+ mm-damon-core-fix-new-damon_target-objects-leaks-on-damon_commit_targets.patch added to mm-hotfixes-unstable branch

+ mm-damon-core-fix-new-damon_target-objects-leaks-on-damon_commit_targets.patch added to mm-hotfixes-unstable branch

[Andrew Morton]

The patch titled
     Subject: mm/damon/core: fix new damon_target objects leaks on damon_commit_targets()
has been added to the -mm mm-hotfixes-unstable branch.  Its filename is
     mm-damon-core-fix-new-damon_target-objects-leaks-on-damon_commit_targets.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-damon-core-fix-new-damon_target-objects-leaks-on-damon_commit_targets.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@kernel.org>
Subject: mm/damon/core: fix new damon_target objects leaks on damon_commit_targets()
Date: Sun, 22 Dec 2024 15:12:21 -0800

Patch series "mm/damon/core: fix memory leaks and ignored inputs from
damon_commit_ctx()".

Due to two bugs in damon_commit_targets() and damon_commit_schemes(),
which are called from damon_commit_ctx(), some user inputs can be ignored,
and some mmeory objects can be leaked.  Fix those.

Note that only DAMON sysfs interface users are affected.  Other DAMON core
API user modules that more focused more on simple and dedicated production
usages, including DAMON_RECLAIM and DAMON_LRU_SORT are not using the buggy
function in the way, so not affected.


This patch (of 2):

When new DAMON targets are added via damon_commit_targets(), the newly
created targets are not deallocated when updating the internal data
(damon_commit_target()) is failed.  Worse yet, even if the setup is
successfully done, the new target is not linked to the context.  Hence,
the new targets are always leaked regardless of the internal data setup
failure.  Fix the leaks.

Link: https://lkml.kernel.org/r/20241222231222.85060-2-sj@kernel.org
Fixes: 9cb3d0b9dfce ("mm/damon/core: implement DAMON context commit function")
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

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

--- a/mm/damon/core.c~mm-damon-core-fix-new-damon_target-objects-leaks-on-damon_commit_targets
+++ a/mm/damon/core.c
@@ -961,8 +961,11 @@ static int damon_commit_targets(
 			return -ENOMEM;
 		err = damon_commit_target(new_target, false,
 				src_target, damon_target_has_pid(src));
-		if (err)
+		if (err) {
+			damon_destroy_target(new_target);
 			return err;
+		}
+		damon_add_target(dst, new_target);
 	}
 	return 0;
 }
_

Patches currently in -mm which might be from sj@kernel.org are

mm-damon-core-fix-new-damon_target-objects-leaks-on-damon_commit_targets.patch
mm-damon-core-fix-ignored-quota-goals-and-filters-of-newly-committed-schemes.patch
samples-add-a-skeleton-of-a-sample-damon-module-for-working-set-size-estimation.patch
samples-damon-wsse-start-and-stop-damon-as-the-user-requests.patch
samples-damon-wsse-implement-working-set-size-estimation-and-logging.patch
samples-damon-introduce-a-skeleton-of-a-smaple-damon-module-for-proactive-reclamation.patch
samples-damon-prcl-implement-schemes-setup.patch
replace-free-hugepage-folios-after-migration-fix-2.patch