This is a note to let you know that I've just added the patch titled
writeback, cgroup: remove extra percpu_ref_exit()
to the 5.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
writeback-cgroup-remove-extra-percpu_ref_exit.patch
and it can be found in the queue-5.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 416e0e8ab5ff41676d04dc819bd667c6ad3f7555 Mon Sep 17 00:00:00 2001
From: Greg Thelen <gthelen@xxxxxxxxxx>
Date: Sat, 20 May 2023 12:46:24 -0700
Subject: writeback, cgroup: remove extra percpu_ref_exit()
From: Greg Thelen <gthelen@xxxxxxxxxx>
5.10 stable commit 2b00b2a0e642 ("writeback, cgroup: fix null-ptr-deref
write in bdi_split_work_to_wbs") is a backport of upstream 6.3 commit
1ba1199ec574.
In the 5.10 stable commit backport percpu_ref_exit() is called twice:
first in cgwb_release_workfn() and then in cgwb_free_rcu(). The 2nd call
is benign as percpu_ref_exit() internally detects there's nothing to do.
This fixes an non-upstream issue that only applies to 5.10.y.
Fixes: 2b00b2a0e642 ("writeback, cgroup: fix null-ptr-deref write in bdi_split_work_to_wbs")
Signed-off-by: Greg Thelen <gthelen@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
mm/backing-dev.c | 1 -
1 file changed, 1 deletion(-)
--- a/mm/backing-dev.c
+++ b/mm/backing-dev.c
@@ -404,7 +404,6 @@ static void cgwb_release_workfn(struct w
blkcg_unpin_online(blkcg);
fprop_local_destroy_percpu(&wb->memcg_completions);
- percpu_ref_exit(&wb->refcnt);
wb_exit(wb);
call_rcu(&wb->rcu, cgwb_free_rcu);
}
Patches currently in stable-queue which might be from gthelen@xxxxxxxxxx are
queue-5.10/writeback-cgroup-remove-extra-percpu_ref_exit.patch
