The patch titled
Subject: selftests/damon: test removed scheme sysfs dir access bug
has been added to the -mm mm-unstable branch. Its filename is
selftests-damon-test-removed-scheme-sysfs-dir-access-bug.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/selftests-damon-test-removed-scheme-sysfs-dir-access-bug.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: SeongJae Park <sj@xxxxxxxxxx>
Subject: selftests/damon: test removed scheme sysfs dir access bug
Date: Thu, 1 Dec 2022 17:08:34 +0000
A DAMON sysfs user could start DAMON with a scheme, remove the sysfs
directory for the scheme, and then ask stats or schemes tried regions
update. The related logic were not aware of the already removed directory
situation, so it was able to results in invalid memory accesses. The fix
has made with commit 8468b486612c ("mm/damon/sysfs-schemes: skip stats
update if the scheme directory is removed"), though. Add a selftest to
avoid such kind of bugs be introduced again.
Link: https://lkml.kernel.org/r/20221201170834.62823-1-sj@xxxxxxxxxx
Signed-off-by: SeongJae Park <sj@xxxxxxxxxx>
Cc: Shuah Khan <shuah@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
tools/testing/selftests/damon/Makefile | 2
tools/testing/selftests/damon/sysfs_update_removed_scheme_dir.sh | 58 ++++++++++
2 files changed, 59 insertions(+), 1 deletion(-)
--- a/tools/testing/selftests/damon/Makefile~selftests-damon-test-removed-scheme-sysfs-dir-access-bug
+++ a/tools/testing/selftests/damon/Makefile
@@ -8,7 +8,7 @@ TEST_PROGS = debugfs_attrs.sh debugfs_sc
TEST_PROGS += debugfs_empty_targets.sh debugfs_huge_count_read_write.sh
TEST_PROGS += debugfs_duplicate_context_creation.sh
TEST_PROGS += debugfs_rm_non_contexts.sh
-TEST_PROGS += sysfs.sh
+TEST_PROGS += sysfs.sh sysfs_update_removed_scheme_dir.sh
TEST_PROGS += reclaim.sh lru_sort.sh
include ../lib.mk
--- /dev/null
+++ a/tools/testing/selftests/damon/sysfs_update_removed_scheme_dir.sh
@@ -0,0 +1,58 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+
+# Kselftest framework requirement - SKIP code is 4.
+ksft_skip=4
+
+if [ $EUID -ne 0 ]
+then
+ echo "Run as root"
+ exit $ksft_skip
+fi
+
+damon_sysfs="/sys/kernel/mm/damon/admin"
+if [ ! -d "$damon_sysfs" ]
+then
+ echo "damon sysfs not found"
+ exit $ksft_skip
+fi
+
+# clear log
+dmesg -C
+
+# start DAMON with a scheme
+echo 1 > "$damon_sysfs/kdamonds/nr_kdamonds"
+echo 1 > "$damon_sysfs/kdamonds/0/contexts/nr_contexts"
+echo "vaddr" > "$damon_sysfs/kdamonds/0/contexts/0/operations"
+echo 1 > "$damon_sysfs/kdamonds/0/contexts/0/targets/nr_targets"
+echo $$ > "$damon_sysfs/kdamonds/0/contexts/0/targets/0/pid_target"
+echo 1 > "$damon_sysfs/kdamonds/0/contexts/0/schemes/nr_schemes"
+scheme_dir="$damon_sysfs/kdamonds/0/contexts/0/schemes/0"
+echo 4096000 > "$scheme_dir/access_pattern/sz/max"
+echo 20 > "$scheme_dir/access_pattern/nr_accesses/max"
+echo 1024 > "$scheme_dir/access_pattern/age/max"
+echo "on" > "$damon_sysfs/kdamonds/0/state"
+sleep 0.3
+
+# remove scheme sysfs dir
+echo 0 > "$damon_sysfs/kdamonds/0/contexts/0/schemes/nr_schemes"
+
+# try to update stat of already removed scheme sysfs dir
+echo "update_schemes_stats" > "$damon_sysfs/kdamonds/0/state"
+if dmesg | grep -q BUG
+then
+ echo "update_schemes_stats triggers a kernel bug"
+ dmesg
+ exit 1
+fi
+
+# try to update tried regions of already removed scheme sysfs dir
+echo "update_schemes_tried_regions" > "$damon_sysfs/kdamonds/0/state"
+if dmesg | grep -q BUG
+then
+ echo "update_schemes_tried_regions triggers a kernel bug"
+ dmesg
+ exit 1
+fi
+
+echo "off" > "$damon_sysfs/kdamonds/0/state"
_
Patches currently in -mm which might be from sj@xxxxxxxxxx are
selftests-damon-test-removed-scheme-sysfs-dir-access-bug.patch
