-01-30 13:33:08 +01:00
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2012-11-14 16:26:40 -08:00
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2008-01-30 13:33:08 +01:00
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2012-01-06 15:10:44 -08:00
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2016-10-06 05:42:39 -07:00
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2008-06-27 18:04:48 +02:00
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2012-01-06 15:10:44 -08:00
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2008-01-30 13:33:08 +01:00
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2015-05-05 23:04:22 -07:00
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2015-06-30 09:56:31 -07:00
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2015-05-05 23:04:22 -07:00
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2013-01-07 08:19:23 -08:00
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2016-02-09 17:59:38 -05:00
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2008-08-25 19:47:25 +09:00
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2008-08-29 09:06:29 +02:00
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2008-08-25 19:47:25 +09:00
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2008-10-13 10:46:01 +02:00
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2008-08-25 19:47:25 +09:00
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2008-09-01 13:44:35 +02:00
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2008-08-25 19:47:25 +09:00
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2016-02-26 18:43:32 +00:00
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2012-07-30 14:43:02 -07:00
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2012-11-30 16:44:39 +09:00
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2012-07-30 14:43:02 -07:00
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2012-07-30 14:43:07 -07:00
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2012-11-30 16:44:39 +09:00
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2012-07-30 14:43:07 -07:00
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2012-12-14 10:32:52 +11:00
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2012-07-30 14:43:13 -07:00
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2012-11-30 16:44:39 +09:00
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2012-12-14 10:32:52 +11:00
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2012-07-30 14:43:13 -07:00
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2012-12-14 10:32:52 +11:00
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2012-07-30 14:43:13 -07:00
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2013-04-30 15:28:49 -07:00
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2012-07-30 14:43:13 -07:00
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2015-11-28 13:45:28 +01:00
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2006-12-08 02:39:43 -08:00
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2006-12-08 02:39:49 -08:00
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2006-12-08 02:39:48 -08:00
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2006-12-08 02:39:43 -08:00
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2006-12-08 02:39:44 -08:00
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2006-12-08 02:39:49 -08:00
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2008-12-23 19:37:01 +09:00
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2006-12-08 02:39:44 -08:00
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2006-12-08 02:39:49 -08:00
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2006-12-08 02:39:44 -08:00
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2006-12-08 02:39:45 -08:00
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2006-12-08 02:39:49 -08:00
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2006-12-08 02:39:45 -08:00
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2006-12-08 02:39:49 -08:00
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2006-12-08 02:39:45 -08:00
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2006-12-08 02:39:46 -08:00
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2006-12-12 20:16:36 +01:00
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2008-09-14 05:56:33 -07:00
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2006-12-08 02:39:46 -08:00
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2006-12-08 02:39:49 -08:00
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2006-12-08 02:39:46 -08:00
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2008-09-14 05:56:33 -07:00
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2010-07-21 16:05:53 +09:00
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2008-09-14 05:56:33 -07:00
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2011-08-19 14:52:37 +02:00
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2015-11-10 20:12:19 +01:00
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2011-08-19 14:52:37 +02:00
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2015-06-29 23:26:02 -07:00
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2006-12-08 02:39:43 -08:00
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2006-12-08 02:39:49 -08:00
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2006-12-08 02:39:43 -08:00
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2006-12-08 02:39:49 -08:00
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2007-02-20 13:57:56 -08:00
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2007-05-12 10:36:53 -07:00
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2007-02-20 13:57:56 -08:00
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2014-06-23 13:22:04 -07:00
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2007-02-20 13:57:56 -08:00
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2007-10-18 23:41:07 -07:00
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2008-01-25 21:08:34 +01:00
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2010-08-12 12:31:21 -07:00
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2013-08-27 13:52:51 +05:30
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2008-01-25 21:08:34 +01:00
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2008-05-12 21:20:42 +02:00
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2013-07-01 13:04:44 -07:00
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2012-10-08 16:30:39 -07:00
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2013-09-11 14:25:19 -07:00
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2012-10-08 16:30:39 -07:00
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rbtree: add prio tree and interval tree tests
Patch 1 implements support for interval trees, on top of the augmented
rbtree API. It also adds synthetic tests to compare the performance of
interval trees vs prio trees. Short answers is that interval trees are
slightly faster (~25%) on insert/erase, and much faster (~2.4 - 3x)
on search. It is debatable how realistic the synthetic test is, and I have
not made such measurements yet, but my impression is that interval trees
would still come out faster.
