[Syz reported]
the existing dependency chain (in reverse order) is:
-> #1 (&c->btree_root_lock){+.+.}-{3:3}:
lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5754
__mutex_lock_common kernel/locking/mutex.c:608 [inline]
__mutex_lock+0x136/0xd70 kernel/locking/mutex.c:752
bch2_btree_roots_to_journal_entries+0xbb/0x980
fs/bcachefs/btree_update_interior.c:2633
bch2_fs_mark_clean+0x2cc/0x6d0 fs/bcachefs/sb-clean.c:376
bch2_fs_read_only+0x1101/0x1210 fs/bcachefs/super.c:381
__bch2_fs_stop+0x105/0x540 fs/bcachefs/super.c:615
generic_shutdown_super+0x136/0x2d0 fs/super.c:642
bch2_kill_sb+0x41/0x50 fs/bcachefs/fs.c:2037
deactivate_locked_super+0xc4/0x130 fs/super.c:473
cleanup_mnt+0x41f/0x4b0 fs/namespace.c:1267
task_work_run+0x24f/0x310 kernel/task_work.c:180
ptrace_notify+0x2d2/0x380 kernel/signal.c:2402
ptrace_report_syscall include/linux/ptrace.h:415 [inline]
ptrace_report_syscall_exit include/linux/ptrace.h:477 [inline]
syscall_exit_work+0xc6/0x190 kernel/entry/common.c:173
syscall_exit_to_user_mode_prepare kernel/entry/common.c:200 [inline]
__syscall_exit_to_user_mode_work kernel/entry/common.c:205 [inline]
syscall_exit_to_user_mode+0x273/0x370 kernel/entry/common.c:218
do_syscall_64+0x100/0x230 arch/x86/entry/common.c:89
entry_SYSCALL_64_after_hwframe+0x77/0x7f
-> #0 (&c->sb_lock){+.+.}-{3:3}:
check_prev_add kernel/locking/lockdep.c:3134 [inline]
check_prevs_add kernel/locking/lockdep.c:3253 [inline]
validate_chain+0x18e0/0x5900 kernel/locking/lockdep.c:3869
__lock_acquire+0x1346/0x1fd0 kernel/locking/lockdep.c:5137
lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5754
__mutex_lock_common kernel/locking/mutex.c:608 [inline]
__mutex_lock+0x136/0xd70 kernel/locking/mutex.c:752
bch2_gc_mark_key+0xc66/0x1010 fs/bcachefs/btree_gc.c:600
bch2_gc_btree fs/bcachefs/btree_gc.c:648 [inline]
bch2_gc_btrees fs/bcachefs/btree_gc.c:697 [inline]
bch2_check_allocations+0x3e06/0xcca0 fs/bcachefs/btree_gc.c:1224
bch2_run_recovery_pass+0xf0/0x1e0 fs/bcachefs/recovery_passes.c:182
bch2_run_recovery_passes+0x19e/0x820 fs/bcachefs/recovery_passes.c:225
bch2_fs_recovery+0x2370/0x3720 fs/bcachefs/recovery.c:807
bch2_fs_start+0x356/0x5b0 fs/bcachefs/super.c:1035
bch2_fs_open+0xa8d/0xdf0 fs/bcachefs/super.c:2127
bch2_mount+0x6b0/0x13a0 fs/bcachefs/fs.c:1919
legacy_get_tree+0xee/0x190 fs/fs_context.c:662
vfs_get_tree+0x90/0x2a0 fs/super.c:1780
do_new_mount+0x2be/0xb40 fs/namespace.c:3352
do_mount fs/namespace.c:3692 [inline]
__do_sys_mount fs/namespace.c:3898 [inline]
__se_sys_mount+0x2d9/0x3c0 fs/namespace.c:3875
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(&c->btree_root_lock);
lock(&c->sb_lock);
lock(&c->btree_root_lock);
lock(&c->sb_lock);
[Analysis]
bch2_btree_roots_to_journal_entries() does not need to hold sb_lock, so
we can remove sb_lock to avoid deadlock.
Reported-by: [email protected]
Closes: https://syzkaller.appspot.com/bug?extid=050e797ad21ccc3f5d1a
Signed-off-by: Lizhi Xu <[email protected]>
---
fs/bcachefs/sb-clean.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/fs/bcachefs/sb-clean.c b/fs/bcachefs/sb-clean.c
index 47f10ab57f40..7a75615ba745 100644
--- a/fs/bcachefs/sb-clean.c
+++ b/fs/bcachefs/sb-clean.c
@@ -373,6 +373,7 @@ void bch2_fs_mark_clean(struct bch_fs *c)
entry = sb_clean->start;
bch2_journal_super_entries_add_common(c, &entry, 0);
+ mutex_unlock(&c->sb_lock);
entry = bch2_btree_roots_to_journal_entries(c, entry, 0);
BUG_ON((void *) entry > vstruct_end(&sb_clean->field));
@@ -383,6 +384,7 @@ void bch2_fs_mark_clean(struct bch_fs *c)
* this should be in the write path, and we should be validating every
* superblock section:
*/
+ mutex_lock(&c->sb_lock);
ret = bch2_sb_clean_validate_late(c, sb_clean, WRITE);
if (ret) {
bch_err(c, "error writing marking filesystem clean: validate
error");
--
2.43.0
