syzbot

capability: warning: `syz.6.683' uses deprecated v2 capabilities in a way that may be insecure
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.6.683/9371 is trying to acquire lock:
ffff88807d924ae8 (&sdp->sd_quota_mutex){+.+.}-{3:3}, at: do_qc+0xaf/0x670 fs/gfs2/quota.c:689

but task is already holding lock:
ffff8880550e8ca0 (&ip->i_rw_mutex){++++}-{3:3}, at: __gfs2_iomap_alloc+0x290/0x1aa0 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+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
       gfs2_quota_lock+0xba/0x7b0 fs/gfs2/quota.c:1070
       gfs2_quota_lock_check fs/gfs2/quota.h:50 [inline]
       alloc_dinode+0x182/0x5d0 fs/gfs2/inode.c:409
       gfs2_create_inode+0xdb6/0x1540 fs/gfs2/inode.c:739
       gfs2_atomic_open+0xd2/0x220 fs/gfs2/inode.c:1315
       atomic_open fs/namei.c:3359 [inline]
       lookup_open fs/namei.c:3467 [inline]
       open_last_lookups fs/namei.c:3564 [inline]
       path_openat+0xf49/0x3230 fs/namei.c:3794
       do_filp_open+0x1f5/0x430 fs/namei.c:3824
       do_sys_openat2+0x134/0x1d0 fs/open.c:1421
       do_sys_open fs/open.c:1436 [inline]
       __do_sys_openat fs/open.c:1452 [inline]
       __se_sys_openat fs/open.c:1447 [inline]
       __x64_sys_openat+0x139/0x160 fs/open.c:1447
       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
       gfs2_alloc_blocks+0x18b6/0x2070 fs/gfs2/rgrp.c:2496
       __gfs2_iomap_alloc+0x4d5/0x1aa0 fs/gfs2/bmap.c:705
       gfs2_iomap_begin_write fs/gfs2/bmap.c:1061 [inline]
       gfs2_iomap_begin+0xae5/0x12f0 fs/gfs2/bmap.c:1126
       iomap_iter+0x6b1/0xec0 fs/iomap/iter.c:91
       iomap_file_buffered_write+0x1f6/0xd80 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.6.683/9371:
 #0: ffff88801bfb0fc8 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0x2a3/0x330 fs/file.c:1040
 #1: ffff88807c9b4418 (sb_writers#23){.+.+}-{0:0}, at: vfs_write+0x21b/0x990 fs/read_write.c:580
 #2: ffff8880550e8818 (&sb->s_type->i_mutex_key#30){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:804 [inline]
 #2: ffff8880550e8818 (&sb->s_type->i_mutex_key#30){+.+.}-{3:3}, at: gfs2_file_write_iter+0x352/0xe90 fs/gfs2/file.c:1115
 #3: ffff88807c9b4608 (sb_internal#5){.+.+}-{0:0}, at: gfs2_trans_begin+0x6f/0xe0 fs/gfs2/trans.c:118
 #4: ffff88807d925060 (&sdp->sd_log_flush_lock){++++}-{3:3}, at: __gfs2_trans_begin+0x517/0x890 fs/gfs2/trans.c:87
 #5: ffff8880550e8ca0 (&ip->i_rw_mutex){++++}-{3:3}, at: __gfs2_iomap_alloc+0x290/0x1aa0 fs/gfs2/bmap.c:679

stack backtrace:
CPU: 1 PID: 9371 Comm: syz.6.683 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
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
 gfs2_alloc_blocks+0x18b6/0x2070 fs/gfs2/rgrp.c:2496
 __gfs2_iomap_alloc+0x4d5/0x1aa0 fs/gfs2/bmap.c:705
 gfs2_iomap_begin_write fs/gfs2/bmap.c:1061 [inline]
 gfs2_iomap_begin+0xae5/0x12f0 fs/gfs2/bmap.c:1126
 iomap_iter+0x6b1/0xec0 fs/iomap/iter.c:91
 iomap_file_buffered_write+0x1f6/0xd80 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: 0033:0x7fb06bf9acb9
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:00007fb06cede028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007fb06c215fa0 RCX: 00007fb06bf9acb9
RDX: 000000000208e24b RSI: 0000200000000240 RDI: 0000000000000004
RBP: 00007fb06c008bf7 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fb06c216038 R14: 00007fb06c215fa0 R15: 00007ffcc61b9bd8
 </TASK>