+ mm-compaction-drop-redundant-watermark-check-in-compaction_zonelist_suitable.patch added to mm-unstable branch

+ mm-compaction-drop-redundant-watermark-check-in-compaction_zonelist_suitable.patch added to mm-unstable branch

[Andrew Morton]

The patch titled
     Subject: mm: compaction: drop redundant watermark check in compaction_zonelist_suitable()
has been added to the -mm mm-unstable branch.  Its filename is
     mm-compaction-drop-redundant-watermark-check-in-compaction_zonelist_suitable.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-compaction-drop-redundant-watermark-check-in-compaction_zonelist_suitable.patch

This patch will later appear in the mm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Before you just go and hit "reply", please:
   a) Consider who else should be cc'ed
   b) Prefer to cc a suitable mailing list as well
   c) Ideally: find the original patch on the mailing list and do a
      reply-to-all to that, adding suitable additional cc's

*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***

The -mm tree is included into linux-next via the mm-everything
branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there every 2-3 working days

------------------------------------------------------
From: Johannes Weiner <hannes@cmpxchg.org>
Subject: mm: compaction: drop redundant watermark check in compaction_zonelist_suitable()
Date: Fri, 19 May 2023 14:39:59 +0200

The watermark check in compaction_zonelist_suitable(), called from
should_compact_retry(), is sandwiched between two watermark checks
already: before, there are freelist attempts as part of direct reclaim and
direct compaction; after, there is a last-minute freelist attempt in
__alloc_pages_may_oom().

The check in compaction_zonelist_suitable() isn't necessary. Kill it.

Link: https://lkml.kernel.org/r/20230519123959.77335-6-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/compaction.c |    7 -------
 1 file changed, 7 deletions(-)

--- a/mm/compaction.c~mm-compaction-drop-redundant-watermark-check-in-compaction_zonelist_suitable
+++ a/mm/compaction.c
@@ -2301,13 +2301,6 @@ bool compaction_zonelist_suitable(struct
 	for_each_zone_zonelist_nodemask(zone, z, ac->zonelist,
 				ac->highest_zoneidx, ac->nodemask) {
 		unsigned long available;
-		unsigned long watermark;
-
-		/* Allocation can already succeed, nothing to do */
-		watermark = wmark_pages(zone, alloc_flags & ALLOC_WMARK_MASK);
-		if (zone_watermark_ok(zone, order, watermark,
-				      ac->highest_zoneidx, alloc_flags))
-			continue;
 
 		/*
 		 * Do not consider all the reclaimable memory because we do not
_

Patches currently in -mm which might be from hannes@cmpxchg.org are

mm-compaction-remove-compaction-result-helpers.patch
mm-compaction-simplify-should_compact_retry.patch
mm-compaction-refactor-__compaction_suitable.patch
mm-compaction-remove-unnecessary-is_via_compact_memory-checks.patch
mm-compaction-drop-redundant-watermark-check-in-compaction_zonelist_suitable.patch