syzbot

======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.0.35/6043 is trying to acquire lock:
ffff888026214ae8 (&sdp->sd_quota_mutex){+.+.}-{3:3}, at: do_qc+0xaf/0x670 fs/gfs2/quota.c:689

but task is already holding lock:
ffff88805ebacfd0 (&ip->i_rw_mutex){++++}-{3:3}, at: sweep_bh_for_rgrps fs/gfs2/bmap.c:1526 [inline]
ffff88805ebacfd0 (&ip->i_rw_mutex){++++}-{3:3}, at: punch_hole+0x1c7d/0x2d70 fs/gfs2/bmap.c:1850

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+0x46/0x2e0 kernel/locking/rwsem.c:1520
       __gfs2_iomap_get+0x159/0x13f0 fs/gfs2/bmap.c:856
       gfs2_iomap_get+0xc5/0x120 fs/gfs2/bmap.c:1410
       bh_get+0x225/0x710 fs/gfs2/quota.c:401
       qdsb_get+0x210/0x330 fs/gfs2/quota.c:535
       gfs2_quota_hold+0x198/0x5e0 fs/gfs2/quota.c:615
       punch_hole+0x974/0x2d70 fs/gfs2/bmap.c:1811
       do_shrink fs/gfs2/bmap.c:2031 [inline]
       gfs2_setattr_size+0xc0b/0xfc0 fs/gfs2/bmap.c:2147
       gfs2_setattr+0x244/0x3f0 fs/gfs2/inode.c:2025
       notify_change+0xb0d/0xe10 fs/attr.c:499
       do_truncate+0x19b/0x220 fs/open.c:66
       handle_truncate fs/namei.c:3291 [inline]
       do_open fs/namei.c:3636 [inline]
       path_openat+0x298c/0x3190 fs/namei.c:3789
       do_filp_open+0x1c5/0x3d0 fs/namei.c:3816
       do_sys_openat2+0x12c/0x1c0 fs/open.c:1419
       do_sys_open fs/open.c:1434 [inline]
       __do_sys_openat fs/open.c:1450 [inline]
       __se_sys_openat fs/open.c:1445 [inline]
       __x64_sys_openat+0x139/0x160 fs/open.c:1445
       do_syscall_x64 arch/x86/entry/common.c:51 [inline]
       do_syscall_64+0x55/0xb0 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:3134 [inline]
       check_prevs_add kernel/locking/lockdep.c:3253 [inline]
       validate_chain kernel/locking/lockdep.c:3869 [inline]
       __lock_acquire+0x2ddb/0x7c80 kernel/locking/lockdep.c:5137
       lock_acquire+0x197/0x410 kernel/locking/lockdep.c:5754
       __mutex_lock_common kernel/locking/mutex.c:603 [inline]
       __mutex_lock+0x129/0xcc0 kernel/locking/mutex.c:747
       do_qc+0xaf/0x670 fs/gfs2/quota.c:689
       gfs2_quota_change+0x2b9/0x800 fs/gfs2/quota.c:1289
       punch_hole+0x280c/0x2d70 fs/gfs2/bmap.c:1951
       do_shrink fs/gfs2/bmap.c:2031 [inline]
       gfs2_setattr_size+0xc0b/0xfc0 fs/gfs2/bmap.c:2147
       gfs2_setattr+0x244/0x3f0 fs/gfs2/inode.c:2025
       notify_change+0xb0d/0xe10 fs/attr.c:499
       do_truncate+0x19b/0x220 fs/open.c:66
       handle_truncate fs/namei.c:3291 [inline]
       do_open fs/namei.c:3636 [inline]
       path_openat+0x298c/0x3190 fs/namei.c:3789
       do_filp_open+0x1c5/0x3d0 fs/namei.c:3816
       do_sys_openat2+0x12c/0x1c0 fs/open.c:1419
       do_sys_open fs/open.c:1434 [inline]
       __do_sys_openat fs/open.c:1450 [inline]
       __se_sys_openat fs/open.c:1445 [inline]
       __x64_sys_openat+0x139/0x160 fs/open.c:1445
       do_syscall_x64 arch/x86/entry/common.c:51 [inline]
       do_syscall_64+0x55/0xb0 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.0.35/6043:
 #0: ffff888030c46418 (sb_writers#15){.+.+}-{0:0}, at: mnt_want_write+0x41/0x90 fs/namespace.c:403
 #1: ffff88805ebacb48 (&sb->s_type->i_mutex_key#22){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:804 [inline]
 #1: ffff88805ebacb48 (&sb->s_type->i_mutex_key#22){+.+.}-{3:3}, at: do_truncate+0x187/0x220 fs/open.c:64
 #2: ffff888030c46608 (sb_internal#3){.+.+}-{0:0}, at: gfs2_trans_begin+0x6f/0xe0 fs/gfs2/trans.c:118
 #3: ffff888026215060 (&sdp->sd_log_flush_lock){++++}-{3:3}, at: __gfs2_trans_begin+0x511/0x880 fs/gfs2/trans.c:87
 #4: ffff88805ebacfd0 (&ip->i_rw_mutex){++++}-{3:3}, at: sweep_bh_for_rgrps fs/gfs2/bmap.c:1526 [inline]
 #4: ffff88805ebacfd0 (&ip->i_rw_mutex){++++}-{3:3}, at: punch_hole+0x1c7d/0x2d70 fs/gfs2/bmap.c:1850

stack backtrace:
CPU: 1 PID: 6043 Comm: syz.0.35 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x16c/0x230 lib/dump_stack.c:106
 check_noncircular+0x2bd/0x3c0 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 kernel/locking/lockdep.c:3869 [inline]
 __lock_acquire+0x2ddb/0x7c80 kernel/locking/lockdep.c:5137
 lock_acquire+0x197/0x410 kernel/locking/lockdep.c:5754
 __mutex_lock_common kernel/locking/mutex.c:603 [inline]
 __mutex_lock+0x129/0xcc0 kernel/locking/mutex.c:747
 do_qc+0xaf/0x670 fs/gfs2/quota.c:689
 gfs2_quota_change+0x2b9/0x800 fs/gfs2/quota.c:1289
 punch_hole+0x280c/0x2d70 fs/gfs2/bmap.c:1951
 do_shrink fs/gfs2/bmap.c:2031 [inline]
 gfs2_setattr_size+0xc0b/0xfc0 fs/gfs2/bmap.c:2147
 gfs2_setattr+0x244/0x3f0 fs/gfs2/inode.c:2025
 notify_change+0xb0d/0xe10 fs/attr.c:499
 do_truncate+0x19b/0x220 fs/open.c:66
 handle_truncate fs/namei.c:3291 [inline]
 do_open fs/namei.c:3636 [inline]
 path_openat+0x298c/0x3190 fs/namei.c:3789
 do_filp_open+0x1c5/0x3d0 fs/namei.c:3816
 do_sys_openat2+0x12c/0x1c0 fs/open.c:1419
 do_sys_open fs/open.c:1434 [inline]
 __do_sys_openat fs/open.c:1450 [inline]
 __se_sys_openat fs/open.c:1445 [inline]
 __x64_sys_openat+0x139/0x160 fs/open.c:1445
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fecc2b8eba9
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:00007fecc39ac038 EFLAGS: 00000246
 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007fecc2dd6090 RCX: 00007fecc2b8eba9
RDX: 0000000000000700 RSI: 0000200000000100 RDI: ffffffffffffff9c
RBP: 00007fecc2c11e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fecc2dd6128 R14: 00007fecc2dd6090 R15: 00007ffc4f51d138
 </TASK>