Patch 2 uses a preprocessor template to make the interval tree generic,
and uses it as a replacement for the vma prio_tree.
Patch 3 takes the other prio_tree user, kmemleak, and converts it to use
a basic rbtree. We don't actually need the augmented rbtree support here
because the intervals are always non-overlapping.
Patch 4 removes the now-unused prio tree library.
Patch 5 proposes an additional optimization to rb_erase_augmented, now
providing it as an inline function so that the augmented callbacks can be
inlined in. This provides an additional 5-10% performance improvement
for the interval tree insert/erase benchmark. There is a maintainance cost
as it exposes augmented rbtree users to some of the rbtree library internals;
however I think this cost shouldn't be too high as I expect the augmented
rbtree will always have much less users than the base rbtree.
I should probably add a quick summary of why I think it makes sense to
replace prio trees with augmented rbtree based interval trees now. One of
the drivers is that we need augmented rbtrees for Rik's vma gap finding
code, and once you have them, it just makes sense to use them for interval
trees as well, as this is the simpler and more well known algorithm. prio
trees, in comparison, seem *too* clever: they impose an additional 'heap'
constraint on the tree, which they use to guarantee a faster worst-case
complexity of O(k+log N) for stabbing queries in a well-balanced prio
tree, vs O(k*log N) for interval trees (where k=number of matches,
N=number of intervals). Now this sounds great, but in practice prio trees
don't realize this theorical benefit. First, the additional constraint
makes them harder to update, so that the kernel implementation has to
simplify things by balancing them like a radix tree, which is not always
ideal. Second, the fact that there are both index and heap properties
makes both tree manipulation and search more complex, which results in a
higher multiplicative time constant. As it turns out, the simple interval
tree algorithm ends up running faster than the more clever prio tree.
This patch:
Add two test modules:
- prio_tree_test measures the performance of lib/prio_tree.c, both for
insertion/removal and for stabbing searches
- interval_tree_test measures the performance of a library of equivalent
functionality, built using the augmented rbtree support.
In order to support the second test module, lib/interval_tree.c is
introduced. It is kept separate from the interval_tree_test main file
for two reasons: first we don't want to provide an unfair advantage
over prio_tree_test by having everything in a single compilation unit,
and second there is the possibility that the interval tree functionality
could get some non-test users in kernel over time.
Signed-off-by: Michel Lespinasse <walken@google.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Hillf Danton <dhillf@gmail.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-10-08 16:31:23 -07:00
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2014-03-17 12:21:54 +00:00
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rbtree: add prio tree and interval tree tests
Patch 1 implements support for interval trees, on top of the augmented
rbtree API. It also adds synthetic tests to compare the performance of
interval trees vs prio trees. Short answers is that interval trees are
slightly faster (~25%) on insert/erase, and much faster (~2.4 - 3x)
on search. It is debatable how realistic the synthetic test is, and I have
not made such measurements yet, but my impression is that interval trees
would still come out faster.
Patch 2 uses a preprocessor template to make the interval tree generic,
and uses it as a replacement for the vma prio_tree.
Patch 3 takes the other prio_tree user, kmemleak, and converts it to use
a basic rbtree. We don't actually need the augmented rbtree support here
because the intervals are always non-overlapping.
Patch 4 removes the now-unused prio tree library.
Patch 5 proposes an additional optimization to rb_erase_augmented, now
providing it as an inline function so that the augmented callbacks can be
inlined in. This provides an additional 5-10% performance improvement
for the interval tree insert/erase benchmark. There is a maintainance cost
as it exposes augmented rbtree users to some of the rbtree library internals;
however I think this cost shouldn't be too high as I expect the augmented
rbtree will always have much less users than the base rbtree.
