syzbot


possible deadlock in do_qc

Status: upstream: reported on 2024/04/28 01:25
Reported-by: syzbot+bdc96b32d35cce7a6064@syzkaller.appspotmail.com
First crash: 453d, last: 7h13m
Similar bugs (3)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream possible deadlock in do_qc gfs2 4 785 345d 473d 0/29 auto-obsoleted due to no activity on 2024/10/22 09:11
linux-5.15 possible deadlock in do_qc 4 570 4h39m 453d 0/3 upstream: reported on 2024/04/27 22:18
linux-6.6 possible deadlock in do_qc 4 6 4d01h 37d 0/2 upstream: reported on 2025/06/17 09:35

Sample crash report:
gfs2: fsid=syz:syz.0: first mount done, others may mount
capability: warning: `syz.1.800' uses deprecated v2 capabilities in a way that may be insecure
======================================================
WARNING: possible circular locking dependency detected
6.1.145-syzkaller #0 Not tainted
------------------------------------------------------
syz.1.800/7434 is trying to acquire lock:
ffff88807db8cae0 (&sdp->sd_quota_mutex){+.+.}-{3:3}, at: do_qc+0xca/0x730 fs/gfs2/quota.c:682

but task is already holding lock:
ffff888053de85e8 (&ip->i_rw_mutex){++++}-{3:3}, at: __gfs2_iomap_alloc+0x271/0x1a20 fs/gfs2/bmap.c:679

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&ip->i_rw_mutex){++++}-{3:3}:
       down_read+0x42/0x2d0 kernel/locking/rwsem.c:1520
       __gfs2_iomap_get+0x155/0x13e0 fs/gfs2/bmap.c:856
       gfs2_iomap_get+0xc1/0x120 fs/gfs2/bmap.c:1396
       bh_get+0x241/0x730 fs/gfs2/quota.c:385
       qdsb_get+0x21c/0x3c0 fs/gfs2/quota.c:522
       gfs2_quota_hold+0x194/0x5d0 fs/gfs2/quota.c:608
       gfs2_quota_lock+0xa0/0x7d0 fs/gfs2/quota.c:1076
       gfs2_quota_lock_check fs/gfs2/quota.h:50 [inline]
       __gfs2_fallocate+0x8c8/0x1c00 fs/gfs2/file.c:1298
       gfs2_fallocate+0x33d/0x470 fs/gfs2/file.c:1395
       vfs_fallocate+0x584/0x6f0 fs/open.c:323
       ioctl_preallocate fs/ioctl.c:290 [inline]
       file_ioctl fs/ioctl.c:-1 [inline]
       do_vfs_ioctl+0x1a9d/0x1d10 fs/ioctl.c:849
       __do_sys_ioctl fs/ioctl.c:868 [inline]
       __se_sys_ioctl+0x83/0x170 fs/ioctl.c:856
       do_syscall_x64 arch/x86/entry/common.c:51 [inline]
       do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

-> #0 (&sdp->sd_quota_mutex){+.+.}-{3:3}:
       check_prev_add kernel/locking/lockdep.c:3090 [inline]
       check_prevs_add kernel/locking/lockdep.c:3209 [inline]
       validate_chain kernel/locking/lockdep.c:3825 [inline]
       __lock_acquire+0x2cf8/0x7c50 kernel/locking/lockdep.c:5049
       lock_acquire+0x1b4/0x490 kernel/locking/lockdep.c:5662
       __mutex_lock_common kernel/locking/mutex.c:603 [inline]
       __mutex_lock+0x120/0xaf0 kernel/locking/mutex.c:747
       do_qc+0xca/0x730 fs/gfs2/quota.c:682
       gfs2_quota_change+0x2f5/0x8e0 fs/gfs2/quota.c:1295
       gfs2_alloc_blocks+0x18b3/0x2070 fs/gfs2/rgrp.c:2494
       __gfs2_iomap_alloc+0x4d1/0x1a20 fs/gfs2/bmap.c:705
       gfs2_iomap_alloc+0x14d/0x1d0 fs/gfs2/bmap.c:1409
       fallocate_chunk fs/gfs2/file.c:1192 [inline]
       __gfs2_fallocate+0xf78/0x1c00 fs/gfs2/file.c:1331
       gfs2_fallocate+0x33d/0x470 fs/gfs2/file.c:1395
       vfs_fallocate+0x584/0x6f0 fs/open.c:323
       ioctl_preallocate fs/ioctl.c:290 [inline]
       file_ioctl fs/ioctl.c:-1 [inline]
       do_vfs_ioctl+0x1a9d/0x1d10 fs/ioctl.c:849
       __do_sys_ioctl fs/ioctl.c:868 [inline]
       __se_sys_ioctl+0x83/0x170 fs/ioctl.c:856
       do_syscall_x64 arch/x86/entry/common.c:51 [inline]
       do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

other info that might help us debug this:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&ip->i_rw_mutex);
                               lock(&sdp->sd_quota_mutex);
                               lock(&ip->i_rw_mutex);
  lock(&sdp->sd_quota_mutex);

