Patch "mm/damon/sysfs-schemes: handle tried region directory allocation failure" has been added to the 6.6-stable tree

[<gregkh@xxxxxxxxxxxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    mm/damon/sysfs-schemes: handle tried region directory allocation failure

to the 6.6-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:
     mm-damon-sysfs-schemes-handle-tried-region-directory-allocation-failure.patch
and it can be found in the queue-6.6 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.


>From ae636ae2bbfd9279f5681dbf320d1da817e52b68 Mon Sep 17 00:00:00 2001
From: SeongJae Park <sj@xxxxxxxxxx>
Date: Mon, 6 Nov 2023 23:34:08 +0000
Subject: mm/damon/sysfs-schemes: handle tried region directory allocation failure

From: SeongJae Park <sj@xxxxxxxxxx>

commit ae636ae2bbfd9279f5681dbf320d1da817e52b68 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 mm/damon/sysfs-schemes.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/mm/damon/sysfs-schemes.c
+++ b/mm/damon/sysfs-schemes.c
@@ -1752,6 +1752,8 @@ 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 stable-queue which might be from sj@xxxxxxxxxx are

queue-6.6/mm-damon-implement-a-function-for-max-nr_accesses-safe-calculation.patch
queue-6.6/mm-damon-ops-common-avoid-divide-by-zero-during-region-hotness-calculation.patch
queue-6.6/mm-damon-sysfs-check-error-from-damon_sysfs_update_target.patch
queue-6.6/mm-damon-lru_sort-avoid-divide-by-zero-in-hot-threshold-calculation.patch
queue-6.6/mm-damon-core-avoid-divide-by-zero-during-monitoring-results-update.patch
queue-6.6/mm-damon-sysfs-schemes-handle-tried-region-directory-allocation-failure.patch
queue-6.6/mm-damon-sysfs-update-monitoring-target-regions-for-online-input-commit.patch
queue-6.6/mm-damon-sysfs-schemes-handle-tried-regions-sysfs-directory-allocation-failure.patch
queue-6.6/mm-damon-sysfs-remove-requested-targets-when-online-commit-inputs.patch
queue-6.6/mm-damon-core.c-avoid-unintentional-filtering-out-of-schemes.patch