+ mm-damon-sysfs-schemes-handle-tried-region-directory-allocation-failure.patch added to mm-hotfixes-unstable branch

[Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>]

The patch titled
     Subject: mm/damon/sysfs-schemes: handle tried region directory allocation failure
has been added to the -mm mm-hotfixes-unstable branch.  Its filename is
     mm-damon-sysfs-schemes-handle-tried-region-directory-allocation-failure.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-damon-sysfs-schemes-handle-tried-region-directory-allocation-failure.patch

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: SeongJae Park <sj@xxxxxxxxxx>
Subject: mm/damon/sysfs-schemes: handle tried region directory allocation failure
Date: Mon, 6 Nov 2023 23:34:08 +0000

DAMON sysfs interface's before_damos_apply callback
(damon_sysfs_before_damos_apply()), which creates the DAMOS tried regions
for each DAMOS action applied region, is not handling the allocation
failure for the sysfs directory data.  As a result, NULL pointer
derefeence is possible.  Fix it by handling the case.

Link: https://lkml.kernel.org/r/20231106233408.51159-4-sj@xxxxxxxxxx
Fixes: f1d13cacabe1 ("mm/damon/sysfs: implement DAMOS tried regions update command")
Signed-off-by: SeongJae Park <sj@xxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>	[6.2+]
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---

 mm/damon/sysfs-schemes.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/mm/damon/sysfs-schemes.c~mm-damon-sysfs-schemes-handle-tried-region-directory-allocation-failure
+++ a/mm/damon/sysfs-schemes.c
@@ -1826,6 +1826,8 @@ static int damon_sysfs_before_damos_appl
 		return 0;
 
 	region = damon_sysfs_scheme_region_alloc(r);
+	if (!region)
+		return 0;
 	list_add_tail(&region->list, &sysfs_regions->regions_list);
 	sysfs_regions->nr_regions++;
 	if (kobject_init_and_add(&region->kobj,
_

Patches currently in -mm which might be from sj@xxxxxxxxxx are

mm-damon-sysfs-check-error-from-damon_sysfs_update_target.patch
mm-damon-sysfs-schemes-handle-tried-regions-sysfs-directory-allocation-failure.patch
mm-damon-sysfs-schemes-handle-tried-region-directory-allocation-failure.patch