====================================================== WARNING: possible circular locking dependency detected 6.14.0-rc2-syzkaller-00185-g128c8f96eb86 #0 Not tainted ------------------------------------------------------ kswapd0/75 is trying to acquire lock: ffff888012e6b2a8 (&delayed_node->mutex){+.+.}-{4:4}, at: __btrfs_release_delayed_node+0xa5/0xaf0 fs/btrfs/delayed-inode.c:268 but task is already holding lock: ffffffff8ec3a140 (fs_reclaim){+.+.}-{0:0}, at: balance_pgdat mm/vmscan.c:6886 [inline] ffffffff8ec3a140 (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: -> #4 (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:668 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 -> #3 (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 loop_set_size drivers/block/loop.c:235 [inline] loop_set_status+0x4f8/0x800 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 -> #2 (&q->q_usage_counter(io)#17){++++}-{0:0}: lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5851 bio_queue_enter block/blk.h:77 [inline] blk_mq_submit_bio+0x14e1/0x25a0 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 btrfs_submit_chunk fs/btrfs/bio.c:770 [inline] btrfs_submit_bbio+0xe4e/0x18c0 fs/btrfs/bio.c:799 read_extent_buffer_pages_nowait+0x62b/0x740 fs/btrfs/extent_io.c:3612 read_extent_buffer_pages+0x24/0x100 fs/btrfs/extent_io.c:3621 btrfs_read_extent_buffer+0xd6/0x730 fs/btrfs/disk-io.c:229 read_block_for_search+0x78b/0xb90 fs/btrfs/ctree.c:1551 btrfs_search_slot+0x1274/0x3180 fs/btrfs/ctree.c:2172 btrfs_init_root_free_objectid+0x148/0x330 fs/btrfs/disk-io.c:4919 btrfs_init_fs_root fs/btrfs/disk-io.c:1137 [inline] btrfs_get_root_ref+0x5d7/0xc30 fs/btrfs/disk-io.c:1365 btrfs_get_fs_root fs/btrfs/disk-io.c:1417 [inline] open_ctree+0x24eb/0x2ab0 fs/btrfs/disk-io.c:3605 btrfs_fill_super fs/btrfs/super.c:972 [inline] btrfs_get_tree_super fs/btrfs/super.c:1898 [inline] btrfs_get_tree+0x12da/0x1a30 fs/btrfs/super.c:2093 vfs_get_tree+0x90/0x2b0 fs/super.c:1814 fc_mount+0x1b/0xb0 fs/namespace.c:1271 btrfs_get_tree_subvol fs/btrfs/super.c:2051 [inline] btrfs_get_tree+0x6b1/0x1a30 fs/btrfs/super.c:2094 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 -> #1 (btrfs-tree-00){++++}-{4:4}: reacquire_held_locks+0x3eb/0x690 kernel/locking/lockdep.c:5376 __lock_release kernel/locking/lockdep.c:5565 [inline] lock_release+0x396/0xa30 kernel/locking/lockdep.c:5872 up_write+0x79/0x590 kernel/locking/rwsem.c:1629 btrfs_tree_unlock_rw fs/btrfs/locking.h:216 [inline] btrfs_unlock_up_safe+0x179/0x3b0 fs/btrfs/locking.c:225 search_leaf fs/btrfs/ctree.c:1876 [inline] btrfs_search_slot+0x2767/0x3180 fs/btrfs/ctree.c:2124 btrfs_insert_empty_items+0x9c/0x1a0 fs/btrfs/ctree.c:4287 btrfs_insert_delayed_item fs/btrfs/delayed-inode.c:753 [inline] btrfs_insert_delayed_items fs/btrfs/delayed-inode.c:831 [inline] __btrfs_commit_inode_delayed_items+0xd5d/0x24a0 fs/btrfs/delayed-inode.c:1120 __btrfs_run_delayed_items+0x20e/0x4b0 fs/btrfs/delayed-inode.c:1165 flush_space+0x2f1/0xd30 fs/btrfs/space-info.c:782 btrfs_async_reclaim_metadata_space+0x178/0x3b0 fs/btrfs/space-info.c:1120 process_one_work kernel/workqueue.c:3236 [inline] process_scheduled_works+0xabe/0x18e0 kernel/workqueue.c:3317 worker_thread+0x870/0xd30 kernel/workqueue.c:3398 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 -> #0 (&delayed_node->mutex){+.+.}-{4:4}: 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 __mutex_lock_common kernel/locking/mutex.c:585 [inline] __mutex_lock+0x19c/0x1010 kernel/locking/mutex.c:730 __btrfs_release_delayed_node+0xa5/0xaf0 fs/btrfs/delayed-inode.c:268 btrfs_evict_inode+0x752/0x1080 fs/btrfs/inode.c:5422 evict+0x4e8/0x9a0 fs/inode.c:796 dispose_list fs/inode.c:845 [inline] prune_icache_sb+0x239/0x2f0 fs/inode.c:1033 super_cache_scan+0x38c/0x4b0 fs/super.c:223 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: &delayed_node->mutex --> uevent_sock_mutex --> fs_reclaim Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(fs_reclaim); lock(uevent_sock_mutex); lock(fs_reclaim); lock(&delayed_node->mutex); *** DEADLOCK *** 2 locks held by kswapd0/75: #0: ffffffff8ec3a140 (fs_reclaim){+.+.}-{0:0}, at: balance_pgdat mm/vmscan.c:6886 [inline] #0: ffffffff8ec3a140 (fs_reclaim){+.+.}-{0:0}, at: kswapd+0xb9f/0x3b10 mm/vmscan.c:7264 #1: ffff8880332ac0e0 (&type->s_umount_key#49){++++}-{4:4}, at: super_trylock_shared fs/super.c:562 [inline] #1: ffff8880332ac0e0 (&type->s_umount_key#49){++++}-{4:4}, at: super_cache_scan+0x94/0x4b0 fs/super.c:196 stack backtrace: CPU: 0 UID: 0 PID: 75 Comm: kswapd0 Not tainted 6.14.0-rc2-syzkaller-00185-g128c8f96eb86 #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: __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 __mutex_lock_common kernel/locking/mutex.c:585 [inline] __mutex_lock+0x19c/0x1010 kernel/locking/mutex.c:730 __btrfs_release_delayed_node+0xa5/0xaf0 fs/btrfs/delayed-inode.c:268 btrfs_evict_inode+0x752/0x1080 fs/btrfs/inode.c:5422 evict+0x4e8/0x9a0 fs/inode.c:796 dispose_list fs/inode.c:845 [inline] prune_icache_sb+0x239/0x2f0 fs/inode.c:1033 super_cache_scan+0x38c/0x4b0 fs/super.c:223 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