gfs2: fsid=syz:syz.0: first mount done, others may mount
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.1.394/6080 is trying to acquire lock:
ffff888061d88ae0 (&sdp->sd_quota_mutex){+.+.}-{3:3}, at: do_qc+0xc0/0x6c0 fs/gfs2/quota.c:678

but task is already holding lock:
ffff88802d73de10 (&ip->i_rw_mutex){++++}-{3:3}, at: __gfs2_iomap_alloc+0x28e/0x1a90 fs/gfs2/bmap.c:687

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+0x44/0x2e0 kernel/locking/rwsem.c:1498
       __gfs2_iomap_get+0x164/0x1390 fs/gfs2/bmap.c:864
       gfs2_iomap_get fs/gfs2/bmap.c:1415 [inline]
       gfs2_block_map+0x299/0x6f0 fs/gfs2/bmap.c:1230
       bh_get+0x275/0x650 fs/gfs2/quota.c:385
       qdsb_get+0x21c/0x3c0 fs/gfs2/quota.c:518
       gfs2_quota_hold+0x18d/0x5b0 fs/gfs2/quota.c:604
       gfs2_quota_lock+0xa0/0x7f0 fs/gfs2/quota.c:1076
       gfs2_quota_lock_check fs/gfs2/quota.h:50 [inline]
       alloc_dinode+0x170/0x4b0 fs/gfs2/inode.c:402
       gfs2_create_inode+0xccd/0x1460 fs/gfs2/inode.c:721
       gfs2_mkdir+0x9b/0xd0 fs/gfs2/inode.c:1238
       vfs_mkdir+0x386/0x570 fs/namei.c:4116
       do_mkdirat+0x1dd/0x5c0 fs/namei.c:4141
       __do_sys_mkdirat fs/namei.c:4156 [inline]
       __se_sys_mkdirat fs/namei.c:4154 [inline]
       __x64_sys_mkdirat+0x85/0x90 fs/namei.c:4154
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x4c/0xa0 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:3120 [inline]
       check_prevs_add kernel/locking/lockdep.c:3239 [inline]
       validate_chain kernel/locking/lockdep.c:3855 [inline]
       __lock_acquire+0x38f7/0x7d40 kernel/locking/lockdep.c:5120
       lock_acquire+0x19f/0x400 kernel/locking/lockdep.c:5737
       __mutex_lock_common+0x1e5/0x2400 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+0xc0/0x6c0 fs/gfs2/quota.c:678
       gfs2_quota_change+0x293/0x7a0 fs/gfs2/quota.c:1295
       gfs2_alloc_blocks+0x196b/0x2120 fs/gfs2/rgrp.c:2504
       __gfs2_iomap_alloc+0x4eb/0x1a90 fs/gfs2/bmap.c:713
       gfs2_iomap_alloc+0x15d/0x200 fs/gfs2/bmap.c:1428
       fallocate_chunk fs/gfs2/file.c:1200 [inline]
       __gfs2_fallocate+0xff9/0x1d40 fs/gfs2/file.c:1339
       gfs2_fallocate+0x36b/0x4b0 fs/gfs2/file.c:1403
       vfs_fallocate+0x57e/0x6f0 fs/open.c:308
       ksys_fallocate fs/open.c:331 [inline]
       __do_sys_fallocate fs/open.c:339 [inline]
       __se_sys_fallocate fs/open.c:337 [inline]
       __x64_sys_fallocate+0xbd/0x100 fs/open.c:337
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x4c/0xa0 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 ***

5 locks held by syz.1.394/6080:
 #0: ffff88801f92a460 (sb_writers#26){.+.+}-{0:0}, at: file_start_write include/linux/fs.h:3054 [inline]
 #0: ffff88801f92a460 (sb_writers#26){.+.+}-{0:0}, at: vfs_fallocate+0x4f1/0x6f0 fs/open.c:307
 #1: ffff88802d73d978 (&sb->s_type->i_mutex_key#30){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:793 [inline]
 #1: ffff88802d73d978 (&sb->s_type->i_mutex_key#30){+.+.}-{3:3}, at: gfs2_fallocate+0x1c9/0x4b0 fs/gfs2/file.c:1382
 #2: ffff88801f92a650 (sb_internal#5){.+.+}-{0:0}, at: gfs2_trans_begin+0x6b/0xe0 fs/gfs2/trans.c:118
 #3: ffff888061d890a8 (&sdp->sd_log_flush_lock){.+.+}-{3:3}, at: __gfs2_trans_begin+0x535/0x8b0 fs/gfs2/trans.c:87
 #4: ffff88802d73de10 (&ip->i_rw_mutex){++++}-{3:3}, at: __gfs2_iomap_alloc+0x28e/0x1a90 fs/gfs2/bmap.c:687

stack backtrace:
CPU: 1 PID: 6080 Comm: syz.1.394 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106
 check_noncircular+0x2f8/0x400 kernel/locking/lockdep.c:2178
 check_prev_add kernel/locking/lockdep.c:3120 [inline]
 check_prevs_add kernel/locking/lockdep.c:3239 [inline]
 validate_chain kernel/locking/lockdep.c:3855 [inline]
 __lock_acquire+0x38f7/0x7d40 kernel/locking/lockdep.c:5120
 lock_acquire+0x19f/0x400 kernel/locking/lockdep.c:5737
 __mutex_lock_common+0x1e5/0x2400 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+0xc0/0x6c0 fs/gfs2/quota.c:678
 gfs2_quota_change+0x293/0x7a0 fs/gfs2/quota.c:1295
 gfs2_alloc_blocks+0x196b/0x2120 fs/gfs2/rgrp.c:2504
 __gfs2_iomap_alloc+0x4eb/0x1a90 fs/gfs2/bmap.c:713
 gfs2_iomap_alloc+0x15d/0x200 fs/gfs2/bmap.c:1428
 fallocate_chunk fs/gfs2/file.c:1200 [inline]
 __gfs2_fallocate+0xff9/0x1d40 fs/gfs2/file.c:1339
 gfs2_fallocate+0x36b/0x4b0 fs/gfs2/file.c:1403
 vfs_fallocate+0x57e/0x6f0 fs/open.c:308
 ksys_fallocate fs/open.c:331 [inline]
 __do_sys_fallocate fs/open.c:339 [inline]
 __se_sys_fallocate fs/open.c:337 [inline]
 __x64_sys_fallocate+0xbd/0x100 fs/open.c:337
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f1708c7f2d9
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:00007f1706ed7028 EFLAGS: 00000246 ORIG_RAX: 000000000000011d
RAX: ffffffffffffffda RBX: 00007f1708f06fa0 RCX: 00007f1708c7f2d9
RDX: 0000000000fea000 RSI: 0000000000000000 RDI: 0000000000000005
RBP: 00007f1708d16888 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000002000402 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f1708f07038 R14: 00007f1708f06fa0 R15: 00007fff1ceb16d8
 </TASK>