syzbot

XFS (loop0): Ending clean mount
XFS (loop0): Quotacheck needed: Please wait.
XFS (loop0): Quotacheck: Done.
======================================================
WARNING: possible circular locking dependency detected
6.11.0-rc4-syzkaller-00008-g6e4436539ae1 #0 Not tainted
------------------------------------------------------
syz-executor253/5095 is trying to acquire lock:
ffffffff8ea2fd60 (fs_reclaim){+.+.}-{0:0}, at: might_alloc include/linux/sched/mm.h:334 [inline]
ffffffff8ea2fd60 (fs_reclaim){+.+.}-{0:0}, at: slab_pre_alloc_hook mm/slub.c:3939 [inline]
ffffffff8ea2fd60 (fs_reclaim){+.+.}-{0:0}, at: slab_alloc_node mm/slub.c:4017 [inline]
ffffffff8ea2fd60 (fs_reclaim){+.+.}-{0:0}, at: __do_kmalloc_node mm/slub.c:4157 [inline]
ffffffff8ea2fd60 (fs_reclaim){+.+.}-{0:0}, at: __kmalloc_noprof+0xa9/0x400 mm/slub.c:4170

but task is already holding lock:
ffff88801df8d858 (&xfs_dir_ilock_class){++++}-{3:3}, at: xfs_ilock_attr_map_shared+0x8c/0xc0 fs/xfs/xfs_inode.c:84

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&xfs_dir_ilock_class){++++}-{3:3}:
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5759
       down_write_nested+0xa2/0x220 kernel/locking/rwsem.c:1695
       xfs_reclaim_inode fs/xfs/xfs_icache.c:944 [inline]
       xfs_icwalk_process_inode fs/xfs/xfs_icache.c:1630 [inline]
       xfs_icwalk_ag+0x120e/0x1ad0 fs/xfs/xfs_icache.c:1712
       xfs_icwalk fs/xfs/xfs_icache.c:1761 [inline]
       xfs_reclaim_inodes_nr+0x2d4/0x3e0 fs/xfs/xfs_icache.c:1010
       super_cache_scan+0x40f/0x4b0 fs/super.c:227
       do_shrink_slab+0x701/0x1160 mm/shrinker.c:435
       shrink_slab+0x1093/0x14d0 mm/shrinker.c:662
       shrink_one+0x43b/0x850 mm/vmscan.c:4815
       shrink_many mm/vmscan.c:4876 [inline]
       lru_gen_shrink_node mm/vmscan.c:4954 [inline]
       shrink_node+0x3799/0x3de0 mm/vmscan.c:5934
       kswapd_shrink_node mm/vmscan.c:6762 [inline]
       balance_pgdat mm/vmscan.c:6954 [inline]
       kswapd+0x1bcd/0x35a0 mm/vmscan.c:7223
       kthread+0x2f0/0x390 kernel/kthread.c:389
       ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
       ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

-> #0 (fs_reclaim){+.+.}-{0:0}:
       check_prev_add kernel/locking/lockdep.c:3133 [inline]
       check_prevs_add kernel/locking/lockdep.c:3252 [inline]
       validate_chain+0x18e0/0x5900 kernel/locking/lockdep.c:3868
       __lock_acquire+0x137a/0x2040 kernel/locking/lockdep.c:5142
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5759
       __fs_reclaim_acquire mm/page_alloc.c:3818 [inline]
       fs_reclaim_acquire+0x88/0x140 mm/page_alloc.c:3832
       might_alloc include/linux/sched/mm.h:334 [inline]
       slab_pre_alloc_hook mm/slub.c:3939 [inline]
       slab_alloc_node mm/slub.c:4017 [inline]
       __do_kmalloc_node mm/slub.c:4157 [inline]
       __kmalloc_noprof+0xa9/0x400 mm/slub.c:4170
       kmalloc_noprof include/linux/slab.h:685 [inline]
       xfs_attr_shortform_list+0x753/0x1900 fs/xfs/xfs_attr_list.c:117
       xfs_attr_list+0x1d0/0x270 fs/xfs/xfs_attr_list.c:595
       xfs_vn_listxattr+0x1d2/0x2c0 fs/xfs/xfs_xattr.c:341
       vfs_listxattr fs/xattr.c:493 [inline]
       listxattr+0x107/0x290 fs/xattr.c:841
       path_listxattr fs/xattr.c:865 [inline]
       __do_sys_listxattr fs/xattr.c:877 [inline]
       __se_sys_listxattr fs/xattr.c:874 [inline]
       __x64_sys_listxattr+0x173/0x230 fs/xattr.c:874
       do_syscall_x64 arch/x86/entry/common.c:52 [inline]
       do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

