syzbot

======================================================
WARNING: possible circular locking dependency detected
6.14.0-rc6-syzkaller-00253-gcb82ca153949 #0 Not tainted
------------------------------------------------------
kswapd0/74 is trying to acquire lock:
ffff888030ad4610 (sb_internal#2){.+.+}-{0:0}, at: xfs_fs_dirty_inode+0x158/0x250 fs/xfs/xfs_super.c:695

but task is already holding lock:
ffffffff8ec3a700 (fs_reclaim){+.+.}-{0:0}, at: balance_pgdat mm/vmscan.c:6886 [inline]
ffffffff8ec3a700 (fs_reclaim){+.+.}-{0:0}, at: kswapd+0xb9f/0x3b10 mm/vmscan.c:7264

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #3 (fs_reclaim){+.+.}-{0:0}:
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5851
       __fs_reclaim_acquire mm/page_alloc.c:3853 [inline]
       fs_reclaim_acquire+0x88/0x130 mm/page_alloc.c:3867
       might_alloc include/linux/sched/mm.h:318 [inline]
       slab_pre_alloc_hook mm/slub.c:4066 [inline]
       slab_alloc_node mm/slub.c:4144 [inline]
       kmem_cache_alloc_node_noprof+0x48/0x380 mm/slub.c:4216
       __alloc_skb+0x1c3/0x440 net/core/skbuff.c:596
       alloc_skb include/linux/skbuff.h:1331 [inline]
       alloc_uevent_skb+0x74/0x230 lib/kobject_uevent.c:289
       uevent_net_broadcast_untagged lib/kobject_uevent.c:326 [inline]
       kobject_uevent_net_broadcast+0x2fd/0x580 lib/kobject_uevent.c:410
       kobject_uevent_env+0x57d/0x8e0 lib/kobject_uevent.c:608
       kobject_synth_uevent+0x4ef/0xae0 lib/kobject_uevent.c:207
       bus_uevent_store+0x116/0x170 drivers/base/bus.c:832
       kernfs_fop_write_iter+0x3a0/0x500 fs/kernfs/file.c:334
       new_sync_write fs/read_write.c:586 [inline]
       vfs_write+0xacf/0xd10 fs/read_write.c:679
       ksys_write+0x18f/0x2b0 fs/read_write.c:731
       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

-> #2 (uevent_sock_mutex){+.+.}-{4:4}:
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5851
       __mutex_lock_common kernel/locking/mutex.c:585 [inline]
       __mutex_lock+0x19c/0x1010 kernel/locking/mutex.c:730
       uevent_net_broadcast_untagged lib/kobject_uevent.c:317 [inline]
       kobject_uevent_net_broadcast+0x280/0x580 lib/kobject_uevent.c:410
       kobject_uevent_env+0x57d/0x8e0 lib/kobject_uevent.c:608
       set_capacity_and_notify+0x265/0x2d0 block/genhd.c:102
       loop_set_size drivers/block/loop.c:234 [inline]
       loop_set_status+0x496/0x800 drivers/block/loop.c:1292
       lo_ioctl+0xce6/0x2870
       blkdev_ioctl+0x5d0/0x6f0 block/ioctl.c:693
       vfs_ioctl fs/ioctl.c:51 [inline]
       __do_sys_ioctl fs/ioctl.c:906 [inline]
       __se_sys_ioctl+0xf5/0x170 fs/ioctl.c:892
       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

