syzbot

======================================================
WARNING: possible circular locking dependency detected
5.15.159-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor.4/3865 is trying to acquire lock:
ffff888018f34ae0 (&sdp->sd_quota_mutex){+.+.}-{3:3}, at: do_qc+0xc8/0x720 fs/gfs2/quota.c:678

but task is already holding lock:
ffff88805d002108 (&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_fallocate+0xa7d/0x1e00 fs/gfs2/file.c:1305
       gfs2_fallocate+0x354/0x490 fs/gfs2/file.c:1402
       vfs_fallocate+0x54a/0x6b0 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+0xb9/0x100 fs/open.c:337
       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_alloc+0x155/0x1f0 fs/gfs2/bmap.c:1411
       fallocate_chunk fs/gfs2/file.c:1199 [inline]
       __gfs2_fallocate+0x1032/0x1e00 fs/gfs2/file.c:1338
       gfs2_fallocate+0x354/0x490 fs/gfs2/file.c:1402
       vfs_fallocate+0x54a/0x6b0 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+0xb9/0x100 fs/open.c:337
       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 ***

5 locks held by syz-executor.4/3865:
 #0: ffff88801a502460 (sb_writers#19){.+.+}-{0:0}, at: file_start_write include/linux/fs.h:3037 [inline]
 #0: ffff88801a502460 (sb_writers#19){.+.+}-{0:0}, at: vfs_fallocate+0x4bd/0x6b0 fs/open.c:307
 #1: ffff88805d001c70 (&sb->s_type->i_mutex_key#28){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:789 [inline]
 #1: ffff88805d001c70 (&sb->s_type->i_mutex_key#28){+.+.}-{3:3}, at: gfs2_fallocate+0x198/0x490 fs/gfs2/file.c:1381
 #2: ffff88801a502650 (sb_internal#4){.+.+}-{0:0}, at: gfs2_trans_begin+0x6d/0xe0 fs/gfs2/trans.c:118
 #3: ffff888018f350a8 (&sdp->sd_log_flush_lock){.+.+}-{3:3}, at: __gfs2_trans_begin+0x55a/0x940 fs/gfs2/trans.c:87
 #4: ffff88805d002108 (&ip->i_rw_mutex){++++}-{3:3}, at: __gfs2_iomap_alloc+0x2b7/0x2090 fs/gfs2/bmap.c:681

stack backtrace:
CPU: 1 PID: 3865 Comm: syz-executor.4 Not tainted 5.15.159-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/02/2024
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_alloc+0x155/0x1f0 fs/gfs2/bmap.c:1411
 fallocate_chunk fs/gfs2/file.c:1199 [inline]
 __gfs2_fallocate+0x1032/0x1e00 fs/gfs2/file.c:1338
 gfs2_fallocate+0x354/0x490 fs/gfs2/file.c:1402
 vfs_fallocate+0x54a/0x6b0 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+0xb9/0x100 fs/open.c:337
 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: 0033:0x7ff243610ee9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 20 00 00 90 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 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ff241b840c8 EFLAGS: 00000246 ORIG_RAX: 000000000000011d
RAX: ffffffffffffffda RBX: 00007ff24373ff80 RCX: 00007ff243610ee9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000004
RBP: 00007ff24365d49e R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000040000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000000b R14: 00007ff24373ff80 R15: 00007fff5fdb28b8
 </TASK>