[syzbot] [reiserfs?] possible deadlock in balance_pgdat

[syzbot <syzbot+bb678557e871cd928756@syzkaller.appspotmail.com>]

Hello,

syzbot found the following issue on:

HEAD commit:    ae3419fbac84 vc_screen: don't clobber return value in vcs_..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=10721d60c80000
kernel config:  https://syzkaller.appspot.com/x/.config?x=ff98a3b3c1aed3ab
dashboard link: https://syzkaller.appspot.com/bug?extid=bb678557e871cd928756
compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2

Unfortunately, I don't have any reproducer for this issue yet.

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+bb678557e871cd928756@syzkaller.appspotmail.com

======================================================
WARNING: possible circular locking dependency detected
6.2.0-syzkaller-12913-gae3419fbac84 #0 Not tainted
------------------------------------------------------
kswapd0/100 is trying to acquire lock:
ffff88801f2f4090 (&sbi->lock){+.+.}-{3:3}, at: reiserfs_write_lock+0x79/0x100 fs/reiserfs/lock.c:27

but task is already holding lock:
ffffffff8c8e29e0 (fs_reclaim){+.+.}-{0:0}, at: set_task_reclaim_state mm/vmscan.c:200 [inline]
ffffffff8c8e29e0 (fs_reclaim){+.+.}-{0:0}, at: balance_pgdat+0x170/0x1ac0 mm/vmscan.c:7338

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (fs_reclaim){+.+.}-{0:0}:
       __fs_reclaim_acquire mm/page_alloc.c:4716 [inline]
       fs_reclaim_acquire+0x11d/0x160 mm/page_alloc.c:4730
       might_alloc include/linux/sched/mm.h:271 [inline]
       slab_pre_alloc_hook mm/slab.h:728 [inline]
       slab_alloc_node mm/slab.c:3241 [inline]
       slab_alloc mm/slab.c:3266 [inline]
       __kmem_cache_alloc_lru mm/slab.c:3443 [inline]
       kmem_cache_alloc_lru+0x3e/0x5d0 mm/slab.c:3459
       __d_alloc+0x32/0x980 fs/dcache.c:1769
       d_alloc_anon fs/dcache.c:1868 [inline]
       d_make_root+0x49/0x110 fs/dcache.c:2069
       reiserfs_fill_super+0x1301/0x2ea0 fs/reiserfs/super.c:2083
       mount_bdev+0x351/0x410 fs/super.c:1371
       legacy_get_tree+0x109/0x220 fs/fs_context.c:610
       vfs_get_tree+0x8d/0x350 fs/super.c:1501
       do_new_mount fs/namespace.c:3042 [inline]
       path_mount+0x1342/0x1e40 fs/namespace.c:3372
       do_mount fs/namespace.c:3385 [inline]
       __do_sys_mount fs/namespace.c:3594 [inline]
       __se_sys_mount fs/namespace.c:3571 [inline]
       __x64_sys_mount+0x283/0x300 fs/namespace.c:3571
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x63/0xcd

-> #0 (&sbi->lock){+.+.}-{3:3}:
       check_prev_add kernel/locking/lockdep.c:3098 [inline]
       check_prevs_add kernel/locking/lockdep.c:3217 [inline]
       validate_chain kernel/locking/lockdep.c:3832 [inline]
       __lock_acquire+0x2ec7/0x5d40 kernel/locking/lockdep.c:5056
       lock_acquire kernel/locking/lockdep.c:5669 [inline]
       lock_acquire+0x1e3/0x670 kernel/locking/lockdep.c:5634
       __mutex_lock_common kernel/locking/mutex.c:603 [inline]
       __mutex_lock+0x12f/0x1350 kernel/locking/mutex.c:747
       reiserfs_write_lock+0x79/0x100 fs/reiserfs/lock.c:27
       reiserfs_evict_inode+0x30b/0x540 fs/reiserfs/inode.c:55
       evict+0x2ed/0x6b0 fs/inode.c:665
       iput_final fs/inode.c:1748 [inline]
       iput.part.0+0x59b/0x8a0 fs/inode.c:1774
       iput+0x5c/0x80 fs/inode.c:1764
       dentry_unlink_inode+0x2b1/0x460 fs/dcache.c:401
       __dentry_kill+0x3c0/0x640 fs/dcache.c:607
       shrink_dentry_list+0x12c/0x4f0 fs/dcache.c:1201
       prune_dcache_sb+0xeb/0x150 fs/dcache.c:1282
       super_cache_scan+0x33a/0x590 fs/super.c:104
       do_shrink_slab+0x464/0xd20 mm/vmscan.c:853
       shrink_slab_memcg mm/vmscan.c:922 [inline]
       shrink_slab+0x388/0x660 mm/vmscan.c:1001
       shrink_one+0x502/0x810 mm/vmscan.c:5343
       shrink_many mm/vmscan.c:5394 [inline]
       lru_gen_shrink_node mm/vmscan.c:5511 [inline]
       shrink_node+0x2064/0x35f0 mm/vmscan.c:6459
       kswapd_shrink_node mm/vmscan.c:7262 [inline]
       balance_pgdat+0xa02/0x1ac0 mm/vmscan.c:7452
       kswapd+0x70b/0x1000 mm/vmscan.c:7712
       kthread+0x2e8/0x3a0 kernel/kthread.c:376
       ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308