-> #1 (&q->q_usage_counter(io)#17){++++}-{0:0}:
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5851
       bio_queue_enter block/blk.h:78 [inline]
       blk_mq_submit_bio+0x14e1/0x25d0 block/blk-mq.c:3091
       __submit_bio+0x2cf/0x6a0 block/blk-core.c:628
       __submit_bio_noacct_mq block/blk-core.c:715 [inline]
       submit_bio_noacct_nocheck+0x4d3/0xe30 block/blk-core.c:744
       xfs_buf_submit_bio fs/xfs/xfs_buf.c:1504 [inline]
       xfs_buf_submit+0x933/0xdc0 fs/xfs/xfs_buf.c:1611
       _xfs_buf_read fs/xfs/xfs_buf.c:745 [inline]
       xfs_buf_read_map+0x3ad/0xb10 fs/xfs/xfs_buf.c:812
       xfs_trans_read_buf_map+0x260/0xab0 fs/xfs/xfs_trans_buf.c:304
       xfs_trans_read_buf fs/xfs/xfs_trans.h:212 [inline]
       xfs_read_agi+0x2e6/0x680 fs/xfs/libxfs/xfs_ialloc.c:2760
       xfs_ialloc_read_agi+0x16f/0x550 fs/xfs/libxfs/xfs_ialloc.c:2791
       xfs_dialloc_try_ag fs/xfs/libxfs/xfs_ialloc.c:1809 [inline]
       xfs_dialloc+0xa68/0x1e20 fs/xfs/libxfs/xfs_ialloc.c:1945
       xfs_qm_qino_alloc+0x254/0x770 fs/xfs/xfs_qm.c:1032
       xfs_qm_init_quotainos+0x60b/0x8a0 fs/xfs/xfs_qm.c:1875
       xfs_qm_init_quotainfo+0x180/0x1260 fs/xfs/xfs_qm.c:860
       xfs_qm_mount_quotas+0xe9/0x680 fs/xfs/xfs_qm.c:1726
       xfs_mountfs+0x1f3d/0x2500 fs/xfs/xfs_mount.c:1041
       xfs_fs_fill_super+0x1223/0x1550 fs/xfs/xfs_super.c:1817
       get_tree_bdev_flags+0x48c/0x5c0 fs/super.c:1636
       vfs_get_tree+0x90/0x2b0 fs/super.c:1814
       do_new_mount+0x2be/0xb40 fs/namespace.c:3560
       do_mount fs/namespace.c:3900 [inline]
       __do_sys_mount fs/namespace.c:4111 [inline]
       __se_sys_mount+0x2d6/0x3c0 fs/namespace.c:4088
       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 (sb_internal#2){.+.+}-{0:0}:
       check_prev_add kernel/locking/lockdep.c:3163 [inline]
       check_prevs_add kernel/locking/lockdep.c:3282 [inline]
       validate_chain+0x18ef/0x5920 kernel/locking/lockdep.c:3906
       __lock_acquire+0x1397/0x2100 kernel/locking/lockdep.c:5228
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5851
       percpu_down_read include/linux/percpu-rwsem.h:51 [inline]
       __sb_start_write include/linux/fs.h:1785 [inline]
       sb_start_intwrite include/linux/fs.h:1968 [inline]
       xfs_trans_alloc+0xe5/0x7f0 fs/xfs/xfs_trans.c:265
       xfs_fs_dirty_inode+0x158/0x250 fs/xfs/xfs_super.c:695
       __mark_inode_dirty+0x2ee/0xe90 fs/fs-writeback.c:2515
       mark_inode_dirty_sync include/linux/fs.h:2552 [inline]
       iput+0x1f1/0xa50 fs/inode.c:1969
       __dentry_kill+0x20d/0x630 fs/dcache.c:643
       shrink_kill+0xa9/0x2c0 fs/dcache.c:1088
       shrink_dentry_list+0x2c0/0x5b0 fs/dcache.c:1115
       prune_dcache_sb+0x10f/0x180 fs/dcache.c:1196
       super_cache_scan+0x34f/0x4b0 fs/super.c:221
       do_shrink_slab+0x72d/0x1160 mm/shrinker.c:437
       shrink_slab_memcg mm/shrinker.c:550 [inline]
       shrink_slab+0x878/0x14d0 mm/shrinker.c:628
       shrink_one+0x43b/0x850 mm/vmscan.c:4868
       shrink_many mm/vmscan.c:4929 [inline]
       lru_gen_shrink_node mm/vmscan.c:5007 [inline]
       shrink_node+0x379b/0x3e20 mm/vmscan.c:5978
       kswapd_shrink_node mm/vmscan.c:6807 [inline]
       balance_pgdat mm/vmscan.c:6999 [inline]
       kswapd+0x20f3/0x3b10 mm/vmscan.c:7264
       kthread+0x7a9/0x920 kernel/kthread.c:464
       ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:148
       ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

other info that might help us debug this:

