syzbot

gfs2: fsid=syz:syz.0: first mount done, others may mount
gfs2: fsid=syz:syz.0: found 1 quota changes
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.5.460/6683 is trying to acquire lock:
ffff88807840cae0 (&sdp->sd_quota_mutex){+.+.}-{3:3}, at: do_qc+0xca/0x730 fs/gfs2/quota.c:682

but task is already holding lock:
ffff888041515688 (&ip->i_rw_mutex){++++}-{3:3}, at: sweep_bh_for_rgrps fs/gfs2/bmap.c:1512 [inline]
ffff888041515688 (&ip->i_rw_mutex){++++}-{3:3}, at: punch_hole+0x241b/0x35c0 fs/gfs2/bmap.c:1837

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
       punch_hole+0xd16/0x35c0 fs/gfs2/bmap.c:1798
       do_shrink+0x7a1/0x910 fs/gfs2/bmap.c:2018
       gfs2_setattr_size+0x150/0x810 fs/gfs2/bmap.c:2142
       gfs2_setattr+0x256/0x410 fs/gfs2/inode.c:2003
       notify_change+0xc74/0xf40 fs/attr.c:499
       do_truncate+0x197/0x220 fs/open.c:65
       handle_truncate fs/namei.c:3293 [inline]
       do_open fs/namei.c:3638 [inline]
       path_openat+0x27f2/0x2e70 fs/namei.c:3791
       do_filp_open+0x1c1/0x3c0 fs/namei.c:3818
       do_sys_openat2+0x142/0x490 fs/open.c:1320
       do_sys_open fs/open.c:1336 [inline]
       __do_sys_open fs/open.c:1344 [inline]
       __se_sys_open fs/open.c:1340 [inline]
       __x64_sys_open+0x11b/0x140 fs/open.c:1340
       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
       punch_hole+0x304c/0x35c0 fs/gfs2/bmap.c:1938
       do_shrink+0x7a1/0x910 fs/gfs2/bmap.c:2018
       gfs2_setattr_size+0x150/0x810 fs/gfs2/bmap.c:2142
       gfs2_setattr+0x256/0x410 fs/gfs2/inode.c:2003
       notify_change+0xc74/0xf40 fs/attr.c:499
       do_truncate+0x197/0x220 fs/open.c:65
       handle_truncate fs/namei.c:3293 [inline]
       do_open fs/namei.c:3638 [inline]
       path_openat+0x27f2/0x2e70 fs/namei.c:3791
       do_filp_open+0x1c1/0x3c0 fs/namei.c:3818
       do_sys_openat2+0x142/0x490 fs/open.c:1320
       do_sys_open fs/open.c:1336 [inline]
       __do_sys_open fs/open.c:1344 [inline]
       __se_sys_open fs/open.c:1340 [inline]
       __x64_sys_open+0x11b/0x140 fs/open.c:1340
       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.5.460/6683:
 #0: ffff88805781a460 (sb_writers#29){.+.+}-{0:0}, at: mnt_want_write+0x3d/0x90 fs/namespace.c:402
 #1: ffff8880415151f0 (&sb->s_type->i_mutex_key#35){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:758 [inline]
 #1: ffff8880415151f0 (&sb->s_type->i_mutex_key#35){+.+.}-{3:3}, at: do_truncate+0x183/0x220 fs/open.c:63
 #2: ffff88805781a650 (sb_internal#5){.+.+}-{0:0}, at: gfs2_trans_begin+0x6b/0xe0 fs/gfs2/trans.c:118
 #3: ffff88807840d058 (&sdp->sd_log_flush_lock){++++}-{3:3}, at: __gfs2_trans_begin+0x50d/0x880 fs/gfs2/trans.c:87
 #4: ffff888041515688 (&ip->i_rw_mutex){++++}-{3:3}, at: sweep_bh_for_rgrps fs/gfs2/bmap.c:1512 [inline]
 #4: ffff888041515688 (&ip->i_rw_mutex){++++}-{3:3}, at: punch_hole+0x241b/0x35c0 fs/gfs2/bmap.c:1837

stack backtrace:
CPU: 1 PID: 6683 Comm: syz.5.460 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
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
 punch_hole+0x304c/0x35c0 fs/gfs2/bmap.c:1938
 do_shrink+0x7a1/0x910 fs/gfs2/bmap.c:2018
 gfs2_setattr_size+0x150/0x810 fs/gfs2/bmap.c:2142
 gfs2_setattr+0x256/0x410 fs/gfs2/inode.c:2003
 notify_change+0xc74/0xf40 fs/attr.c:499
 do_truncate+0x197/0x220 fs/open.c:65
 handle_truncate fs/namei.c:3293 [inline]
 do_open fs/namei.c:3638 [inline]
 path_openat+0x27f2/0x2e70 fs/namei.c:3791
 do_filp_open+0x1c1/0x3c0 fs/namei.c:3818
 do_sys_openat2+0x142/0x490 fs/open.c:1320
 do_sys_open fs/open.c:1336 [inline]
 __do_sys_open fs/open.c:1344 [inline]
 __se_sys_open fs/open.c:1340 [inline]
 __x64_sys_open+0x11b/0x140 fs/open.c:1340
 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: 0033:0x7fb831d8f749
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:00007fb832c91038 EFLAGS: 00000246 ORIG_RAX: 0000000000000002
RAX: ffffffffffffffda RBX: 00007fb831fe5fa0 RCX: 00007fb831d8f749
RDX: 1df2a23c5997fa1f RSI: 0000000000084242 RDI: 0000200000000100
RBP: 00007fb831e13f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fb831fe6038 R14: 00007fb831fe5fa0 R15: 00007ffd2e33a808
 </TASK>