 *** DEADLOCK ***

5 locks held by syz.1.800/7434:
 #0: ffff888076de2460 (sb_writers#17){.+.+}-{0:0}, at: file_start_write include/linux/fs.h:3015 [inline]
 #0: ffff888076de2460 (sb_writers#17){.+.+}-{0:0}, at: vfs_fallocate+0x4f1/0x6f0 fs/open.c:322
 #1: ffff888053de8150 (&sb->s_type->i_mutex_key#22){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:758 [inline]
 #1: ffff888053de8150 (&sb->s_type->i_mutex_key#22){+.+.}-{3:3}, at: gfs2_fallocate+0x1ab/0x470 fs/gfs2/file.c:1374
 #2: ffff888076de2650 (sb_internal#2){.+.+}-{0:0}, at: gfs2_trans_begin+0x6b/0xe0 fs/gfs2/trans.c:118
 #3: ffff88807db8d058 (&sdp->sd_log_flush_lock){.+.+}-{3:3}, at: __gfs2_trans_begin+0x50d/0x880 fs/gfs2/trans.c:87
 #4: ffff888053de85e8 (&ip->i_rw_mutex){++++}-{3:3}, at: __gfs2_iomap_alloc+0x271/0x1a20 fs/gfs2/bmap.c:679

stack backtrace:
CPU: 0 PID: 7434 Comm: syz.1.800 Not tainted 6.1.145-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x168/0x22e lib/dump_stack.c:106
 check_noncircular+0x274/0x310 kernel/locking/lockdep.c:2170
 check_prev_add kernel/locking/lockdep.c:3090 [inline]
 check_prevs_add kernel/locking/lockdep.c:3209 [inline]
 validate_chain kernel/locking/lockdep.c:3825 [inline]
 __lock_acquire+0x2cf8/0x7c50 kernel/locking/lockdep.c:5049
 lock_acquire+0x1b4/0x490 kernel/locking/lockdep.c:5662
 __mutex_lock_common kernel/locking/mutex.c:603 [inline]
 __mutex_lock+0x120/0xaf0 kernel/locking/mutex.c:747
 do_qc+0xca/0x730 fs/gfs2/quota.c:682
 gfs2_quota_change+0x2f5/0x8e0 fs/gfs2/quota.c:1295
 gfs2_alloc_blocks+0x18b3/0x2070 fs/gfs2/rgrp.c:2494
 __gfs2_iomap_alloc+0x4d1/0x1a20 fs/gfs2/bmap.c:705
 gfs2_iomap_alloc+0x14d/0x1d0 fs/gfs2/bmap.c:1409
 fallocate_chunk fs/gfs2/file.c:1192 [inline]
 __gfs2_fallocate+0xf78/0x1c00 fs/gfs2/file.c:1331
 gfs2_fallocate+0x33d/0x470 fs/gfs2/file.c:1395
 vfs_fallocate+0x584/0x6f0 fs/open.c:323
 ioctl_preallocate fs/ioctl.c:290 [inline]
 file_ioctl fs/ioctl.c:-1 [inline]
 do_vfs_ioctl+0x1a9d/0x1d10 fs/ioctl.c:849
 __do_sys_ioctl fs/ioctl.c:868 [inline]
 __se_sys_ioctl+0x83/0x170 fs/ioctl.c:856
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fb92458e929
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fb925447038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fb9247b6160 RCX: 00007fb92458e929
RDX: 0000200000000240 RSI: 0000000040305828 RDI: 000000000000000a
RBP: 00007fb924610b39 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007fb9247b6160 R15: 00007ffc3ddb4c98
 </TASK>

