https://github.com/torvalds/linux
Revision 9282012fc0aa248b77a69f5eb802b67c5a16bb13 authored by Jaewon Kim on 25 July 2022, 09:52:12 UTC, committed by Andrew Morton on 29 July 2022, 18:33:37 UTC
There was a report that a task is waiting at the
throttle_direct_reclaim. The pgscan_direct_throttle in vmstat was
increasing.
This is a bug where zone_watermark_fast returns true even when the free
is very low. The commit f27ce0e14088 ("page_alloc: consider highatomic
reserve in watermark fast") changed the watermark fast to consider
highatomic reserve. But it did not handle a negative value case which
can be happened when reserved_highatomic pageblock is bigger than the
actual free.
If watermark is considered as ok for the negative value, allocating
contexts for order-0 will consume all free pages without direct reclaim,
and finally free page may become depleted except highatomic free.
Then allocating contexts may fall into throttle_direct_reclaim. This
symptom may easily happen in a system where wmark min is low and other
reclaimers like kswapd does not make free pages quickly.
Handle the negative case by using MIN.
Link: https://lkml.kernel.org/r/20220725095212.25388-1-jaewon31.kim@samsung.com
Fixes: f27ce0e14088 ("page_alloc: consider highatomic reserve in watermark fast")
Signed-off-by: Jaewon Kim <jaewon31.kim@samsung.com>
Reported-by: GyeongHwan Hong <gh21.hong@samsung.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Baoquan He <bhe@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Yong-Taek Lee <ytk.lee@samsung.com>
Cc: <stable@vger.kerenl.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
1 parent 1f7ea54
Tip revision: 9282012fc0aa248b77a69f5eb802b67c5a16bb13 authored by Jaewon Kim on 25 July 2022, 09:52:12 UTC
page_alloc: fix invalid watermark check on a negative value
page_alloc: fix invalid watermark check on a negative value
Tip revision: 9282012
mksysmap
#!/bin/sh -x
# Based on the vmlinux file create the System.map file
# System.map is used by module-init tools and some debugging
# tools to retrieve the actual addresses of symbols in the kernel.
#
# Usage
# mksysmap vmlinux System.map
#####
# Generate System.map (actual filename passed as second argument)
# $NM produces the following output:
# f0081e80 T alloc_vfsmnt
# The second row specify the type of the symbol:
# A = Absolute
# B = Uninitialised data (.bss)
# C = Common symbol
# D = Initialised data
# G = Initialised data for small objects
# I = Indirect reference to another symbol
# N = Debugging symbol
# R = Read only
# S = Uninitialised data for small objects
# T = Text code symbol
# U = Undefined symbol
# V = Weak symbol
# W = Weak symbol
# Corresponding small letters are local symbols
# For System.map filter away:
# a - local absolute symbols
# U - undefined global symbols
# N - debugging symbols
# w - local weak symbols
# readprofile starts reading symbols when _stext is found, and
# continue until it finds a symbol which is not either of 'T', 't',
# 'W' or 'w'. __crc_ are 'A' and placed in the middle
# so we just ignore them to let readprofile continue to work.
# (At least sparc64 has __crc_ in the middle).
$NM -n $1 | grep -v '\( [aNUw] \)\|\(__crc_\)\|\( \$[adt]\)\|\( \.L\)' > $2
Computing file changes ...
