+ mm-damon-sysfs-check-error-from-damon_sysfs_update_target.patch added to mm-hotfixes-unstable branch

+ mm-damon-sysfs-check-error-from-damon_sysfs_update_target.patch added to mm-hotfixes-unstable branch

[Andrew Morton]

The patch titled
     Subject: mm/damon/sysfs: check error from damon_sysfs_update_target()
has been added to the -mm mm-hotfixes-unstable branch.  Its filename is
     mm-damon-sysfs-check-error-from-damon_sysfs_update_target.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-check-error-from-damon_sysfs_update_target.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/sysfs: check error from damon_sysfs_update_target()
Date: Mon, 6 Nov 2023 23:34:06 +0000

Patch series "mm/damon/sysfs: fix unhandled return values".

Some of DAMON sysfs interface code is not handling return values from some
functions.  As a result, confusing user input handling or NULL-dereference
is possible.  Check those properly.


This patch (of 3):

damon_sysfs_update_target() returns error code for failures, but its
caller, damon_sysfs_set_targets() is ignoring that.  The update function
seems making no critical change in case of such failures, but the behavior
will look like DAMON sysfs is silently ignoring or only partially
accepting the user input.  Fix it.

Link: https://lkml.kernel.org/r/20231106233408.51159-1-sj@kernel.org
Link: https://lkml.kernel.org/r/20231106233408.51159-2-sj@kernel.org
Fixes: 19467a950b49 ("mm/damon/sysfs: remove requested targets when online-commit inputs")
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: <stable@vger.kernel.org>	[5.19+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/damon/sysfs.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/mm/damon/sysfs.c~mm-damon-sysfs-check-error-from-damon_sysfs_update_target
+++ a/mm/damon/sysfs.c
@@ -1203,8 +1203,10 @@ static int damon_sysfs_set_targets(struc
 
 	damon_for_each_target_safe(t, next, ctx) {
 		if (i < sysfs_targets->nr) {
-			damon_sysfs_update_target(t, ctx,
+			err = damon_sysfs_update_target(t, ctx,
 					sysfs_targets->targets_arr[i]);
+			if (err)
+				return err;
 		} else {
 			if (damon_target_has_pid(ctx))
 				put_pid(t->pid);
_

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