syzbot

======================================================
WARNING: possible circular locking dependency detected
6.9.0-rc7-syzkaller #0 Not tainted
------------------------------------------------------
kswapd0/90 is trying to acquire lock:
ffff888056485658 (&xfs_nondir_ilock_class#3){++++}-{3:3}, at: xfs_reclaim_inode fs/xfs/xfs_icache.c:945 [inline]
ffff888056485658 (&xfs_nondir_ilock_class#3){++++}-{3:3}, at: xfs_icwalk_process_inode fs/xfs/xfs_icache.c:1631 [inline]
ffff888056485658 (&xfs_nondir_ilock_class#3){++++}-{3:3}, at: xfs_icwalk_ag+0x120e/0x1ad0 fs/xfs/xfs_icache.c:1713

but task is already holding lock:
ffffffff8e42a780 (fs_reclaim){+.+.}-{0:0}, at: balance_pgdat mm/vmscan.c:6782 [inline]
ffffffff8e42a780 (fs_reclaim){+.+.}-{0:0}, at: kswapd+0xbe8/0x38a0 mm/vmscan.c:7164

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:5754
       __fs_reclaim_acquire mm/page_alloc.c:3698 [inline]
       fs_reclaim_acquire+0x88/0x140 mm/page_alloc.c:3712
       might_alloc include/linux/sched/mm.h:312 [inline]
       slab_pre_alloc_hook mm/slub.c:3746 [inline]
       slab_alloc_node mm/slub.c:3827 [inline]
       kmalloc_trace+0x47/0x360 mm/slub.c:3992
       kmalloc include/linux/slab.h:628 [inline]
       add_stack_record_to_list mm/page_owner.c:177 [inline]
       inc_stack_record_count mm/page_owner.c:219 [inline]
       __set_page_owner+0x561/0x810 mm/page_owner.c:334
       set_page_owner include/linux/page_owner.h:32 [inline]
       post_alloc_hook+0x1ea/0x210 mm/page_alloc.c:1534
       prep_new_page mm/page_alloc.c:1541 [inline]
       get_page_from_freelist+0x3410/0x35b0 mm/page_alloc.c:3317
       __alloc_pages+0x256/0x6c0 mm/page_alloc.c:4575
       __alloc_pages_node include/linux/gfp.h:238 [inline]
       alloc_pages_node include/linux/gfp.h:261 [inline]
       alloc_slab_page+0x5f/0x160 mm/slub.c:2175
       allocate_slab mm/slub.c:2338 [inline]
       new_slab+0x84/0x2f0 mm/slub.c:2391
       ___slab_alloc+0xc73/0x1260 mm/slub.c:3525
       __slab_alloc mm/slub.c:3610 [inline]
       __slab_alloc_node mm/slub.c:3663 [inline]
       slab_alloc_node mm/slub.c:3835 [inline]
       kmem_cache_alloc+0x252/0x340 mm/slub.c:3852
       kmem_cache_zalloc include/linux/slab.h:739 [inline]
       xfs_btree_alloc_cursor fs/xfs/libxfs/xfs_btree.h:679 [inline]
       xfs_refcountbt_init_cursor+0x65/0x2a0 fs/xfs/libxfs/xfs_refcount_btree.c:367
       xfs_reflink_find_shared fs/xfs/xfs_reflink.c:147 [inline]
       xfs_reflink_trim_around_shared+0x53a/0x9d0 fs/xfs/xfs_reflink.c:194
       xfs_buffered_write_iomap_begin+0xebf/0x1b40 fs/xfs/xfs_iomap.c:1062
       iomap_iter+0x693/0xf60 fs/iomap/iter.c:91
       iomap_zero_range+0x16e/0x6e0 fs/iomap/buffered-io.c:1426
       xfs_file_write_checks+0x90d/0xb20 fs/xfs/xfs_file.c:478
       xfs_file_dio_write_aligned+0xe5/0x2c0 fs/xfs/xfs_file.c:594
       xfs_file_dio_write fs/xfs/xfs_file.c:720 [inline]
       xfs_file_write_iter+0x50d/0x620 fs/xfs/xfs_file.c:856
       do_iter_readv_writev+0x5a6/0x800
       vfs_writev+0x395/0xbb0 fs/read_write.c:971
       do_pwritev fs/read_write.c:1072 [inline]
       __do_sys_pwritev2 fs/read_write.c:1131 [inline]
       __se_sys_pwritev2+0x1ca/0x2d0 fs/read_write.c:1122
       do_syscall_x64 arch/x86/entry/common.c:52 [inline]
       do_syscall_64+0xf5/0x240 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:3134 [inline]
       check_prevs_add kernel/locking/lockdep.c:3253 [inline]
       validate_chain+0x18cb/0x58e0 kernel/locking/lockdep.c:3869
       __lock_acquire+0x1346/0x1fd0 kernel/locking/lockdep.c:5137
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5754
       down_write_nested+0x3d/0x50 kernel/locking/rwsem.c:1695
       xfs_reclaim_inode fs/xfs/xfs_icache.c:945 [inline]
       xfs_icwalk_process_inode fs/xfs/xfs_icache.c:1631 [inline]
       xfs_icwalk_ag+0x120e/0x1ad0 fs/xfs/xfs_icache.c:1713
       xfs_icwalk fs/xfs/xfs_icache.c:1762 [inline]
       xfs_reclaim_inodes_nr+0x257/0x360 fs/xfs/xfs_icache.c:1011
       super_cache_scan+0x411/0x4b0 fs/super.c:227
       do_shrink_slab+0x707/0x1160 mm/shrinker.c:435
       shrink_slab+0x1092/0x14d0 mm/shrinker.c:662
       shrink_one+0x453/0x880 mm/vmscan.c:4774
       shrink_many mm/vmscan.c:4835 [inline]
       lru_gen_shrink_node mm/vmscan.c:4935 [inline]
       shrink_node+0x3b17/0x4310 mm/vmscan.c:5894
       kswapd_shrink_node mm/vmscan.c:6704 [inline]
       balance_pgdat mm/vmscan.c:6895 [inline]
       kswapd+0x1882/0x38a0 mm/vmscan.c:7164
       kthread+0x2f2/0x390 kernel/kthread.c:388
       ret_from_fork+0x4d/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 kswapd0/90:
 #0: ffffffff8e42a780 (fs_reclaim){+.+.}-{0:0}, at: balance_pgdat mm/vmscan.c:6782 [inline]
 #0: ffffffff8e42a780 (fs_reclaim){+.+.}-{0:0}, at: kswapd+0xbe8/0x38a0 mm/vmscan.c:7164
 #1: ffff8880b4d1a0e0 (&type->s_umount_key#66){++++}-{3:3}, at: super_trylock_shared fs/super.c:561 [inline]
 #1: ffff8880b4d1a0e0 (&type->s_umount_key#66){++++}-{3:3}, at: super_cache_scan+0x94/0x4b0 fs/super.c:196

