diff options
| author | Ritesh Harjani (IBM) <ritesh.list@gmail.com> | 2026-03-01 21:44:26 +0530 |
|---|---|---|
| committer | Theodore Ts'o <tytso@mit.edu> | 2026-03-27 23:32:23 -0400 |
| commit | afe376d2c1fa78c8a1063a357c6971bba3f6da91 (patch) | |
| tree | f4df30b1d95851ed37a4f644e257c0d416a6670e | |
| parent | 1aec30021edd410b986c156f195f3d23959a9d11 (diff) | |
ext4: kunit: extents-test: lix percpu_counters list corruption
commit 82f80e2e3b23 ("ext4: add extent status cache support to kunit tests"),
added ext4_es_register_shrinker() in extents_kunit_init() function but
failed to add the unregister shrinker routine in extents_kunit_exit().
This could cause the following percpu_counters list corruption bug.
ok 1 split unwrit extent to 2 extents and convert 1st half writ
slab kmalloc-4k start c0000002007ff000 pointer offset 1448 size 4096
list_add corruption. next->prev should be prev (c000000004bc9e60), but was 0000000000000000. (next=c0000002007ff5a8).
------------[ cut here ]------------
kernel BUG at lib/list_debug.c:29!
cpu 0x2: Vector: 700 (Program Check) at [c000000241927a30]
pc: c000000000f26ed0: __list_add_valid_or_report+0x120/0x164
lr: c000000000f26ecc: __list_add_valid_or_report+0x11c/0x164
sp: c000000241927cd0
msr: 800000000282b033
current = 0xc000000241215200
paca = 0xc0000003fffff300 irqmask: 0x03 irq_happened: 0x09
pid = 258, comm = kunit_try_catch
kernel BUG at lib/list_debug.c:29!
enter ? for help
__percpu_counter_init_many+0x148/0x184
ext4_es_register_shrinker+0x74/0x23c
extents_kunit_init+0x100/0x308
kunit_try_run_case+0x78/0x1f8
kunit_generic_run_threadfn_adapter+0x40/0x70
kthread+0x190/0x1a0
start_kernel_thread+0x14/0x18
2:mon>
This happens because:
extents_kunit_init(test N):
ext4_es_register_shrinker(sbi)
percpu_counters_init() x 4; // this adds 4 list nodes to global percpu_counters list
list_add(&fbc->list, &percpu_counters);
shrinker_register();
extents_kunit_exit(test N):
kfree(sbi); // frees sbi w/o removing those 4 list nodes.
// So, those list node now becomes dangling pointers
extents_kunit_init(test N+1):
kzalloc_obj(ext4_sb_info) // allocator returns same page, but zeroed.
ext4_es_register_shrinker(sbi)
percpu_counters_init()
list_add(&fbc->list, &percpu_counters);
__list_add_valid(new, prev, next);
next->prev != prev // list corruption bug detected, since next->prev = NULL
Fixes: 82f80e2e3b23 ("ext4: add extent status cache support to kunit tests")
Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Reviewed-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Link: https://patch.msgid.link/5bb9041471dab8ce870c191c19cbe4df57473be8.1772381213.git.ritesh.list@gmail.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@kernel.org
| -rw-r--r-- | fs/ext4/extents-test.c | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/fs/ext4/extents-test.c b/fs/ext4/extents-test.c index 7c4690eb7dad..a6b3e6b592a5 100644 --- a/fs/ext4/extents-test.c +++ b/fs/ext4/extents-test.c @@ -142,8 +142,10 @@ static struct file_system_type ext_fs_type = { static void extents_kunit_exit(struct kunit *test) { - struct ext4_sb_info *sbi = k_ctx.k_ei->vfs_inode.i_sb->s_fs_info; + struct super_block *sb = k_ctx.k_ei->vfs_inode.i_sb; + struct ext4_sb_info *sbi = sb->s_fs_info; + ext4_es_unregister_shrinker(sbi); kfree(sbi); kfree(k_ctx.k_ei); kfree(k_ctx.k_data); |