I should probably add a quick summary of why I think it makes sense to
replace prio trees with augmented rbtree based interval trees now. One of
the drivers is that we need augmented rbtrees for Rik's vma gap finding
code, and once you have them, it just makes sense to use them for interval
trees as well, as this is the simpler and more well known algorithm. prio
trees, in comparison, seem *too* clever: they impose an additional 'heap'
constraint on the tree, which they use to guarantee a faster worst-case
complexity of O(k+log N) for stabbing queries in a well-balanced prio
tree, vs O(k*log N) for interval trees (where k=number of matches,
N=number of intervals). Now this sounds great, but in practice prio trees
don't realize this theorical benefit. First, the additional constraint
makes them harder to update, so that the kernel implementation has to
simplify things by balancing them like a radix tree, which is not always
ideal. Second, the fact that there are both index and heap properties
makes both tree manipulation and search more complex, which results in a
higher multiplicative time constant. As it turns out, the simple interval
tree algorithm ends up running faster than the more clever prio tree.
This patch:
Add two test modules:
- prio_tree_test measures the performance of lib/prio_tree.c, both for
insertion/removal and for stabbing searches
- interval_tree_test measures the performance of a library of equivalent
functionality, built using the augmented rbtree support.
In order to support the second test module, lib/interval_tree.c is
introduced. It is kept separate from the interval_tree_test main file
for two reasons: first we don't want to provide an unfair advantage
over prio_tree_test by having everything in a single compilation unit,
and second there is the possibility that the interval tree functionality
could get some non-test users in kernel over time.
Signed-off-by: Michel Lespinasse <walken@google.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Hillf Danton <dhillf@gmail.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-10-08 16:31:23 -07:00
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2013-11-12 15:08:34 -08:00
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2013-07-01 13:04:44 -07:00
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2015-02-12 15:02:21 -08:00
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2013-07-01 13:04:44 -07:00
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2015-11-06 16:30:29 -08:00
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2016-02-19 09:24:00 -05:00
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2016-05-30 17:40:41 +03:00
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2014-08-02 11:47:44 +02:00
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2015-01-29 15:40:25 +01:00
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2014-08-02 11:47:44 +02:00
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2016-05-26 22:11:51 -04:00
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2013-07-01 13:04:44 -07:00
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x86: early boot debugging via FireWire (ohci1394_dma=early)
This patch adds a new configuration option, which adds support for a new
early_param which gets checked in arch/x86/kernel/setup_{32,64}.c:setup_arch()
to decide wether OHCI-1394 FireWire controllers should be initialized and
enabled for physical DMA access to allow remote debugging of early problems
like issues ACPI or other subsystems which are executed very early.
If the config option is not enabled, no code is changed, and if the boot
paramenter is not given, no new code is executed, and independent of that,
all new code is freed after boot, so the config option can be even enabled
in standard, non-debug kernels.
With specialized tools, it is then possible to get debugging information
from machines which have no serial ports (notebooks) such as the printk
buffer contents, or any data which can be referenced from global pointers,
if it is stored below the 4GB limit and even memory dumps of of the physical
RAM region below the 4GB limit can be taken without any cooperation from the
CPU of the host, so the machine can be crashed early, it does not matter.
In the extreme, even kernel debuggers can be accessed in this way. I wrote
a small kgdb module and an accompanying gdb stub for FireWire which allows
to gdb to talk to kgdb using remote remory reads and writes over FireWire.
An version of the gdb stub fore FireWire is able to read all global data
from a system which is running a a normal kernel without any kernel debugger,
without any interruption or support of the system's CPU. That way, e.g. the
task struct and so on can be read and even manipulated when the physical DMA
access is granted.