stack backtrace:
CPU: 1 PID: 90 Comm: kswapd0 Not tainted 6.9.0-rc7-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:114
 check_noncircular+0x36a/0x4a0 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+0x18cb/0x58e0 kernel/locking/lockdep.c:3869
 __lock_acquire+0x1346/0x1fd0 kernel/locking/lockdep.c:5137
 lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5754
 down_write_nested+0x3d/0x50 kernel/locking/rwsem.c:1695
 xfs_reclaim_inode fs/xfs/xfs_icache.c:945 [inline]
 xfs_icwalk_process_inode fs/xfs/xfs_icache.c:1631 [inline]
 xfs_icwalk_ag+0x120e/0x1ad0 fs/xfs/xfs_icache.c:1713
 xfs_icwalk fs/xfs/xfs_icache.c:1762 [inline]
 xfs_reclaim_inodes_nr+0x257/0x360 fs/xfs/xfs_icache.c:1011
 super_cache_scan+0x411/0x4b0 fs/super.c:227
 do_shrink_slab+0x707/0x1160 mm/shrinker.c:435
 shrink_slab+0x1092/0x14d0 mm/shrinker.c:662
 shrink_one+0x453/0x880 mm/vmscan.c:4774
 shrink_many mm/vmscan.c:4835 [inline]
 lru_gen_shrink_node mm/vmscan.c:4935 [inline]
 shrink_node+0x3b17/0x4310 mm/vmscan.c:5894
 kswapd_shrink_node mm/vmscan.c:6704 [inline]
 balance_pgdat mm/vmscan.c:6895 [inline]
 kswapd+0x1882/0x38a0 mm/vmscan.c:7164
 kthread+0x2f2/0x390 kernel/kthread.c:388
 ret_from_fork+0x4d/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>