syzbot

======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.2.86/4794 is trying to acquire lock:
ffff88807b578ae0 (&sdp->sd_quota_mutex){+.+.}-{3:3}, at: do_qc+0xca/0x730 fs/gfs2/quota.c:682

but task is already holding lock:
ffff88805a234fd0 (&ip->i_rw_mutex){++++}-{3:3}, at: sweep_bh_for_rgrps fs/gfs2/bmap.c:1512 [inline]
ffff88805a234fd0 (&ip->i_rw_mutex){++++}-{3:3}, at: punch_hole+0x24b8/0x3760 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+0x15b/0x1400 fs/gfs2/bmap.c:856
       gfs2_iomap_get+0xeb/0x170 fs/gfs2/bmap.c:1396
       bh_get+0x26d/0x780 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+0xda8/0x3760 fs/gfs2/bmap.c:1798
       do_shrink+0x7c6/0x930 fs/gfs2/bmap.c:2018
       gfs2_setattr_size+0x14d/0x860 fs/gfs2/bmap.c:2142
       gfs2_setattr+0x273/0x440 fs/gfs2/inode.c:2003
       notify_change+0xc74/0xf40 fs/attr.c:499
       do_truncate+0x1ac/0x240 fs/open.c:65
       handle_truncate fs/namei.c:3293 [inline]
       do_open fs/namei.c:3638 [inline]
       path_openat+0x2861/0x2ee0 fs/namei.c:3791
       do_filp_open+0x1f1/0x430 fs/namei.c:3818
       do_sys_openat2+0x150/0x4b0 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:46 [inline]
       do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
       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+0x2d07/0x7d10 kernel/locking/lockdep.c:5049
       lock_acquire+0x1bb/0x4a0 kernel/locking/lockdep.c:5662
       __mutex_lock_common kernel/locking/mutex.c:603 [inline]
       __mutex_lock+0x12d/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+0x3155/0x3760 fs/gfs2/bmap.c:1938
       do_shrink+0x7c6/0x930 fs/gfs2/bmap.c:2018
       gfs2_setattr_size+0x14d/0x860 fs/gfs2/bmap.c:2142
       gfs2_setattr+0x273/0x440 fs/gfs2/inode.c:2003
       notify_change+0xc74/0xf40 fs/attr.c:499
       do_truncate+0x1ac/0x240 fs/open.c:65
       handle_truncate fs/namei.c:3293 [inline]
       do_open fs/namei.c:3638 [inline]
       path_openat+0x2861/0x2ee0 fs/namei.c:3791
       do_filp_open+0x1f1/0x430 fs/namei.c:3818
       do_sys_openat2+0x150/0x4b0 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:46 [inline]
       do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
       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.2.86/4794:
 #0: ffff88801e75e460 (sb_writers#20){.+.+}-{0:0}, at: mnt_want_write+0x3d/0x90 fs/namespace.c:402
 #1: ffff88805a234b38 (&sb->s_type->i_mutex_key#27){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:758 [inline]
 #1: ffff88805a234b38 (&sb->s_type->i_mutex_key#27){+.+.}-{3:3}, at: do_truncate+0x198/0x240 fs/open.c:63
 #2: ffff88801e75e650 (sb_internal#5){.+.+}-{0:0}, at: gfs2_trans_begin+0x6b/0xe0 fs/gfs2/trans.c:118
 #3: ffff88807b579058 (&sdp->sd_log_flush_lock){.+.+}-{3:3}, at: __gfs2_trans_begin+0x513/0x890 fs/gfs2/trans.c:87
 #4: ffff88805a234fd0 (&ip->i_rw_mutex){++++}-{3:3}, at: sweep_bh_for_rgrps fs/gfs2/bmap.c:1512 [inline]
 #4: ffff88805a234fd0 (&ip->i_rw_mutex){++++}-{3:3}, at: punch_hole+0x24b8/0x3760 fs/gfs2/bmap.c:1837

stack backtrace:
CPU: 0 PID: 4794 Comm: syz.2.86 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x188/0x24e lib/dump_stack.c:106
 check_noncircular+0x296/0x330 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+0x2d07/0x7d10 kernel/locking/lockdep.c:5049
 lock_acquire+0x1bb/0x4a0 kernel/locking/lockdep.c:5662
 __mutex_lock_common kernel/locking/mutex.c:603 [inline]
 __mutex_lock+0x12d/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+0x3155/0x3760 fs/gfs2/bmap.c:1938
 do_shrink+0x7c6/0x930 fs/gfs2/bmap.c:2018
 gfs2_setattr_size+0x14d/0x860 fs/gfs2/bmap.c:2142
 gfs2_setattr+0x273/0x440 fs/gfs2/inode.c:2003
 notify_change+0xc74/0xf40 fs/attr.c:499
 do_truncate+0x1ac/0x240 fs/open.c:65
 handle_truncate fs/namei.c:3293 [inline]
 do_open fs/namei.c:3638 [inline]
 path_openat+0x2861/0x2ee0 fs/namei.c:3791
 do_filp_open+0x1f1/0x430 fs/namei.c:3818
 do_sys_openat2+0x150/0x4b0 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:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f15d379aeb9
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f15d46f2028 EFLAGS: 00000246 ORIG_RAX: 0000000000000002
RAX: ffffffffffffffda RBX: 00007f15d3a16090 RCX: 00007f15d379aeb9
RDX: 0000000000000006 RSI: 000000000014927e RDI: 00002000000000c0
RBP: 00007f15d3808c1f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f15d3a16128 R14: 00007f15d3a16090 R15: 00007fff0f9e5b38
 </TASK>