syzbot

gfs2: fsid=syz:syz.0: first mount done, others may mount
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.4.2973/15802 is trying to acquire lock:
ffff8880764c8ae8 (&sdp->sd_quota_mutex){+.+.}-{3:3}, at: do_qc+0xaf/0x670 fs/gfs2/quota.c:689

but task is already holding lock:
ffff8880771d4fd0 (&ip->i_rw_mutex){++++}-{3:3}, at: sweep_bh_for_rgrps fs/gfs2/bmap.c:1526 [inline]
ffff8880771d4fd0 (&ip->i_rw_mutex){++++}-{3:3}, at: punch_hole+0x1d80/0x2ec0 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+0x15f/0x1400 fs/gfs2/bmap.c:856
       gfs2_iomap_get+0xef/0x170 fs/gfs2/bmap.c:1410
       bh_get+0x251/0x760 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+0xa3a/0x2ec0 fs/gfs2/bmap.c:1811
       gfs2_iomap_end+0x4f6/0x6b0 fs/gfs2/bmap.c:1171
       iomap_iter+0x21e/0xec0 fs/iomap/iter.c:79
       iomap_file_buffered_write+0xbc0/0xd80 fs/iomap/buffered-io.c:999
       gfs2_file_buffered_write+0x4bd/0x820 fs/gfs2/file.c:1060
       gfs2_file_write_iter+0x48d/0xe90 fs/gfs2/file.c:1158
       call_write_iter include/linux/fs.h:2018 [inline]
       new_sync_write fs/read_write.c:491 [inline]
       vfs_write+0x46c/0x990 fs/read_write.c:584
       ksys_write+0x150/0x260 fs/read_write.c:637
       do_syscall_x64 arch/x86/entry/common.c:46 [inline]
       do_syscall_64+0x55/0xa0 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:3134 [inline]
       check_prevs_add kernel/locking/lockdep.c:3253 [inline]
       validate_chain kernel/locking/lockdep.c:3869 [inline]
       __lock_acquire+0x2df1/0x7d40 kernel/locking/lockdep.c:5137
       lock_acquire+0x19e/0x420 kernel/locking/lockdep.c:5754
       __mutex_lock_common kernel/locking/mutex.c:603 [inline]
       __mutex_lock+0x136/0xcc0 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+0x2902/0x2ec0 fs/gfs2/bmap.c:1951
       gfs2_iomap_end+0x4f6/0x6b0 fs/gfs2/bmap.c:1171
       iomap_iter+0x21e/0xec0 fs/iomap/iter.c:79
       iomap_file_buffered_write+0xbc0/0xd80 fs/iomap/buffered-io.c:999
       gfs2_file_buffered_write+0x4bd/0x820 fs/gfs2/file.c:1060
       gfs2_file_write_iter+0x48d/0xe90 fs/gfs2/file.c:1158
       call_write_iter include/linux/fs.h:2018 [inline]
       new_sync_write fs/read_write.c:491 [inline]
       vfs_write+0x46c/0x990 fs/read_write.c:584
       ksys_write+0x150/0x260 fs/read_write.c:637
       do_syscall_x64 arch/x86/entry/common.c:46 [inline]
       do_syscall_64+0x55/0xa0 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 ***

6 locks held by syz.4.2973/15802:
 #0: ffff8880305a34c8 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0x2a3/0x330 fs/file.c:1040
 #1: ffff888031164418 (sb_writers#29){.+.+}-{0:0}, at: vfs_write+0x21b/0x990 fs/read_write.c:580
 #2: ffff8880771d4b48 (&sb->s_type->i_mutex_key#35){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:804 [inline]
 #2: ffff8880771d4b48 (&sb->s_type->i_mutex_key#35){+.+.}-{3:3}, at: gfs2_file_write_iter+0x352/0xe90 fs/gfs2/file.c:1115
 #3: ffff888031164608 (sb_internal#5){.+.+}-{0:0}, at: gfs2_trans_begin+0x6f/0xe0 fs/gfs2/trans.c:118
 #4: ffff8880764c9060 (&sdp->sd_log_flush_lock){.+.+}-{3:3}, at: __gfs2_trans_begin+0x517/0x890 fs/gfs2/trans.c:87
 #5: ffff8880771d4fd0 (&ip->i_rw_mutex){++++}-{3:3}, at: sweep_bh_for_rgrps fs/gfs2/bmap.c:1526 [inline]
 #5: ffff8880771d4fd0 (&ip->i_rw_mutex){++++}-{3:3}, at: punch_hole+0x1d80/0x2ec0 fs/gfs2/bmap.c:1850

stack backtrace:
CPU: 0 PID: 15802 Comm: syz.4.2973 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x18c/0x250 lib/dump_stack.c:106
 check_noncircular+0x2fc/0x400 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+0x2df1/0x7d40 kernel/locking/lockdep.c:5137
 lock_acquire+0x19e/0x420 kernel/locking/lockdep.c:5754
 __mutex_lock_common kernel/locking/mutex.c:603 [inline]
 __mutex_lock+0x136/0xcc0 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+0x2902/0x2ec0 fs/gfs2/bmap.c:1951
 gfs2_iomap_end+0x4f6/0x6b0 fs/gfs2/bmap.c:1171
 iomap_iter+0x21e/0xec0 fs/iomap/iter.c:79
 iomap_file_buffered_write+0xbc0/0xd80 fs/iomap/buffered-io.c:999
 gfs2_file_buffered_write+0x4bd/0x820 fs/gfs2/file.c:1060
 gfs2_file_write_iter+0x48d/0xe90 fs/gfs2/file.c:1158
 call_write_iter include/linux/fs.h:2018 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x46c/0x990 fs/read_write.c:584
 ksys_write+0x150/0x260 fs/read_write.c:637
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f9de9f9c799
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:00007f9deaf40028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f9dea215fa0 RCX: 00007f9de9f9c799
RDX: 000000000208e24b RSI: 0000200000000040 RDI: 0000000000000005
RBP: 00007f9dea032bd9 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f9dea216038 R14: 00007f9dea215fa0 R15: 00007ffd7bdca958
 </TASK>