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...

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@redhat.com 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-Ge...

Switching to synchronize_rcu_expedited fixes the problem.

Link: https://lkml.kernel.org/r/YpToHCmnx/HEcVyR@fuller.cnet Fixes: ff042f4a9b050 ("mm: lru_cache_disable: replace work queue synchronization with synchronize_rcu") Signed-off-by: Marcelo Tosatti mtosatti@redhat.com Tested-by: Stefan Wahren stefan.wahren@i2se.com Tested-by: Michael Larabel Michael@MichaelLarabel.com Cc: Sebastian Andrzej Siewior bigeasy@linutronix.de Cc: Nicolas Saenz Julienne nsaenzju@redhat.com Cc: Borislav Petkov bp@alien8.de Cc: Minchan Kim minchan@kernel.org Cc: Matthew Wilcox willy@infradead.org Cc: Mel Gorman mgorman@techsingularity.net Cc: Juri Lelli juri.lelli@redhat.com Cc: Thomas Gleixner tglx@linutronix.de Cc: Paul E. McKenney paulmck@kernel.org Cc: Phil Elwell phil@raspberrypi.com Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org ---

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@redhat.com are

mm-lru_cache_disable-use-synchronize_rcu_expedited.patch