The patch titled
Subject: mm: wake_up only when swapcache_wq waitqueue is active
has been added to the -mm mm-hotfixes-unstable branch. Its filename is
mm-avoid-unconditional-one-tick-sleep-when-swapcache_prepare-fails-fix.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-avoid-unconditional-one-tick-sleep-when-swapcache_prepare-fails-fix.patch
This patch will later appear in the mm-hotfixes-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Barry Song <v-songbaohua@xxxxxxxx>
Subject: mm: wake_up only when swapcache_wq waitqueue is active
Date: Tue, 8 Oct 2024 20:18:27 +0800
wake_up() will acquire spinlock even waitqueue is empty. This might
involve cache sync overhead. Let's only call wake_up() when waitqueue
is active.
Link: https://lkml.kernel.org/r/20241008130807.40833-1-21cnbao@xxxxxxxxx
Signed-off-by: Barry Song <v-songbaohua@xxxxxxxx>
Suggested-by: "Huang, Ying" <ying.huang@xxxxxxxxx>
Cc: Chris Li <chrisl@xxxxxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Kairui Song <kasong@xxxxxxxxxxx>
Cc: Kalesh Singh <kaleshsingh@xxxxxxxxxx>
Cc: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Minchan Kim <minchan@xxxxxxxxxx>
Cc: Oven Liyang <liyangouwen1@xxxxxxxx>
Cc: SeongJae Park <sj@xxxxxxxxxx>
Cc: Suren Baghdasaryan <surenb@xxxxxxxxxx>
Cc: Yosry Ahmed <yosryahmed@xxxxxxxxxx>
Cc: Yu Zhao <yuzhao@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/memory.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
--- a/mm/memory.c~mm-avoid-unconditional-one-tick-sleep-when-swapcache_prepare-fails-fix
+++ a/mm/memory.c
@@ -4616,7 +4616,8 @@ out:
/* Clear the swap cache pin for direct swapin after PTL unlock */
if (need_clear_cache) {
swapcache_clear(si, entry, nr_pages);
- wake_up(&swapcache_wq);
+ if (waitqueue_active(&swapcache_wq))
+ wake_up(&swapcache_wq);
}
if (si)
put_swap_device(si);
@@ -4634,7 +4635,8 @@ out_release:
}
if (need_clear_cache) {
swapcache_clear(si, entry, nr_pages);
- wake_up(&swapcache_wq);
+ if (waitqueue_active(&swapcache_wq))
+ wake_up(&swapcache_wq);
}
if (si)
put_swap_device(si);
_
Patches currently in -mm which might be from v-songbaohua@xxxxxxxx are
mm-avoid-unconditional-one-tick-sleep-when-swapcache_prepare-fails.patch
mm-avoid-unconditional-one-tick-sleep-when-swapcache_prepare-fails-fix.patch