Crashes (407):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/07/16 17:03 linux-6.1.y f2198ea7eb3e 124ec9cc .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan possible deadlock in do_qc
2025/07/10 15:09 linux-6.1.y 04d1ccaa9c28 956bd956 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan possible deadlock in do_qc
2025/07/04 22:35 linux-6.1.y 7e69c33e4858 d869b261 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan possible deadlock in do_qc
2025/07/02 16:22 linux-6.1.y 7e69c33e4858 bc80e4f0 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan possible deadlock in do_qc
2025/06/21 09:55 linux-6.1.y 58485ff1a74f d6cdfb8a .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan possible deadlock in do_qc
2025/06/08 03:27 linux-6.1.y 58485ff1a74f 4826c28e .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan possible deadlock in do_qc
2025/06/01 16:22 linux-6.1.y da3c5173c55f 3d2f584d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan possible deadlock in do_qc
2025/05/28 12:17 linux-6.1.y da3c5173c55f 874a1386 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan possible deadlock in do_qc
2025/05/27 17:19 linux-6.1.y da3c5173c55f 874a1386 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan possible deadlock in do_qc
2025/04/29 05:58 linux-6.1.y 535ec20c5027 aeb6ec69 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan possible deadlock in do_qc
2025/04/19 05:38 linux-6.1.y 420102835862 2a20f901 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan possible deadlock in do_qc
2025/03/30 18:37 linux-6.1.y 8e60a714ba3b d3999433 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan possible deadlock in do_qc
2025/07/24 19:30 linux-6.1.y 3594f306da12 65d60d73 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 possible deadlock in do_qc
2025/07/14 07:53 linux-6.1.y dfc486ec9cce 3cda49cf .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 possible deadlock in do_qc
2025/07/10 11:21 linux-6.1.y 04d1ccaa9c28 956bd956 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 possible deadlock in do_qc
2025/07/09 21:48 linux-6.1.y 04d1ccaa9c28 f4e5e155 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 possible deadlock in do_qc
2025/07/02 12:01 linux-6.1.y 7e69c33e4858 bc80e4f0 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 possible deadlock in do_qc
2025/06/30 01:23 linux-6.1.y 7e69c33e4858 fc9d8ee5 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 possible deadlock in do_qc
2025/06/26 13:03 linux-6.1.y 58485ff1a74f 26d77996 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 possible deadlock in do_qc
2025/06/24 08:15 linux-6.1.y 58485ff1a74f e2f27c35 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 possible deadlock in do_qc
2025/06/20 10:11 linux-6.1.y 58485ff1a74f ed3e87f7 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 possible deadlock in do_qc
2025/06/16 09:14 linux-6.1.y 58485ff1a74f 5f4b362d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 possible deadlock in do_qc
2025/06/16 08:55 linux-6.1.y 58485ff1a74f 5f4b362d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 possible deadlock in do_qc
2025/06/15 23:29 linux-6.1.y 58485ff1a74f 5f4b362d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 possible deadlock in do_qc
2025/06/15 13:34 linux-6.1.y 58485ff1a74f 5f4b362d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 possible deadlock in do_qc
2025/06/10 09:12 linux-6.1.y 58485ff1a74f 4826c28e .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 possible deadlock in do_qc
2025/06/02 05:09 linux-6.1.y da3c5173c55f 3d2f584d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 possible deadlock in do_qc
2025/05/31 18:46 linux-6.1.y da3c5173c55f 3d2f584d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 possible deadlock in do_qc
2025/05/27 15:26 linux-6.1.y da3c5173c55f 874a1386 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 possible deadlock in do_qc
2025/05/20 06:34 linux-6.1.y 325285d9fc86 b84f0537 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 possible deadlock in do_qc
2025/05/19 01:17 linux-6.1.y 325285d9fc86 f41472b0 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 possible deadlock in do_qc
2025/05/07 15:39 linux-6.1.y ac7079a42ea5 350f4ffc .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 possible deadlock in do_qc
2025/05/07 10:33 linux-6.1.y ac7079a42ea5 350f4ffc .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 possible deadlock in do_qc
2025/04/28 07:32 linux-6.1.y 535ec20c5027 c6b4fb39 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 possible deadlock in do_qc
2025/04/27 01:37 linux-6.1.y 535ec20c5027 c6b4fb39 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 possible deadlock in do_qc
2025/04/26 03:47 linux-6.1.y 535ec20c5027 c6b4fb39 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 possible deadlock in do_qc
2025/04/20 13:43 linux-6.1.y 420102835862 2a20f901 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 possible deadlock in do_qc
2025/04/14 21:06 linux-6.1.y 420102835862 0bd6db41 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 possible deadlock in do_qc
2025/04/13 08:47 linux-6.1.y 420102835862 0bd6db41 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 possible deadlock in do_qc
2025/04/08 17:22 linux-6.1.y 3dfebb87d7eb a775275d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 possible deadlock in do_qc
2025/04/01 11:15 linux-6.1.y 8e60a714ba3b 36d76a97 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 possible deadlock in do_qc
2025/03/30 11:11 linux-6.1.y 8e60a714ba3b d3999433 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 possible deadlock in do_qc
2025/03/30 08:19 linux-6.1.y 8e60a714ba3b d3999433 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 possible deadlock in do_qc
2025/03/22 21:58 linux-6.1.y 344a09659766 c6512ef7 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 possible deadlock in do_qc
2025/03/22 13:51 linux-6.1.y 344a09659766 c6512ef7 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 possible deadlock in do_qc
2025/03/21 17:15 linux-6.1.y 344a09659766 62330552 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 possible deadlock in do_qc
2024/04/28 01:25 linux-6.1.y f2295faba5e8 07b455f9 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 possible deadlock in do_qc
* Struck through repros no longer work on HEAD.