+ mm-vmscan-dont-turn-on-cache_trim_mode-at-the-highest-scan-priority.patch added to mm-unstable branch

[Andrew Morton <akpm@linux-foundation.org>]

The patch titled
     Subject: mm, vmscan: don't turn on cache_trim_mode at the highest scan priority
has been added to the -mm mm-unstable branch.  Its filename is
     mm-vmscan-dont-turn-on-cache_trim_mode-at-the-highest-scan-priority.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-vmscan-dont-turn-on-cache_trim_mode-at-the-highest-scan-priority.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: Byungchul Park <byungchul@sk.com>
Subject: mm, vmscan: don't turn on cache_trim_mode at the highest scan priority
Date: Thu, 8 Feb 2024 15:18:25 +0900

With cache_trim_mode on, reclaim logic doesn't bother reclaiming anon
pages.  However, it should be more careful to turn on the mode because
it's going to prevent anon pages from being reclaimed even if there are a
huge number of anon pages that are very cold and which should be
reclaimed.  Even worse, that can lead kswapd_failures to reach
MAX_RECLAIM_RETRIES and stopping kswapd until direct reclaim eventually
works to resume kswapd.

Link: https://lkml.kernel.org/r/20240208061825.36640-1-byungchul@sk.com
Signed-off-by: Byungchul Park <byungchul@sk.com>
Cc: Yu Zhao <yuzhao@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/vmscan.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/mm/vmscan.c~mm-vmscan-dont-turn-on-cache_trim_mode-at-the-highest-scan-priority
+++ a/mm/vmscan.c
@@ -2269,7 +2269,8 @@ static void prepare_scan_control(pg_data
 	 * anonymous pages.
 	 */
 	file = lruvec_page_state(target_lruvec, NR_INACTIVE_FILE);
-	if (file >> sc->priority && !(sc->may_deactivate & DEACTIVATE_FILE))
+	if (sc->priority != 1 && file >> sc->priority &&
+	    !(sc->may_deactivate & DEACTIVATE_FILE))
 		sc->cache_trim_mode = 1;
 	else
 		sc->cache_trim_mode = 0;
_

Patches currently in -mm which might be from byungchul@sk.com are

mm-vmscan-dont-turn-on-cache_trim_mode-at-the-highest-scan-priority.patch