syzbot

======================================================
WARNING: possible circular locking dependency detected
6.11.0-rc3-syzkaller-00013-g6b0f8db921ab #0 Not tainted
------------------------------------------------------
kswapd0/75 is trying to acquire lock:
ffff8880118eaf98 (&xfs_nondir_ilock_class#3){++++}-{3:3}, at: xfs_reclaim_inode fs/xfs/xfs_icache.c:944 [inline]
ffff8880118eaf98 (&xfs_nondir_ilock_class#3){++++}-{3:3}, at: xfs_icwalk_process_inode fs/xfs/xfs_icache.c:1630 [inline]
ffff8880118eaf98 (&xfs_nondir_ilock_class#3){++++}-{3:3}, at: xfs_icwalk_ag+0x120e/0x1ad0 fs/xfs/xfs_icache.c:1712

but task is already holding lock:
ffffffff8ea2fce0 (fs_reclaim){+.+.}-{0:0}, at: balance_pgdat mm/vmscan.c:6841 [inline]
ffffffff8ea2fce0 (fs_reclaim){+.+.}-{0:0}, at: kswapd+0xbb4/0x35a0 mm/vmscan.c:7223

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (fs_reclaim){+.+.}-{0:0}:
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5759
       __fs_reclaim_acquire mm/page_alloc.c:3823 [inline]
       fs_reclaim_acquire+0x88/0x140 mm/page_alloc.c:3837
       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_llistxattr fs/xattr.c:883 [inline]
       __se_sys_llistxattr fs/xattr.c:880 [inline]
       __x64_sys_llistxattr+0x170/0x230 fs/xattr.c:880
       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

-> #0 (&xfs_nondir_ilock_class#3){++++}-{3:3}:
       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
       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+0x1090/0x14c0 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

other info that might help us debug this:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(fs_reclaim);
                               lock(&xfs_nondir_ilock_class#3);
                               lock(fs_reclaim);
  lock(&xfs_nondir_ilock_class#3);

 *** DEADLOCK ***

2 locks held by kswapd0/75:
 #0: ffffffff8ea2fce0 (fs_reclaim){+.+.}-{0:0}, at: balance_pgdat mm/vmscan.c:6841 [inline]
 #0: ffffffff8ea2fce0 (fs_reclaim){+.+.}-{0:0}, at: kswapd+0xbb4/0x35a0 mm/vmscan.c:7223
 #1: ffff888011d420e0 (&type->s_umount_key#44){.+.+}-{3:3}, at: super_trylock_shared fs/super.c:562 [inline]
 #1: ffff888011d420e0 (&type->s_umount_key#44){.+.+}-{3:3}, at: super_cache_scan+0x94/0x4b0 fs/super.c:196

stack backtrace:
CPU: 0 UID: 0 PID: 75 Comm: kswapd0 Not tainted 6.11.0-rc3-syzkaller-00013-g6b0f8db921ab #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
 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+0x1090/0x14c0 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
 </TASK>