====================================================== WARNING: possible circular locking dependency detected 6.13.0-syzkaller-02526-gc4b9570cfb63 #0 Not tainted ------------------------------------------------------ kswapd0/74 is trying to acquire lock: ffff88801d0c2490 (&delayed_node->mutex){+.+.}-{4:4}, at: __btrfs_release_delayed_node+0xa5/0xaf0 fs/btrfs/delayed-inode.c:268 but task is already holding lock: ffffffff8ea3b580 (fs_reclaim){+.+.}-{0:0}, at: balance_pgdat mm/vmscan.c:6874 [inline] ffffffff8ea3b580 (fs_reclaim){+.+.}-{0:0}, at: kswapd+0xb78/0x3670 mm/vmscan.c:7252 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:4070 [inline] slab_alloc_node mm/slub.c:4148 [inline] __kmalloc_cache_noprof+0x41/0x390 mm/slub.c:4324 kmalloc_noprof include/linux/slab.h:901 [inline] kzalloc_noprof include/linux/slab.h:1037 [inline] kobject_uevent_env+0x28b/0x8e0 lib/kobject_uevent.c:540 loop_set_size drivers/block/loop.c:235 [inline] loop_set_status+0x6c2/0x940 drivers/block/loop.c:1291 lo_ioctl+0xcd3/0x23b0 blkdev_ioctl+0x57d/0x6a0 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:629 __submit_bio_noacct_mq block/blk-core.c:716 [inline] submit_bio_noacct_nocheck+0x4d3/0xe30 block/blk-core.c:745 btrfs_submit_chunk fs/btrfs/bio.c:770 [inline] btrfs_submit_bbio+0xeb9/0x18c0 fs/btrfs/bio.c:799 read_extent_buffer_pages_nowait+0x62b/0x740 fs/btrfs/extent_io.c:3601 read_extent_buffer_pages+0x24/0x100 fs/btrfs/extent_io.c:3610 btrfs_read_extent_buffer+0xd6/0x730 fs/btrfs/disk-io.c:229 read_block_for_search+0x79e/0xbb0 fs/btrfs/ctree.c:1549 btrfs_search_slot+0x1274/0x3180 fs/btrfs/ctree.c:2170 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+0x12d8/0x1a30 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:1874 [inline] btrfs_search_slot+0x2767/0x3180 fs/btrfs/ctree.c:2122 btrfs_insert_empty_items+0x9c/0x1a0 fs/btrfs/ctree.c:4285 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 btrfs_commit_transaction+0x89a/0x3760 fs/btrfs/transaction.c:2310 create_snapshot+0x655/0x990 fs/btrfs/ioctl.c:784 btrfs_mksubvol+0x58f/0x710 fs/btrfs/ioctl.c:938 btrfs_mksnapshot+0xae/0xf0 fs/btrfs/ioctl.c:982 __btrfs_ioctl_snap_create+0x37d/0x4b0 fs/btrfs/ioctl.c:1246 btrfs_ioctl_snap_create_v2+0x1ef/0x390 fs/btrfs/ioctl.c:1327 btrfs_ioctl+0xa61/0xcf0 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 -> #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:4846 shrink_many mm/vmscan.c:4907 [inline] lru_gen_shrink_node mm/vmscan.c:4985 [inline] shrink_node+0x37c5/0x3e50 mm/vmscan.c:5966 kswapd_shrink_node mm/vmscan.c:6795 [inline] balance_pgdat mm/vmscan.c:6987 [inline] kswapd+0x1c28/0x3670 mm/vmscan.c:7252 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 --> &q->q_usage_counter(io)#17 --> fs_reclaim Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(fs_reclaim); lock(&q->q_usage_counter(io)#17); lock(fs_reclaim); lock(&delayed_node->mutex); *** DEADLOCK *** 2 locks held by kswapd0/74: #0: ffffffff8ea3b580 (fs_reclaim){+.+.}-{0:0}, at: balance_pgdat mm/vmscan.c:6874 [inline] #0: ffffffff8ea3b580 (fs_reclaim){+.+.}-{0:0}, at: kswapd+0xb78/0x3670 mm/vmscan.c:7252 #1: ffff8880441560e0 (&type->s_umount_key#50){++++}-{4:4}, at: super_trylock_shared fs/super.c:562 [inline] #1: ffff8880441560e0 (&type->s_umount_key#50){++++}-{4:4}, at: super_cache_scan+0x94/0x4b0 fs/super.c:196 stack backtrace: CPU: 0 UID: 0 PID: 74 Comm: kswapd0 Not tainted 6.13.0-syzkaller-02526-gc4b9570cfb63 #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:4846 shrink_many mm/vmscan.c:4907 [inline] lru_gen_shrink_node mm/vmscan.c:4985 [inline] shrink_node+0x37c5/0x3e50 mm/vmscan.c:5966 kswapd_shrink_node mm/vmscan.c:6795 [inline] balance_pgdat mm/vmscan.c:6987 [inline] kswapd+0x1c28/0x3670 mm/vmscan.c:7252 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