syzbot

======================================================
WARNING: possible circular locking dependency detected
5.15.173-syzkaller #0 Not tainted
------------------------------------------------------
syz.4.62/4568 is trying to acquire lock:
ffff88807e7acae0 (&sdp->sd_quota_mutex){+.+.}-{3:3}, at: do_qc+0xc8/0x720 fs/gfs2/quota.c:678

but task is already holding lock:
ffff888062513c28 (&ip->i_rw_mutex){++++}-{3:3}, at: __gfs2_iomap_alloc+0x2b7/0x2090 fs/gfs2/bmap.c:681

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&ip->i_rw_mutex){++++}-{3:3}:
       lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5623
       down_read+0x45/0x2e0 kernel/locking/rwsem.c:1498
       __gfs2_iomap_get+0x178/0x1480 fs/gfs2/bmap.c:858
       gfs2_iomap_get fs/gfs2/bmap.c:1398 [inline]
       gfs2_block_map+0x292/0x830 fs/gfs2/bmap.c:1213
       bh_get+0x26d/0x6a0 fs/gfs2/quota.c:385
       qdsb_get+0x209/0x3b0 fs/gfs2/quota.c:518
       gfs2_quota_hold+0x19d/0x5c0 fs/gfs2/quota.c:604
       gfs2_quota_lock+0x9f/0x450 fs/gfs2/quota.c:1076
       gfs2_quota_lock_check fs/gfs2/quota.h:50 [inline]
       gfs2_iomap_begin_write fs/gfs2/bmap.c:1015 [inline]
       gfs2_iomap_begin+0x722/0x1350 fs/gfs2/bmap.c:1114
       iomap_iter+0x631/0xe30 fs/iomap/iter.c:74
       iomap_file_buffered_write+0x248/0x8a0 fs/iomap/buffered-io.c:814
       gfs2_file_buffered_write+0x3e3/0x850 fs/gfs2/file.c:1057
       gfs2_file_write_iter+0x4a2/0xf10 fs/gfs2/file.c:1165
       call_write_iter include/linux/fs.h:2174 [inline]
       new_sync_write fs/read_write.c:507 [inline]
       vfs_write+0xacd/0xe50 fs/read_write.c:594
       ksys_write+0x1a2/0x2c0 fs/read_write.c:647
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x66/0xd0

-> #0 (&sdp->sd_quota_mutex){+.+.}-{3:3}:
       check_prev_add kernel/locking/lockdep.c:3053 [inline]
       check_prevs_add kernel/locking/lockdep.c:3172 [inline]
       validate_chain+0x1649/0x5930 kernel/locking/lockdep.c:3788
       __lock_acquire+0x1295/0x1ff0 kernel/locking/lockdep.c:5012
       lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5623
       __mutex_lock_common+0x1da/0x25a0 kernel/locking/mutex.c:596
       __mutex_lock kernel/locking/mutex.c:729 [inline]
       mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
       do_qc+0xc8/0x720 fs/gfs2/quota.c:678
       gfs2_quota_change+0x2db/0x8c0 fs/gfs2/quota.c:1295
       gfs2_alloc_blocks+0x1f0a/0x2970 fs/gfs2/rgrp.c:2504
       __gfs2_iomap_alloc+0x4f0/0x2090 fs/gfs2/bmap.c:707
       gfs2_iomap_begin_write fs/gfs2/bmap.c:1049 [inline]
       gfs2_iomap_begin+0xb12/0x1350 fs/gfs2/bmap.c:1114
       iomap_iter+0x631/0xe30 fs/iomap/iter.c:74
       iomap_file_buffered_write+0x248/0x8a0 fs/iomap/buffered-io.c:814
       gfs2_file_buffered_write+0x3e3/0x850 fs/gfs2/file.c:1057
       gfs2_file_write_iter+0x4a2/0xf10 fs/gfs2/file.c:1165
       call_write_iter include/linux/fs.h:2174 [inline]
       new_sync_write fs/read_write.c:507 [inline]
       vfs_write+0xacd/0xe50 fs/read_write.c:594
       ksys_write+0x1a2/0x2c0 fs/read_write.c:647
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x66/0xd0

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.4.62/4568:
 #0: ffff8880240b99f0 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0x2cb/0x380 fs/file.c:1057
 #1: ffff88807b8de460 (sb_writers#25){.+.+}-{0:0}, at: vfs_write+0x29a/0xe50 fs/read_write.c:590
 #2: ffff888062513790 (&sb->s_type->i_mutex_key#30){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:789 [inline]
 #2: ffff888062513790 (&sb->s_type->i_mutex_key#30){+.+.}-{3:3}, at: gfs2_file_write_iter+0x373/0xf10 fs/gfs2/file.c:1122
 #3: ffff88807b8de650 (sb_internal#5){.+.+}-{0:0}, at: gfs2_trans_begin+0x6d/0xe0 fs/gfs2/trans.c:118
 #4: ffff88807e7ad0a8 (&sdp->sd_log_flush_lock){.+.+}-{3:3}, at: __gfs2_trans_begin+0x55a/0x940 fs/gfs2/trans.c:87
 #5: ffff888062513c28 (&ip->i_rw_mutex){++++}-{3:3}, at: __gfs2_iomap_alloc+0x2b7/0x2090 fs/gfs2/bmap.c:681

stack backtrace:
CPU: 1 PID: 4568 Comm: syz.4.62 Not tainted 5.15.173-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e3/0x2d0 lib/dump_stack.c:106
 check_noncircular+0x2f8/0x3b0 kernel/locking/lockdep.c:2133
 check_prev_add kernel/locking/lockdep.c:3053 [inline]
 check_prevs_add kernel/locking/lockdep.c:3172 [inline]
 validate_chain+0x1649/0x5930 kernel/locking/lockdep.c:3788
 __lock_acquire+0x1295/0x1ff0 kernel/locking/lockdep.c:5012
 lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5623
 __mutex_lock_common+0x1da/0x25a0 kernel/locking/mutex.c:596
 __mutex_lock kernel/locking/mutex.c:729 [inline]
 mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
 do_qc+0xc8/0x720 fs/gfs2/quota.c:678
 gfs2_quota_change+0x2db/0x8c0 fs/gfs2/quota.c:1295
 gfs2_alloc_blocks+0x1f0a/0x2970 fs/gfs2/rgrp.c:2504
 __gfs2_iomap_alloc+0x4f0/0x2090 fs/gfs2/bmap.c:707
 gfs2_iomap_begin_write fs/gfs2/bmap.c:1049 [inline]
 gfs2_iomap_begin+0xb12/0x1350 fs/gfs2/bmap.c:1114
 iomap_iter+0x631/0xe30 fs/iomap/iter.c:74
 iomap_file_buffered_write+0x248/0x8a0 fs/iomap/buffered-io.c:814
 gfs2_file_buffered_write+0x3e3/0x850 fs/gfs2/file.c:1057
 gfs2_file_write_iter+0x4a2/0xf10 fs/gfs2/file.c:1165
 call_write_iter include/linux/fs.h:2174 [inline]
 new_sync_write fs/read_write.c:507 [inline]
 vfs_write+0xacd/0xe50 fs/read_write.c:594
 ksys_write+0x1a2/0x2c0 fs/read_write.c:647
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7effcdfeced9
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:00007effcbe63058 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007effce1b2fa0 RCX: 00007effcdfeced9
RDX: 000000000208e24b RSI: 0000000020000340 RDI: 0000000000000004
RBP: 00007effce060cc8 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007effce1b2fa0 R15: 00007ffc6cd5b728
 </TASK>