+ mm-damon-stat-fix-memory-leak-on-damon_start-failure-in-damon_stat_start.patch added to mm-hotfixes-unstable branch

+ mm-damon-stat-fix-memory-leak-on-damon_start-failure-in-damon_stat_start.patch added to mm-hotfixes-unstable branch

[Andrew Morton]

The patch titled
     Subject: mm/damon/stat: fix memory leak on damon_start() failure in damon_stat_start()
has been added to the -mm mm-hotfixes-unstable branch.  Its filename is
     mm-damon-stat-fix-memory-leak-on-damon_start-failure-in-damon_stat_start.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-damon-stat-fix-memory-leak-on-damon_start-failure-in-damon_stat_start.patch

This patch will later appear in the mm-hotfixes-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 various
branches at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there most days

------------------------------------------------------
From: Jackie Liu <liuyun01@kylinos.cn>
Subject: mm/damon/stat: fix memory leak on damon_start() failure in damon_stat_start()
Date: Tue, 31 Mar 2026 18:15:53 +0800

Destroy the DAMON context and reset the global pointer when damon_start()
fails.  Otherwise, the context allocated by damon_stat_build_ctx() is
leaked, and the stale damon_stat_context pointer will be overwritten on
the next enable attempt, making the old allocation permanently
unreachable.

Link: https://lkml.kernel.org/r/20260331101553.88422-1-liu.yun@linux.dev
Fixes: 369c415e6073 ("mm/damon: introduce DAMON_STAT module")
Signed-off-by: Jackie Liu <liuyun01@kylinos.cn>
Reviewed-by: SeongJae Park <sj@kernel.org>
Cc: <stable@vger.kernel.org> # 6.17.x
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/damon/stat.c |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

--- a/mm/damon/stat.c~mm-damon-stat-fix-memory-leak-on-damon_start-failure-in-damon_stat_start
+++ a/mm/damon/stat.c
@@ -249,8 +249,11 @@ static int damon_stat_start(void)
 	if (!damon_stat_context)
 		return -ENOMEM;
 	err = damon_start(&damon_stat_context, 1, true);
-	if (err)
+	if (err) {
+		damon_destroy_ctx(damon_stat_context);
+		damon_stat_context = NULL;
 		return err;
+	}
 
 	damon_stat_last_refresh_jiffies = jiffies;
 	call_control.data = damon_stat_context;
_

Patches currently in -mm which might be from liuyun01@kylinos.cn are

mm-damon-stat-fix-memory-leak-on-damon_start-failure-in-damon_stat_start.patch
mm-mempolicy-fix-memory-leak-in-weighted_interleave_auto_store.patch