syzbot

======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.0.52/6238 is trying to acquire lock:
ffff88802542cae8 (&sdp->sd_quota_mutex){+.+.}-{3:3}, at: do_qc+0xaf/0x670 fs/gfs2/quota.c:689

but task is already holding lock:
ffff88805748d688 (&ip->i_rw_mutex){++++}-{3:3}, at: sweep_bh_for_rgrps fs/gfs2/bmap.c:1526 [inline]
ffff88805748d688 (&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
       gfs2_dinode_dealloc fs/gfs2/super.c:1228 [inline]
       evict_unlinked_inode fs/gfs2/super.c:1439 [inline]
       gfs2_evict_inode+0xdd0/0x1220 fs/gfs2/super.c:1525
       evict+0x486/0x870 fs/inode.c:705
       do_unlinkat+0x37b/0x570 fs/namei.c:4406
       __do_sys_unlinkat fs/namei.c:4442 [inline]
       __se_sys_unlinkat fs/namei.c:4435 [inline]
       __x64_sys_unlinkat+0xd5/0xe0 fs/namei.c:4435
       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
       evict_unlinked_inode fs/gfs2/super.c:1422 [inline]
       gfs2_evict_inode+0xcc3/0x1220 fs/gfs2/super.c:1525
       evict+0x486/0x870 fs/inode.c:705
       __dentry_kill+0x431/0x650 fs/dcache.c:611
       dentry_kill+0xb8/0x290 fs/dcache.c:-1
       dput+0xfe/0x1e0 fs/dcache.c:918
       __fput+0x5e5/0x970 fs/file_table.c:392
       task_work_run+0x1ce/0x250 kernel/task_work.c:239
       exit_task_work include/linux/task_work.h:43 [inline]
       do_exit+0x90b/0x23c0 kernel/exit.c:883
       do_group_exit+0x21b/0x2d0 kernel/exit.c:1024
       get_signal+0x12fc/0x1400 kernel/signal.c:2902
       arch_do_signal_or_restart+0x9c/0x7b0 arch/x86/kernel/signal.c:310
       exit_to_user_mode_loop+0x70/0x110 kernel/entry/common.c:174
       exit_to_user_mode_prepare+0xf6/0x180 kernel/entry/common.c:210
       irqentry_exit_to_user_mode+0x9/0x40 kernel/entry/common.c:315
       exc_page_fault+0x8f/0x110 arch/x86/mm/fault.c:1524
       asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:608

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 ***

3 locks held by syz.0.52/6238:
 #0: ffff88802385e608 (sb_internal#6){.+.+}-{0:0}, at: gfs2_trans_begin+0x6f/0xe0 fs/gfs2/trans.c:118
 #1: ffff88802542d060 (&sdp->sd_log_flush_lock){.+.+}-{3:3}, at: __gfs2_trans_begin+0x511/0x880 fs/gfs2/trans.c:87
 #2: ffff88805748d688 (&ip->i_rw_mutex){++++}-{3:3}, at: sweep_bh_for_rgrps fs/gfs2/bmap.c:1526 [inline]
 #2: ffff88805748d688 (&ip->i_rw_mutex){++++}-{3:3}, at: punch_hole+0x1c7d/0x2d70 fs/gfs2/bmap.c:1850

stack backtrace:
CPU: 0 PID: 6238 Comm: syz.0.52 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
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
 evict_unlinked_inode fs/gfs2/super.c:1422 [inline]
 gfs2_evict_inode+0xcc3/0x1220 fs/gfs2/super.c:1525
 evict+0x486/0x870 fs/inode.c:705
 __dentry_kill+0x431/0x650 fs/dcache.c:611
 dentry_kill+0xb8/0x290 fs/dcache.c:-1
 dput+0xfe/0x1e0 fs/dcache.c:918
 __fput+0x5e5/0x970 fs/file_table.c:392
 task_work_run+0x1ce/0x250 kernel/task_work.c:239
 exit_task_work include/linux/task_work.h:43 [inline]
 do_exit+0x90b/0x23c0 kernel/exit.c:883
 do_group_exit+0x21b/0x2d0 kernel/exit.c:1024
 get_signal+0x12fc/0x1400 kernel/signal.c:2902
 arch_do_signal_or_restart+0x9c/0x7b0 arch/x86/kernel/signal.c:310
 exit_to_user_mode_loop+0x70/0x110 kernel/entry/common.c:174
 exit_to_user_mode_prepare+0xf6/0x180 kernel/entry/common.c:210
 irqentry_exit_to_user_mode+0x9/0x40 kernel/entry/common.c:315
 exc_page_fault+0x8f/0x110 arch/x86/mm/fault.c:1524
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:608
RIP: 0033:0x7ffa8978f751
Code: Unable to access opcode bytes at 0x7ffa8978f727.
RSP: 002b:fffffffffffffe70 EFLAGS: 00010217
RAX: 0000000000000000 RBX: 00007ffa899e6180 RCX: 00007ffa8978f749
RDX: 0000000000000000 RSI: fffffffffffffe70 RDI: 0000000000008000
RBP: 00007ffa89813f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000
R13: 00007ffa899e6218 R14: 00007ffa899e6180 R15: 00007ffcd20553b8
 </TASK>