other info that might help us debug this:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  rlock(&xfs_dir_ilock_class);
                               lock(fs_reclaim);
                               lock(&xfs_dir_ilock_class);
  lock(fs_reclaim);

 *** DEADLOCK ***

1 lock held by syz-executor253/5095:
 #0: ffff88801df8d858 (&xfs_dir_ilock_class){++++}-{3:3}, at: xfs_ilock_attr_map_shared+0x8c/0xc0 fs/xfs/xfs_inode.c:84

stack backtrace:
CPU: 0 UID: 0 PID: 5095 Comm: syz-executor253 Not tainted 6.11.0-rc4-syzkaller-00008-g6e4436539ae1 #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:93 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:119
 check_noncircular+0x36a/0x4a0 kernel/locking/lockdep.c:2186
 check_prev_add kernel/locking/lockdep.c:3133 [inline]
 check_prevs_add kernel/locking/lockdep.c:3252 [inline]
 validate_chain+0x18e0/0x5900 kernel/locking/lockdep.c:3868
 __lock_acquire+0x137a/0x2040 kernel/locking/lockdep.c:5142
 lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5759
 __fs_reclaim_acquire mm/page_alloc.c:3818 [inline]
 fs_reclaim_acquire+0x88/0x140 mm/page_alloc.c:3832
 might_alloc include/linux/sched/mm.h:334 [inline]
 slab_pre_alloc_hook mm/slub.c:3939 [inline]
 slab_alloc_node mm/slub.c:4017 [inline]
 __do_kmalloc_node mm/slub.c:4157 [inline]
 __kmalloc_noprof+0xa9/0x400 mm/slub.c:4170
 kmalloc_noprof include/linux/slab.h:685 [inline]
 xfs_attr_shortform_list+0x753/0x1900 fs/xfs/xfs_attr_list.c:117
 xfs_attr_list+0x1d0/0x270 fs/xfs/xfs_attr_list.c:595
 xfs_vn_listxattr+0x1d2/0x2c0 fs/xfs/xfs_xattr.c:341
 vfs_listxattr fs/xattr.c:493 [inline]
 listxattr+0x107/0x290 fs/xattr.c:841
 path_listxattr fs/xattr.c:865 [inline]
 __do_sys_listxattr fs/xattr.c:877 [inline]
 __se_sys_listxattr fs/xattr.c:874 [inline]
 __x64_sys_listxattr+0x173/0x230 fs/xattr.c:874
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fc8d9067469
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 21 18 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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffc1803c738 EFLAGS: 00000246 ORIG_RAX: 00000000000000c2
RAX: ffffffffffffffda RBX: 0030656c69662f2e RCX: 00007fc8d9067469
RDX: 0000000000000013 RSI: 0000000020000040 RDI: 0000000020000440
RBP: 0000000000000000 R08: 00007ffc1803c770 R09: 00007ffc1803c770
R10: 00007ffc1803c770 R11: 0000000000000246 R12: 0000000000000001
R13: 0000000000000000 R14: 431bde82d7b634db R15: 00007ffc1803c790
 </TASK>