A HOWTO is included in this patch, in Documentation/debugging-via-ohci1394.txt
and I've put a copy online at
ftp://ftp.suse.de/private/bk/firewire/docs/debugging-via-ohci1394.txt
It also has links to all the tools which are available to make use of it
another copy of it is online at:
ftp://ftp.suse.de/private/bk/firewire/kernel/ohci1394_dma_early-v2.diff
Signed-Off-By: Bernhard Kaindl <bk@suse.de>
Tested-By: Thomas Renninger <trenn@suse.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-01-30 13:34:11 +01:00
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2008-02-28 20:54:43 +01:00
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x86: early boot debugging via FireWire (ohci1394_dma=early)
This patch adds a new configuration option, which adds support for a new
early_param which gets checked in arch/x86/kernel/setup_{32,64}.c:setup_arch()
to decide wether OHCI-1394 FireWire controllers should be initialized and
enabled for physical DMA access to allow remote debugging of early problems
like issues ACPI or other subsystems which are executed very early.
If the config option is not enabled, no code is changed, and if the boot
paramenter is not given, no new code is executed, and independent of that,
all new code is freed after boot, so the config option can be even enabled
in standard, non-debug kernels.
With specialized tools, it is then possible to get debugging information
from machines which have no serial ports (notebooks) such as the printk
buffer contents, or any data which can be referenced from global pointers,
if it is stored below the 4GB limit and even memory dumps of of the physical
RAM region below the 4GB limit can be taken without any cooperation from the
CPU of the host, so the machine can be crashed early, it does not matter.
In the extreme, even kernel debuggers can be accessed in this way. I wrote
a small kgdb module and an accompanying gdb stub for FireWire which allows
to gdb to talk to kgdb using remote remory reads and writes over FireWire.
An version of the gdb stub fore FireWire is able to read all global data
from a system which is running a a normal kernel without any kernel debugger,
without any interruption or support of the system's CPU. That way, e.g. the
task struct and so on can be read and even manipulated when the physical DMA
access is granted.
A HOWTO is included in this patch, in Documentation/debugging-via-ohci1394.txt
and I've put a copy online at
ftp://ftp.suse.de/private/bk/firewire/docs/debugging-via-ohci1394.txt
It also has links to all the tools which are available to make use of it
another copy of it is online at:
ftp://ftp.suse.de/private/bk/firewire/kernel/ohci1394_dma_early-v2.diff
Signed-Off-By: Bernhard Kaindl <bk@suse.de>
Tested-By: Thomas Renninger <trenn@suse.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-01-30 13:34:11 +01:00
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2008-01-25 21:08:34 +01:00
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2009-01-09 12:14:24 +01:00
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2014-01-21 15:48:12 -08:00
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driver core: basic infrastructure for per-module dynamic debug messages
Base infrastructure to enable per-module debug messages.
I've introduced CONFIG_DYNAMIC_PRINTK_DEBUG, which when enabled centralizes
control of debugging statements on a per-module basis in one /proc file,
currently, <debugfs>/dynamic_printk/modules. When, CONFIG_DYNAMIC_PRINTK_DEBUG,
is not set, debugging statements can still be enabled as before, often by
defining 'DEBUG' for the proper compilation unit. Thus, this patch set has no
affect when CONFIG_DYNAMIC_PRINTK_DEBUG is not set.
The infrastructure currently ties into all pr_debug() and dev_dbg() calls. That
is, if CONFIG_DYNAMIC_PRINTK_DEBUG is set, all pr_debug() and dev_dbg() calls
can be dynamically enabled/disabled on a per-module basis.
Future plans include extending this functionality to subsystems, that define
their own debug levels and flags.
Usage:
Dynamic debugging is controlled by the debugfs file,
<debugfs>/dynamic_printk/modules. This file contains a list of the modules that
can be enabled. The format of the file is as follows:
<module_name> <enabled=0/1>
.
.
.
<module_name> : Name of the module in which the debug call resides
<enabled=0/1> : whether the messages are enabled or not
For example:
snd_hda_intel enabled=0
fixup enabled=1
driver enabled=0
Enable a module:
$echo "set enabled=1 <module_name>" > dynamic_printk/modules
Disable a module:
$echo "set enabled=0 <module_name>" > dynamic_printk/modules
Enable all modules:
$echo "set enabled=1 all" > dynamic_printk/modules
Disable all modules:
$echo "set enabled=0 all" > dynamic_printk/modules
Finally, passing "dynamic_printk" at the command line enables
debugging for all modules. This mode can be turned off via the above
disable command.
