The patch titled
Subject: mm: lru_cache_disable: use synchronize_rcu_expedited
has been added to the -mm mm-hotfixes-unstable branch. Its filename is
mm-lru_cache_disable-use-synchronize_rcu_expedited.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-lru_cache_disable-use-synchronize_rcu_expedited.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: Marcelo Tosatti <mtosatti@xxxxxxxxxx>
Subject: mm: lru_cache_disable: use synchronize_rcu_expedited
Date: Mon, 30 May 2022 12:51:56 -0300
commit ff042f4a9b050 ("mm: lru_cache_disable: replace work queue
synchronization with synchronize_rcu") replaced lru_cache_disable's usage
of work queues with synchronize_rcu.
Some users reported large performance regressions due to this commit, for
example:
https://lore.kernel.org/all/20220521234616.GO1790663@paulmck-ThinkPad-P17-Gen-1/T/
Switching to synchronize_rcu_expedited fixes the problem.
Link: https://lkml.kernel.org/r/YpToHCmnx/HEcVyR@xxxxxxxxxxx
Fixes: ff042f4a9b050 ("mm: lru_cache_disable: replace work queue synchronization with synchronize_rcu")
Signed-off-by: Marcelo Tosatti <mtosatti@xxxxxxxxxx>
Tested-by: Stefan Wahren <stefan.wahren@xxxxxxxx>
Tested-by: Michael Larabel <Michael@xxxxxxxxxxxxxxxxxx>
Cc: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
Cc: Nicolas Saenz Julienne <nsaenzju@xxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Minchan Kim <minchan@xxxxxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
Cc: Juri Lelli <juri.lelli@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Paul E. McKenney <paulmck@xxxxxxxxxx>
Cc: Phil Elwell <phil@xxxxxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/swap.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/mm/swap.c~mm-lru_cache_disable-use-synchronize_rcu_expedited
+++ a/mm/swap.c
@@ -881,7 +881,7 @@ void lru_cache_disable(void)
* lru_disable_count = 0 will have exited the critical
* section when synchronize_rcu() returns.
*/
- synchronize_rcu();
+ synchronize_rcu_expedited();
#ifdef CONFIG_SMP
__lru_add_drain_all(true);
#else
_
Patches currently in -mm which might be from mtosatti@xxxxxxxxxx are
mm-lru_cache_disable-use-synchronize_rcu_expedited.patch
