syzbot


possible deadlock in bch2_gc_mark_key

Status: upstream: reported on 2024/05/27 13:22
Subsystems: bcachefs
[Documentation on labels]
Reported-by: syzbot+050e797ad21ccc3f5d1a@syzkaller.appspotmail.com
First crash: 22d, last: 5d06h
Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [bcachefs?] possible deadlock in bch2_gc_mark_key 0 (1) 2024/05/27 13:22

Sample crash report:
bcachefs (loop4): stripes_read... done
bcachefs (loop4): snapshots_read... done
bcachefs (loop4): check_allocations...
======================================================
WARNING: possible circular locking dependency detected
6.10.0-rc3-syzkaller-00022-gcea2a26553ac #0 Not tainted
------------------------------------------------------
syz-executor.4/5836 is trying to acquire lock:
ffff88805eb00988 (&c->sb_lock){+.+.}-{3:3}, at: bch2_gc_mark_key+0xc66/0x1010 fs/bcachefs/btree_gc.c:600

but task is already holding lock:
ffff88805eb01a50 (&c->btree_root_lock){+.+.}-{3:3}, at: bch2_gc_btree fs/bcachefs/btree_gc.c:644 [inline]
ffff88805eb01a50 (&c->btree_root_lock){+.+.}-{3:3}, at: bch2_gc_btrees fs/bcachefs/btree_gc.c:697 [inline]
ffff88805eb01a50 (&c->btree_root_lock){+.+.}-{3:3}, at: bch2_check_allocations+0x2c4a/0xc9c0 fs/bcachefs/btree_gc.c:1217

which lock already depends on the new lock.


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_read_write+0x2e9/0x370 fs/bcachefs/super.c:505
       bch2_fs_read_write fs/bcachefs/super.c:520 [inline]
       bch2_fs_start+0x535/0x5b0 fs/bcachefs/super.c:1052
       bch2_fs_open+0xa8d/0xdf0 fs/bcachefs/super.c:2123
       bch2_mount+0x6c0/0x1320 fs/bcachefs/fs.c:1917
       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

-> #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+0x3c0b/0xc9c0 fs/bcachefs/btree_gc.c:1217
       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:1031
       bch2_fs_open+0xa8d/0xdf0 fs/bcachefs/super.c:2123
       bch2_mount+0x6c0/0x1320 fs/bcachefs/fs.c:1917
       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);

 *** DEADLOCK ***

4 locks held by syz-executor.4/5836:
 #0: ffff88805eb00278 (&c->state_lock){+.+.}-{3:3}, at: bch2_fs_start+0x45/0x5b0 fs/bcachefs/super.c:1001
 #1: ffff88805eb268d0 (&c->gc_lock){++++}-{3:3}, at: bch2_check_allocations+0x258/0xc9c0 fs/bcachefs/btree_gc.c:1202
 #2: ffff88805eb042d0 (&c->btree_trans_barrier){.+.+}-{0:0}, at: srcu_lock_acquire include/linux/srcu.h:116 [inline]
 #2: ffff88805eb042d0 (&c->btree_trans_barrier){.+.+}-{0:0}, at: srcu_read_lock include/linux/srcu.h:215 [inline]
 #2: ffff88805eb042d0 (&c->btree_trans_barrier){.+.+}-{0:0}, at: __bch2_trans_get+0x9b0/0xdf0 fs/bcachefs/btree_iter.c:3204
 #3: ffff88805eb01a50 (&c->btree_root_lock){+.+.}-{3:3}, at: bch2_gc_btree fs/bcachefs/btree_gc.c:644 [inline]
 #3: ffff88805eb01a50 (&c->btree_root_lock){+.+.}-{3:3}, at: bch2_gc_btrees fs/bcachefs/btree_gc.c:697 [inline]
 #3: ffff88805eb01a50 (&c->btree_root_lock){+.+.}-{3:3}, at: bch2_check_allocations+0x2c4a/0xc9c0 fs/bcachefs/btree_gc.c:1217

stack backtrace:
CPU: 1 PID: 5836 Comm: syz-executor.4 Not tainted 6.10.0-rc3-syzkaller-00022-gcea2a26553ac #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/07/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:114
 check_noncircular+0x36a/0x4a0 kernel/locking/lockdep.c:2187
 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+0x3c0b/0xc9c0 fs/bcachefs/btree_gc.c:1217
 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:1031
 bch2_fs_open+0xa8d/0xdf0 fs/bcachefs/super.c:2123
 bch2_mount+0x6c0/0x1320 fs/bcachefs/fs.c:1917
 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
RIP: 0033:0x7f2f2907e5aa
Code: d8 64 89 02 48 c7 c0 ff ff ff ff eb a6 e8 de 09 00 00 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 49 89 ca b8 a5 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f2f29d74ef8 EFLAGS: 00000202 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007f2f29d74f80 RCX: 00007f2f2907e5aa
RDX: 0000000020011a00 RSI: 0000000020011a40 RDI: 00007f2f29d74f40
RBP: 0000000020011a00 R08: 00007f2f29d74f80 R09: 0000000001200014
R10: 0000000001200014 R11: 0000000000000202 R12: 0000000020011a40
R13: 00007f2f29d74f40 R14: 00000000000119fa R15: 0000000020000100
 </TASK>
fs has wrong nr_inodes: got 8, should be 7, shutting down
bcachefs (loop4): inconsistency detected - emergency read only at journal seq 10
bcachefs (loop4): bch2_gc_done(): error fsck_errors_not_fixed
bcachefs (loop4): bch2_check_allocations(): error fsck_errors_not_fixed
bcachefs (loop4): bch2_fs_recovery(): error fsck_errors_not_fixed
bcachefs (loop4): bch2_fs_start(): error starting filesystem fsck_errors_not_fixed
bcachefs (loop4): shutting down
bcachefs (loop4): shutdown complete

Crashes (4):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2024/06/13 06:57 upstream cea2a26553ac 2aa5052f .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root possible deadlock in bch2_gc_mark_key
2024/06/09 00:06 upstream dc772f8237f9 82c05ab8 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs possible deadlock in bch2_gc_mark_key
2024/06/02 22:48 upstream 83814698cf48 3113787f .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs possible deadlock in bch2_gc_mark_key
2024/05/26 15:10 upstream 9b62e02e6336 a10a183e .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root possible deadlock in bch2_gc_mark_key
* Struck through repros no longer work on HEAD.