[gkh: minor cleanups and tweaks to make the build work quietly]
Signed-off-by: Jason Baron <jbaron@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2008-08-12 16:46:19 -04:00
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2014-10-13 15:51:38 -07:00
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test: add minimal module for verification testing
This is a pair of test modules I'd like to see in the tree. Instead of
putting these in lkdtm, where I've been adding various tests that trigger
crashes, these don't make sense there since they need to be either
distinctly separate, or their pass/fail state don't need to crash the
machine.
These live in lib/ for now, along with a few other in-kernel test modules,
and use the slightly more common "test_" naming convention, instead of
"test-". We should likely standardize on the former:
$ find . -name 'test_*.c' | grep -v /tools/ | wc -l
4
$ find . -name 'test-*.c' | grep -v /tools/ | wc -l
2
The first is entirely a no-op module, designed to allow simple testing of
the module loading and verification interface. It's useful to have a
module that has no other uses or dependencies so it can be reliably used
for just testing module loading and verification.
The second is a module that exercises the user memory access functions, in
an effort to make sure that we can quickly catch any regressions in
boundary checking (e.g. like what was recently fixed on ARM).
This patch (of 2):
When doing module loading verification tests (for example, with module
signing, or LSM hooks), it is very handy to have a module that can be
built on all systems under test, isn't auto-loaded at boot, and has no
device or similar dependencies. This creates the "test_module.ko" module
for that purpose, which only reports its load and unload to printk.
Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Joe Perches <joe@perches.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-01-23 15:54:37 -08:00
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2014-01-23 15:54:38 -08:00
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2014-05-08 14:10:52 -07:00
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2014-05-13 09:58:44 -07:00
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2014-05-08 14:10:52 -07:00
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bpf: mini eBPF library, test stubs and verifier testsuite
1.
the library includes a trivial set of BPF syscall wrappers:
int bpf_create_map(int key_size, int value_size, int max_entries);
int bpf_update_elem(int fd, void *key, void *value);
int bpf_lookup_elem(int fd, void *key, void *value);
int bpf_delete_elem(int fd, void *key);
int bpf_get_next_key(int fd, void *key, void *next_key);
int bpf_prog_load(enum bpf_prog_type prog_type,
const struct sock_filter_int *insns, int insn_len,
const char *license);
bpf_prog_load() stores verifier log into global bpf_log_buf[] array
and BPF_*() macros to build instructions
2.
test stubs configure eBPF infra with 'unspec' map and program types.
These are fake types used by user space testsuite only.
3.
verifier tests valid and invalid programs and expects predefined
error log messages from kernel.
40 tests so far.
$ sudo ./test_verifier
#0 add+sub+mul OK
#1 unreachable OK
#2 unreachable2 OK
#3 out of range jump OK
#4 out of range jump2 OK
#5 test1 ld_imm64 OK
...
Signed-off-by: Alexei Starovoitov <ast@plumgrid.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2014-09-26 00:17:07 -07:00
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2014-05-08 14:10:52 -07:00
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2014-07-14 14:38:12 -07:00
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2014-06-16 14:58:32 -07:00
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2015-04-14 15:48:27 -07:00
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2015-04-14 15:48:40 -07:00
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2015-04-14 15:48:27 -07:00
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2015-08-03 11:42:57 +02:00
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2015-07-30 03:59:44 +00:00
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2015-08-03 11:42:57 +02:00
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2015-07-30 03:59:44 +00:00
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2016-08-17 14:42:11 -07:00
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2016-08-20 12:16:10 +02:00
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2016-08-17 14:42:11 -07:00
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2007-10-18 23:41:07 -07:00
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2008-04-17 20:05:37 +02:00
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2009-02-26 21:38:56 +02:00
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2016-01-20 15:00:55 -08:00
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2015-11-19 18:19:29 -08:00
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2016-12-12 16:46:14 -08:00
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2015-11-19 18:19:29 -08:00
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2015-11-23 15:49:03 -08:00
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2015-11-19 18:19:29 -08:00
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2015-11-23 15:49:03 -08:00
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2015-11-19 18:19:29 -08:00
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