other info that might help us debug this:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(fs_reclaim);
                               lock(&sbi->lock);
                               lock(fs_reclaim);
  lock(&sbi->lock);

 *** DEADLOCK ***

3 locks held by kswapd0/100:
 #0: ffffffff8c8e29e0 (fs_reclaim){+.+.}-{0:0}, at: set_task_reclaim_state mm/vmscan.c:200 [inline]
 #0: ffffffff8c8e29e0 (fs_reclaim){+.+.}-{0:0}, at: balance_pgdat+0x170/0x1ac0 mm/vmscan.c:7338
 #1: ffffffff8c8995d0 (shrinker_rwsem){++++}-{3:3}, at: shrink_slab_memcg mm/vmscan.c:895 [inline]
 #1: ffffffff8c8995d0 (shrinker_rwsem){++++}-{3:3}, at: shrink_slab+0x2a0/0x660 mm/vmscan.c:1001
 #2: ffff88801230a0e0 (&type->s_umount_key#64){++++}-{3:3}, at: trylock_super fs/super.c:414 [inline]
 #2: ffff88801230a0e0 (&type->s_umount_key#64){++++}-{3:3}, at: super_cache_scan+0x70/0x590 fs/super.c:79

stack backtrace:
CPU: 2 PID: 100 Comm: kswapd0 Not tainted 6.2.0-syzkaller-12913-gae3419fbac84 #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-2 04/01/2014
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xd9/0x150 lib/dump_stack.c:106
 check_noncircular+0x25f/0x2e0 kernel/locking/lockdep.c:2178
 check_prev_add kernel/locking/lockdep.c:3098 [inline]
 check_prevs_add kernel/locking/lockdep.c:3217 [inline]
 validate_chain kernel/locking/lockdep.c:3832 [inline]
 __lock_acquire+0x2ec7/0x5d40 kernel/locking/lockdep.c:5056
 lock_acquire kernel/locking/lockdep.c:5669 [inline]
 lock_acquire+0x1e3/0x670 kernel/locking/lockdep.c:5634
 __mutex_lock_common kernel/locking/mutex.c:603 [inline]
 __mutex_lock+0x12f/0x1350 kernel/locking/mutex.c:747
 reiserfs_write_lock+0x79/0x100 fs/reiserfs/lock.c:27
 reiserfs_evict_inode+0x30b/0x540 fs/reiserfs/inode.c:55
 evict+0x2ed/0x6b0 fs/inode.c:665
 iput_final fs/inode.c:1748 [inline]
 iput.part.0+0x59b/0x8a0 fs/inode.c:1774
 iput+0x5c/0x80 fs/inode.c:1764
 dentry_unlink_inode+0x2b1/0x460 fs/dcache.c:401
 __dentry_kill+0x3c0/0x640 fs/dcache.c:607
 shrink_dentry_list+0x12c/0x4f0 fs/dcache.c:1201
 prune_dcache_sb+0xeb/0x150 fs/dcache.c:1282
 super_cache_scan+0x33a/0x590 fs/super.c:104
 do_shrink_slab+0x464/0xd20 mm/vmscan.c:853
 shrink_slab_memcg mm/vmscan.c:922 [inline]
 shrink_slab+0x388/0x660 mm/vmscan.c:1001
 shrink_one+0x502/0x810 mm/vmscan.c:5343
 shrink_many mm/vmscan.c:5394 [inline]
 lru_gen_shrink_node mm/vmscan.c:5511 [inline]
 shrink_node+0x2064/0x35f0 mm/vmscan.c:6459
 kswapd_shrink_node mm/vmscan.c:7262 [inline]
 balance_pgdat+0xa02/0x1ac0 mm/vmscan.c:7452
 kswapd+0x70b/0x1000 mm/vmscan.c:7712
 kthread+0x2e8/0x3a0 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308
 </TASK>


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.