syzbot

======================================================
WARNING: possible circular locking dependency detected
6.12.0-rc7-syzkaller-00212-g4a5df3796467 #0 Not tainted
------------------------------------------------------
kswapd0/79 is trying to acquire lock:
ffff888047169098 (&xfs_nondir_ilock_class#3){++++}-{3:3}, at: xfs_reclaim_inode fs/xfs/xfs_icache.c:981 [inline]
ffff888047169098 (&xfs_nondir_ilock_class#3){++++}-{3:3}, at: xfs_icwalk_process_inode fs/xfs/xfs_icache.c:1675 [inline]
ffff888047169098 (&xfs_nondir_ilock_class#3){++++}-{3:3}, at: xfs_icwalk_ag+0x120e/0x1ad0 fs/xfs/xfs_icache.c:1757

but task is already holding lock:
ffffffff8ea37480 (fs_reclaim){+.+.}-{0:0}, at: balance_pgdat mm/vmscan.c:6850 [inline]
ffffffff8ea37480 (fs_reclaim){+.+.}-{0:0}, at: kswapd+0xbf1/0x3700 mm/vmscan.c:7232

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:5825
       __fs_reclaim_acquire mm/page_alloc.c:3851 [inline]
       fs_reclaim_acquire+0x88/0x130 mm/page_alloc.c:3865
       might_alloc include/linux/sched/mm.h:318 [inline]
       slab_pre_alloc_hook mm/slub.c:4036 [inline]
       slab_alloc_node mm/slub.c:4114 [inline]
       __do_kmalloc_node mm/slub.c:4263 [inline]
       __kmalloc_noprof+0xa9/0x400 mm/slub.c:4276
       kmalloc_noprof include/linux/slab.h:882 [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:3161 [inline]
       check_prevs_add kernel/locking/lockdep.c:3280 [inline]
       validate_chain+0x18ef/0x5920 kernel/locking/lockdep.c:3904
       __lock_acquire+0x1384/0x2050 kernel/locking/lockdep.c:5202
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5825
       down_write_nested+0xa2/0x220 kernel/locking/rwsem.c:1693
       xfs_reclaim_inode fs/xfs/xfs_icache.c:981 [inline]
       xfs_icwalk_process_inode fs/xfs/xfs_icache.c:1675 [inline]
       xfs_icwalk_ag+0x120e/0x1ad0 fs/xfs/xfs_icache.c:1757
       xfs_icwalk fs/xfs/xfs_icache.c:1805 [inline]
       xfs_reclaim_inodes_nr+0x2ae/0x390 fs/xfs/xfs_icache.c:1047
       super_cache_scan+0x40f/0x4b0 fs/super.c:227
       do_shrink_slab+0x701/0x1160 mm/shrinker.c:437
       shrink_slab+0x1093/0x14d0 mm/shrinker.c:664
       shrink_one+0x43b/0x850 mm/vmscan.c:4824
       shrink_many mm/vmscan.c:4885 [inline]
       lru_gen_shrink_node mm/vmscan.c:4963 [inline]
       shrink_node+0x3791/0x3e20 mm/vmscan.c:5943
       kswapd_shrink_node mm/vmscan.c:6771 [inline]
       balance_pgdat mm/vmscan.c:6963 [inline]
       kswapd+0x1ca9/0x3700 mm/vmscan.c:7232
       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 kswapd0/79:
 #0: ffffffff8ea37480 (fs_reclaim){+.+.}-{0:0}, at: balance_pgdat mm/vmscan.c:6850 [inline]
 #0: ffffffff8ea37480 (fs_reclaim){+.+.}-{0:0}, at: kswapd+0xbf1/0x3700 mm/vmscan.c:7232
 #1: ffff88803ff040e0 (&type->s_umount_key#43){++++}-{3:3}, at: super_trylock_shared fs/super.c:562 [inline]
 #1: ffff88803ff040e0 (&type->s_umount_key#43){++++}-{3:3}, at: super_cache_scan+0x94/0x4b0 fs/super.c:196

stack backtrace:
CPU: 0 UID: 0 PID: 79 Comm: kswapd0 Not tainted 6.12.0-rc7-syzkaller-00212-g4a5df3796467 #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:94 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
 print_circular_bug+0x13a/0x1b0 kernel/locking/lockdep.c:2074
 check_noncircular+0x36a/0x4a0 kernel/locking/lockdep.c:2206
 check_prev_add kernel/locking/lockdep.c:3161 [inline]
 check_prevs_add kernel/locking/lockdep.c:3280 [inline]
 validate_chain+0x18ef/0x5920 kernel/locking/lockdep.c:3904
 __lock_acquire+0x1384/0x2050 kernel/locking/lockdep.c:5202
 lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5825
 down_write_nested+0xa2/0x220 kernel/locking/rwsem.c:1693
 xfs_reclaim_inode fs/xfs/xfs_icache.c:981 [inline]
 xfs_icwalk_process_inode fs/xfs/xfs_icache.c:1675 [inline]
 xfs_icwalk_ag+0x120e/0x1ad0 fs/xfs/xfs_icache.c:1757
 xfs_icwalk fs/xfs/xfs_icache.c:1805 [inline]
 xfs_reclaim_inodes_nr+0x2ae/0x390 fs/xfs/xfs_icache.c:1047
 super_cache_scan+0x40f/0x4b0 fs/super.c:227
 do_shrink_slab+0x701/0x1160 mm/shrinker.c:437
 shrink_slab+0x1093/0x14d0 mm/shrinker.c:664
 shrink_one+0x43b/0x850 mm/vmscan.c:4824
 shrink_many mm/vmscan.c:4885 [inline]
 lru_gen_shrink_node mm/vmscan.c:4963 [inline]
 shrink_node+0x3791/0x3e20 mm/vmscan.c:5943
 kswapd_shrink_node mm/vmscan.c:6771 [inline]
 balance_pgdat mm/vmscan.c:6963 [inline]
 kswapd+0x1ca9/0x3700 mm/vmscan.c:7232
 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>