The patch titled
Subject: mm: vmscan: hold write lock to reparent shrinker nr_deferred
has been added to the -mm mm-unstable branch. Its filename is
mm-vmscan-hold-write-lock-to-reparent-shrinker-nr_deferred.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-vmscan-hold-write-lock-to-reparent-shrinker-nr_deferred.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: Qi Zheng <zhengqi.arch@xxxxxxxxxxxxx>
Subject: mm: vmscan: hold write lock to reparent shrinker nr_deferred
Date: Mon, 13 Mar 2023 19:28:17 +0800
For now, reparent_shrinker_deferred() is the only holder of read lock of
shrinker_rwsem. And it already holds the global cgroup_mutex, so it will
not be called in parallel.
Therefore, in order to convert shrinker_rwsem to shrinker_mutex later,
here we change to hold the write lock of shrinker_rwsem to reparent.
Link: https://lkml.kernel.org/r/20230313112819.38938-7-zhengqi.arch@xxxxxxxxxxxxx
Signed-off-by: Qi Zheng <zhengqi.arch@xxxxxxxxxxxxx>
Acked-by: Vlastimil Babka <vbabka@xxxxxxx>
Acked-by: Kirill Tkhai <tkhai@xxxxx>
Cc: Christian König <christian.koenig@xxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: Davidlohr Bueso <dave@xxxxxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxxxx>
Cc: Muchun Song <muchun.song@xxxxxxxxx>
Cc: Paul E. McKenney <paulmck@xxxxxxxxxx>
Cc: Roman Gushchin <roman.gushchin@xxxxxxxxx>
Cc: Shakeel Butt <shakeelb@xxxxxxxxxx>
Cc: Sultan Alsawaf <sultan@xxxxxxxxxxxxxxx>
Cc: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
Cc: Yang Shi <shy828301@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
--- a/mm/vmscan.c~mm-vmscan-hold-write-lock-to-reparent-shrinker-nr_deferred
+++ a/mm/vmscan.c
@@ -445,7 +445,7 @@ void reparent_shrinker_deferred(struct m
parent = root_mem_cgroup;
/* Prevent from concurrent shrinker_info expand */
- down_read(&shrinker_rwsem);
+ down_write(&shrinker_rwsem);
for_each_node(nid) {
child_info = shrinker_info_protected(memcg, nid);
parent_info = shrinker_info_protected(parent, nid);
@@ -454,7 +454,7 @@ void reparent_shrinker_deferred(struct m
atomic_long_add(nr, &parent_info->nr_deferred[i]);
}
}
- up_read(&shrinker_rwsem);
+ up_write(&shrinker_rwsem);
}
static bool cgroup_reclaim(struct scan_control *sc)
_
Patches currently in -mm which might be from zhengqi.arch@xxxxxxxxxxxxx are
mm-vmscan-add-a-map_nr_max-field-to-shrinker_info.patch
mm-vmscan-make-global-slab-shrink-lockless.patch
mm-vmscan-make-memcg-slab-shrink-lockless.patch
mm-shrinkers-make-count-and-scan-in-shrinker-debugfs-lockless.patch
mm-vmscan-hold-write-lock-to-reparent-shrinker-nr_deferred.patch
mm-vmscan-remove-shrinker_rwsem-from-synchronize_shrinkers.patch
mm-shrinkers-convert-shrinker_rwsem-to-mutex.patch
