The patch titled
Subject: mm/page_alloc: don't wake up 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-up-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-up-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
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------------------------------------------------------
From: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
Subject: mm/page_alloc: don't wake up kswapd from rmqueue() unless __GFP_KSWAPD_RECLAIM is specified
Date: Thu, 11 May 2023 22:47:36 +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. 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.
Link: https://lkml.kernel.org/r/6d6fb601-6100-92b9-cea3-e7ebacc7693a@xxxxxxxxxxxxxxxxxxx
Fixes: 73444bc4d8f9 ("mm, page_alloc: do not wake kswapd with zone lock held")
Signed-off-by: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Cc: Qian Cai <cai@xxxxxx>
Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
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-up-kswapd-from-rmqueue-unless-__gfp_kswapd_reclaim-is-specified
+++ a/mm/page_alloc.c
@@ -3052,7 +3052,8 @@ struct page *rmqueue(struct zone *prefer
out:
/* Separate test+clear to avoid unnecessary atomics */
- if (unlikely(test_bit(ZONE_BOOSTED_WATERMARK, &zone->flags))) {
+ if (unlikely(test_bit(ZONE_BOOSTED_WATERMARK, &zone->flags))
+ && (alloc_flags & ALLOC_KSWAPD)) {
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
mm-page_alloc-dont-wake-up-kswapd-from-rmqueue-unless-__gfp_kswapd_reclaim-is-specified.patch
