The patch titled
Subject: mm/page_alloc: don't wake kswapd from rmqueue() unless __GFP_KSWAPD_RECLAIM is specified
has been added to the -mm mm-unstable branch. Its filename is
mm-page_alloc-dont-wake-kswapd-from-rmqueue-unless-__gfp_kswapd_reclaim-is-specified.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-page_alloc-dont-wake-kswapd-from-rmqueue-unless-__gfp_kswapd_reclaim-is-specified.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next via the mm-everything
branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there every 2-3 working days
------------------------------------------------------
From: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
Subject: mm/page_alloc: don't wake kswapd from rmqueue() unless __GFP_KSWAPD_RECLAIM is specified
Date: Sun, 14 May 2023 09:28:56 +0900
Commit 73444bc4d8f9 ("mm, page_alloc: do not wake kswapd with zone lock
held") moved wakeup_kswapd() from steal_suitable_fallback() to rmqueue()
using ZONE_BOOSTED_WATERMARK flag.
Only allocation contexts that include ALLOC_KSWAPD (which corresponds to
__GFP_KSWAPD_RECLAIM) should wake kswapd, for callers are supposed to
remove __GFP_KSWAPD_RECLAIM if trying to hold pgdat->kswapd_wait has a
risk of deadlock. But since zone->flags is a shared variable, a thread
doing !__GFP_KSWAPD_RECLAIM allocation request might observe this flag
being set immediately after another thread doing __GFP_KSWAPD_RECLAIM
allocation request set this flag, causing possibility of deadlock.
Link: https://lkml.kernel.org/r/c3c3dacf-dd3b-77c9-f96a-d0982b4b2a4f@xxxxxxxxxxxxxxxxxxx
Fixes: 73444bc4d8f9 ("mm, page_alloc: do not wake kswapd with zone lock held")
Signed-off-by: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
Acked-by: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
Cc: "Huang, Ying" <ying.huang@xxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/page_alloc.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
--- a/mm/page_alloc.c~mm-page_alloc-dont-wake-kswapd-from-rmqueue-unless-__gfp_kswapd_reclaim-is-specified
+++ a/mm/page_alloc.c
@@ -2863,7 +2863,8 @@ struct page *rmqueue(struct zone *prefer
out:
/* Separate test+clear to avoid unnecessary atomics */
- if (unlikely(test_bit(ZONE_BOOSTED_WATERMARK, &zone->flags))) {
+ if ((alloc_flags & ALLOC_KSWAPD) &&
+ unlikely(test_bit(ZONE_BOOSTED_WATERMARK, &zone->flags))) {
clear_bit(ZONE_BOOSTED_WATERMARK, &zone->flags);
wakeup_kswapd(zone, 0, 0, zone_idx(zone));
}
_
Patches currently in -mm which might be from penguin-kernel@xxxxxxxxxxxxxxxxxxx are
workingset-refactor-lru-refault-to-expose-refault-recency-check-fix.patch
kasankmsan-remove-__gfp_kswapd_reclaim-usage-from-kasan-kmsan.patch
mm-page_alloc-dont-wake-kswapd-from-rmqueue-unless-__gfp_kswapd_reclaim-is-specified.patch
debugobjects-turn-off-debug_objects_enabled-from-debug_objects_oom.patch
