syzbot

======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
kswapd1/78 is trying to acquire lock:
ffff88805299d558 (&inode->ei_quota_lock){+.+.}-{4:4}, at: bch2_i_sectors_acct fs/bcachefs/fs-io.h:137 [inline]
ffff88805299d558 (&inode->ei_quota_lock){+.+.}-{4:4}, at: bch2_clear_folio_bits+0x506/0x830 fs/bcachefs/fs-io-pagecache.c:513

but task is already holding lock:
ffffffff8e4419a0 (fs_reclaim){+.+.}-{0:0}, at: balance_pgdat mm/vmscan.c:7012 [inline]
ffffffff8e4419a0 (fs_reclaim){+.+.}-{0:0}, at: kswapd+0x951/0x2830 mm/vmscan.c:7386

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (fs_reclaim){+.+.}-{0:0}:
       lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868
       __fs_reclaim_acquire mm/page_alloc.c:4234 [inline]
       fs_reclaim_acquire+0x72/0x100 mm/page_alloc.c:4248
       might_alloc include/linux/sched/mm.h:318 [inline]
       slab_pre_alloc_hook mm/slub.c:4142 [inline]
       slab_alloc_node mm/slub.c:4220 [inline]
       __kmalloc_cache_noprof+0x41/0x3d0 mm/slub.c:4402
       kmalloc_noprof include/linux/slab.h:905 [inline]
       kzalloc_noprof include/linux/slab.h:1039 [inline]
       genradix_alloc_node include/linux/generic-radix-tree.h:101 [inline]
       __genradix_ptr_alloc+0x199/0x4a0 lib/generic-radix-tree.c:44
       bch2_quota_transfer+0x300/0xa50 fs/bcachefs/quota.c:343
       bch2_fs_quota_transfer+0x27d/0x4f0 fs/bcachefs/fs.c:183
       bch2_set_projid fs/bcachefs/fs.h:166 [inline]
       bch2_fileattr_set+0x515/0x6f0 fs/bcachefs/fs.c:1728
       vfs_fileattr_set+0x92f/0xb90 fs/file_attr.c:298
       ioctl_fssetxattr+0x1ed/0x270 fs/file_attr.c:372
       do_vfs_ioctl+0x81d/0x1430 fs/ioctl.c:567
       __do_sys_ioctl fs/ioctl.c:596 [inline]
       __se_sys_ioctl+0x82/0x170 fs/ioctl.c:584
       do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
       do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #0 (&inode->ei_quota_lock){+.+.}-{4:4}:
       check_prev_add kernel/locking/lockdep.c:3165 [inline]
       check_prevs_add kernel/locking/lockdep.c:3284 [inline]
       validate_chain+0xb9b/0x2140 kernel/locking/lockdep.c:3908
       __lock_acquire+0xab9/0xd20 kernel/locking/lockdep.c:5237
       lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868
       __mutex_lock_common kernel/locking/mutex.c:598 [inline]
       __mutex_lock+0x187/0x1350 kernel/locking/mutex.c:760
       bch2_i_sectors_acct fs/bcachefs/fs-io.h:137 [inline]
       bch2_clear_folio_bits+0x506/0x830 fs/bcachefs/fs-io-pagecache.c:513
       bch2_release_folio+0xf7/0x150 fs/bcachefs/fs-io-pagecache.c:672
       shrink_folio_list+0x20ac/0x4cd0 mm/vmscan.c:1518
       evict_folios+0x471e/0x57c0 mm/vmscan.c:4744
       try_to_shrink_lruvec+0x8a3/0xb50 mm/vmscan.c:4907
       shrink_one+0x21b/0x7c0 mm/vmscan.c:4952
       shrink_many mm/vmscan.c:5015 [inline]
       lru_gen_shrink_node mm/vmscan.c:5093 [inline]
       shrink_node+0x314e/0x3760 mm/vmscan.c:6078
       kswapd_shrink_node mm/vmscan.c:6938 [inline]
       balance_pgdat mm/vmscan.c:7121 [inline]
       kswapd+0x147c/0x2830 mm/vmscan.c:7386
       kthread+0x711/0x8a0 kernel/kthread.c:463
       ret_from_fork+0x439/0x7d0 arch/x86/kernel/process.c:148
       ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

other info that might help us debug this:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(fs_reclaim);
                               lock(&inode->ei_quota_lock);
                               lock(fs_reclaim);
  lock(&inode->ei_quota_lock);

 *** DEADLOCK ***

1 lock held by kswapd1/78:
 #0: ffffffff8e4419a0 (fs_reclaim){+.+.}-{0:0}, at: balance_pgdat mm/vmscan.c:7012 [inline]
 #0: ffffffff8e4419a0 (fs_reclaim){+.+.}-{0:0}, at: kswapd+0x951/0x2830 mm/vmscan.c:7386

stack backtrace:
CPU: 0 UID: 0 PID: 78 Comm: kswapd1 Not tainted syzkaller #0 PREEMPT(full) 
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_lvl+0x189/0x250 lib/dump_stack.c:120
 print_circular_bug+0x2ee/0x310 kernel/locking/lockdep.c:2043
 check_noncircular+0x134/0x160 kernel/locking/lockdep.c:2175
 check_prev_add kernel/locking/lockdep.c:3165 [inline]
 check_prevs_add kernel/locking/lockdep.c:3284 [inline]
 validate_chain+0xb9b/0x2140 kernel/locking/lockdep.c:3908
 __lock_acquire+0xab9/0xd20 kernel/locking/lockdep.c:5237
 lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868
 __mutex_lock_common kernel/locking/mutex.c:598 [inline]
 __mutex_lock+0x187/0x1350 kernel/locking/mutex.c:760
 bch2_i_sectors_acct fs/bcachefs/fs-io.h:137 [inline]
 bch2_clear_folio_bits+0x506/0x830 fs/bcachefs/fs-io-pagecache.c:513
 bch2_release_folio+0xf7/0x150 fs/bcachefs/fs-io-pagecache.c:672
 shrink_folio_list+0x20ac/0x4cd0 mm/vmscan.c:1518
 evict_folios+0x471e/0x57c0 mm/vmscan.c:4744
 try_to_shrink_lruvec+0x8a3/0xb50 mm/vmscan.c:4907
 shrink_one+0x21b/0x7c0 mm/vmscan.c:4952
 shrink_many mm/vmscan.c:5015 [inline]
 lru_gen_shrink_node mm/vmscan.c:5093 [inline]
 shrink_node+0x314e/0x3760 mm/vmscan.c:6078
 kswapd_shrink_node mm/vmscan.c:6938 [inline]
 balance_pgdat mm/vmscan.c:7121 [inline]
 kswapd+0x147c/0x2830 mm/vmscan.c:7386
 kthread+0x711/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x439/0x7d0 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>