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Matt Fleming 4c4e238d3a mm/page_alloc: let GFP_ATOMIC order-0 allocs access highatomic reserves 
[ Upstream commit 281dd25c1a ]

Under memory pressure it's possible for GFP_ATOMIC order-0 allocations to
fail even though free pages are available in the highatomic reserves.
GFP_ATOMIC allocations cannot trigger unreserve_highatomic_pageblock()
since it's only run from reclaim.

Given that such allocations will pass the watermarks in
__zone_watermark_unusable_free(), it makes sense to fallback to highatomic
reserves the same way that ALLOC_OOM can.

This fixes order-0 page allocation failures observed on Cloudflare's fleet
when handling network packets:

  kswapd1: page allocation failure: order:0, mode:0x820(GFP_ATOMIC),
  nodemask=(null),cpuset=/,mems_allowed=0-7
  CPU: 10 PID: 696 Comm: kswapd1 Kdump: loaded Tainted: G           O 6.6.43-CUSTOM #1
  Hardware name: MACHINE
  Call Trace:
   <IRQ>
   dump_stack_lvl+0x3c/0x50
   warn_alloc+0x13a/0x1c0
   __alloc_pages_slowpath.constprop.0+0xc9d/0xd10
   __alloc_pages+0x327/0x340
   __napi_alloc_skb+0x16d/0x1f0
   bnxt_rx_page_skb+0x96/0x1b0 [bnxt_en]
   bnxt_rx_pkt+0x201/0x15e0 [bnxt_en]
   __bnxt_poll_work+0x156/0x2b0 [bnxt_en]
   bnxt_poll+0xd9/0x1c0 [bnxt_en]
   __napi_poll+0x2b/0x1b0
   bpf_trampoline_6442524138+0x7d/0x1000
   __napi_poll+0x5/0x1b0
   net_rx_action+0x342/0x740
   handle_softirqs+0xcf/0x2b0
   irq_exit_rcu+0x6c/0x90
   sysvec_apic_timer_interrupt+0x72/0x90
   </IRQ>

[mfleming@cloudflare.com: update comment]
  Link: https://lkml.kernel.org/r/20241015125158.3597702-1-matt@readmodwrite.com
Link: https://lkml.kernel.org/r/20241011120737.3300370-1-matt@readmodwrite.com
Link: https://lore.kernel.org/all/CAGis_TWzSu=P7QJmjD58WWiu3zjMTVKSzdOwWE8ORaGytzWJwQ@mail.gmail.com/
Fixes: 1d91df85f3 ("mm/page_alloc: handle a missing case for memalloc_nocma_{save/restore} APIs")
Signed-off-by: Matt Fleming <mfleming@cloudflare.com>
Suggested-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
History 2024-11-08 16:25:55 +01:00
arch riscv: Remove duplicated GET_RM 2024-11-08 16:25:55 +01:00
block block, bfq: fix procress reference leakage for bfqq in merge chain 2024-11-01 01:52:35 +01:00
certs certs/blacklist_hashes.c: fix const confusion in certs blacklist 2022-06-22 14:22:01 +02:00
crypto crypto: xor - fix template benchmarking 2024-10-17 15:10:42 +02:00
Documentation arm64: errata: Expand speculative SSBS workaround once more 2024-10-17 15:11:45 +02:00
drivers iio: light: veml6030: fix microlux value calculation 2024-11-08 16:25:54 +01:00
fs nilfs2: fix potential deadlock with newly created symlinks 2024-11-08 16:25:54 +01:00
include mm/page_alloc: fix tracepoint mm_page_alloc_zone_locked() 2024-11-08 16:25:55 +01:00
init init/main.c: Fix potential static_command_line memory overflow 2024-04-27 17:05:28 +02:00
io_uring io_uring/sqpoll: close race on waiting for sqring entries 2024-10-22 15:40:43 +02:00
ipc ipc/sem: Fix dangling sem_array access in semtimedop race 2022-12-08 11:28:45 +01:00
kernel bpf: Fix out-of-bounds write in trie_get_next_key() 2024-11-08 16:25:53 +01:00
lib lib/buildid: harden build ID parsing logic 2024-10-17 15:11:45 +02:00
LICENSES LICENSES/dual/CC-BY-4.0: Git rid of "smart quotes" 2021-07-15 06:31:24 -06:00
mm mm/page_alloc: let GFP_ATOMIC order-0 allocs access highatomic reserves 2024-11-08 16:25:55 +01:00
net wifi: mac80211: do not pass a stopped vif to the driver in .get_txpower 2024-11-08 16:25:54 +01:00
samples Add gitignore file for samples/fanotify/ subdirectory 2024-07-27 10:46:16 +02:00
scripts kconfig: qconf: fix buffer overflow in debug links 2024-10-17 15:11:43 +02:00
security selinux: improve error checking in sel_write_load() 2024-11-01 01:52:38 +01:00
sound ASoC: cs42l51: Fix some error handling paths in cs42l51_probe() 2024-11-08 16:25:52 +01:00
tools usbip: tools: Fix detach_port() invalid port error path 2024-11-08 16:25:54 +01:00
usr usr/include/Makefile: add linux/nfc.h to the compile-test coverage 2022-02-01 17:27:15 +01:00
virt KVM: Fix a data race on last_boosted_vcpu in kvm_vcpu_on_spin() 2024-10-22 15:40:41 +02:00
.clang-format clang-format: Update with the latest for_each macro list 2021-05-12 23:32:39 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore Remove *.orig pattern from .gitignore 2024-10-17 15:11:10 +02:00
.mailmap mailmap: add Andrej Shadura 2021-10-18 20:22:03 -10:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Move Daniel Drake to credits 2021-09-21 08:34:58 +03:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS trace: Relocate event helper files 2024-04-10 16:19:24 +02:00
Makefile Linux 5.15.170 2024-11-01 01:52:38 +01:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

README 

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.