Chain exists of:
  sb_internal#2 --> uevent_sock_mutex --> fs_reclaim

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(fs_reclaim);
                               lock(uevent_sock_mutex);
                               lock(fs_reclaim);
  rlock(sb_internal#2);

 *** DEADLOCK ***

2 locks held by kswapd0/74:
 #0: ffffffff8ec3a700 (fs_reclaim){+.+.}-{0:0}, at: balance_pgdat mm/vmscan.c:6886 [inline]
 #0: ffffffff8ec3a700 (fs_reclaim){+.+.}-{0:0}, at: kswapd+0xb9f/0x3b10 mm/vmscan.c:7264
 #1: ffff888030ad40e0 (&type->s_umount_key#49){.+.+}-{4:4}, at: super_trylock_shared fs/super.c:562 [inline]
 #1: ffff888030ad40e0 (&type->s_umount_key#49){.+.+}-{4:4}, at: super_cache_scan+0x94/0x4b0 fs/super.c:196

stack backtrace:
CPU: 0 UID: 0 PID: 74 Comm: kswapd0 Not tainted 6.14.0-rc6-syzkaller-00253-gcb82ca153949 #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:2076
 check_noncircular+0x36a/0x4a0 kernel/locking/lockdep.c:2208
 check_prev_add kernel/locking/lockdep.c:3163 [inline]
 check_prevs_add kernel/locking/lockdep.c:3282 [inline]
 validate_chain+0x18ef/0x5920 kernel/locking/lockdep.c:3906
 __lock_acquire+0x1397/0x2100 kernel/locking/lockdep.c:5228
 lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5851
 percpu_down_read include/linux/percpu-rwsem.h:51 [inline]
 __sb_start_write include/linux/fs.h:1785 [inline]
 sb_start_intwrite include/linux/fs.h:1968 [inline]
 xfs_trans_alloc+0xe5/0x7f0 fs/xfs/xfs_trans.c:265
 xfs_fs_dirty_inode+0x158/0x250 fs/xfs/xfs_super.c:695
 __mark_inode_dirty+0x2ee/0xe90 fs/fs-writeback.c:2515
 mark_inode_dirty_sync include/linux/fs.h:2552 [inline]
 iput+0x1f1/0xa50 fs/inode.c:1969
 __dentry_kill+0x20d/0x630 fs/dcache.c:643
 shrink_kill+0xa9/0x2c0 fs/dcache.c:1088
 shrink_dentry_list+0x2c0/0x5b0 fs/dcache.c:1115
 prune_dcache_sb+0x10f/0x180 fs/dcache.c:1196
 super_cache_scan+0x34f/0x4b0 fs/super.c:221
 do_shrink_slab+0x72d/0x1160 mm/shrinker.c:437
 shrink_slab_memcg mm/shrinker.c:550 [inline]
 shrink_slab+0x878/0x14d0 mm/shrinker.c:628
 shrink_one+0x43b/0x850 mm/vmscan.c:4868
 shrink_many mm/vmscan.c:4929 [inline]
 lru_gen_shrink_node mm/vmscan.c:5007 [inline]
 shrink_node+0x379b/0x3e20 mm/vmscan.c:5978
 kswapd_shrink_node mm/vmscan.c:6807 [inline]
 balance_pgdat mm/vmscan.c:6999 [inline]
 kswapd+0x20f3/0x3b10 mm/vmscan.c:7264
 kthread+0x7a9/0x920 kernel/kthread.c:464
 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>