====================================================== WARNING: possible circular locking dependency detected 6.12.0-next-20241128-syzkaller #0 Not tainted ------------------------------------------------------ kworker/u8:12/6861 is trying to acquire lock: ffff88803171b3b8 (btrfs-tree-01){++++}-{4:4}, at: btrfs_tree_read_lock_nested+0x2f/0x250 fs/btrfs/locking.c:146 but task is already holding lock: ffff888071adc860 (&delayed_node->mutex){+.+.}-{4:4}, at: btrfs_insert_delayed_items fs/btrfs/delayed-inode.c:830 [inline] ffff888071adc860 (&delayed_node->mutex){+.+.}-{4:4}, at: __btrfs_commit_inode_delayed_items+0x1c4/0x24a0 fs/btrfs/delayed-inode.c:1126 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #4 (&delayed_node->mutex){+.+.}-{4:4}: lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5849 __mutex_lock_common kernel/locking/mutex.c:585 [inline] __mutex_lock+0x1ac/0xee0 kernel/locking/mutex.c:735 __btrfs_release_delayed_node+0xa5/0xaf0 fs/btrfs/delayed-inode.c:268 btrfs_evict_inode+0x752/0x1080 fs/btrfs/inode.c:5374 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:4836 shrink_many mm/vmscan.c:4897 [inline] lru_gen_shrink_node mm/vmscan.c:4975 [inline] shrink_node+0x37c5/0x3e50 mm/vmscan.c:5956 kswapd_shrink_node mm/vmscan.c:6785 [inline] balance_pgdat mm/vmscan.c:6977 [inline] kswapd+0x1ca9/0x36f0 mm/vmscan.c:7246 kthread+0x2f0/0x390 kernel/kthread.c:389 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 -> #3 (fs_reclaim){+.+.}-{0:0}: lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5849 __fs_reclaim_acquire mm/page_alloc.c:3887 [inline] fs_reclaim_acquire+0x88/0x130 mm/page_alloc.c:3901 might_alloc include/linux/sched/mm.h:318 [inline] slab_pre_alloc_hook mm/slub.c:4055 [inline] slab_alloc_node mm/slub.c:4133 [inline] __kmalloc_cache_noprof+0x41/0x390 mm/slub.c:4309 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:233 [inline] loop_set_status+0x5f0/0x8f0 drivers/block/loop.c:1285 lo_ioctl+0xcbc/0x1f50 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:5849 bio_queue_enter block/blk.h:75 [inline] blk_mq_submit_bio+0x1536/0x2390 block/blk-mq.c:3091 __submit_bio+0x2c6/0x560 block/blk-core.c:629 __submit_bio_noacct_mq block/blk-core.c:710 [inline] submit_bio_noacct_nocheck+0x4d3/0xe30 block/blk-core.c:739 btrfs_submit_chunk fs/btrfs/bio.c:745 [inline] btrfs_submit_bbio+0xf93/0x18e0 fs/btrfs/bio.c:773 read_extent_buffer_pages+0x65a/0x910 fs/btrfs/extent_io.c:3558 btrfs_read_extent_buffer+0xd9/0x770 fs/btrfs/disk-io.c:229 read_block_for_search+0x79e/0xbb0 fs/btrfs/ctree.c:1619 btrfs_search_slot+0x121b/0x3150 fs/btrfs/ctree.c:2236 btrfs_init_root_free_objectid+0x148/0x330 fs/btrfs/disk-io.c:4837 btrfs_init_fs_root fs/btrfs/disk-io.c:1137 [inline] btrfs_get_root_ref+0x5d7/0xc30 fs/btrfs/disk-io.c:1364 btrfs_get_fs_root fs/btrfs/disk-io.c:1416 [inline] open_ctree+0x2470/0x2a30 fs/btrfs/disk-io.c:3532 btrfs_fill_super fs/btrfs/super.c:972 [inline] btrfs_get_tree_super fs/btrfs/super.c:1894 [inline] btrfs_get_tree+0x1274/0x1a10 fs/btrfs/super.c:2105 vfs_get_tree+0x90/0x2b0 fs/super.c:1814 fc_mount+0x1b/0xb0 fs/namespace.c:1231 btrfs_get_tree_subvol fs/btrfs/super.c:2068 [inline] btrfs_get_tree+0x65b/0x1a10 fs/btrfs/super.c:2106 vfs_get_tree+0x90/0x2b0 fs/super.c:1814 do_new_mount+0x2be/0xb40 fs/namespace.c:3507 do_mount fs/namespace.c:3847 [inline] __do_sys_mount fs/namespace.c:4057 [inline] __se_sys_mount+0x2d6/0x3c0 fs/namespace.c:4034 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}: lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5849 down_read_nested+0xb5/0xa50 kernel/locking/rwsem.c:1649 btrfs_tree_read_lock_nested+0x2f/0x250 fs/btrfs/locking.c:146 btrfs_tree_read_lock fs/btrfs/locking.h:178 [inline] read_block_for_search+0x718/0xbb0 fs/btrfs/ctree.c:1613 btrfs_search_slot+0x121b/0x3150 fs/btrfs/ctree.c:2236 btrfs_init_root_free_objectid+0x148/0x330 fs/btrfs/disk-io.c:4837 btrfs_init_fs_root fs/btrfs/disk-io.c:1137 [inline] btrfs_get_root_ref+0x5d7/0xc30 fs/btrfs/disk-io.c:1364 btrfs_get_fs_root fs/btrfs/disk-io.c:1416 [inline] open_ctree+0x2470/0x2a30 fs/btrfs/disk-io.c:3532 btrfs_fill_super fs/btrfs/super.c:972 [inline] btrfs_get_tree_super fs/btrfs/super.c:1894 [inline] btrfs_get_tree+0x1274/0x1a10 fs/btrfs/super.c:2105 vfs_get_tree+0x90/0x2b0 fs/super.c:1814 fc_mount+0x1b/0xb0 fs/namespace.c:1231 btrfs_get_tree_subvol fs/btrfs/super.c:2068 [inline] btrfs_get_tree+0x65b/0x1a10 fs/btrfs/super.c:2106 vfs_get_tree+0x90/0x2b0 fs/super.c:1814 do_new_mount+0x2be/0xb40 fs/namespace.c:3507 do_mount fs/namespace.c:3847 [inline] __do_sys_mount fs/namespace.c:4057 [inline] __se_sys_mount+0x2d6/0x3c0 fs/namespace.c:4034 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 (btrfs-tree-01){++++}-{4:4}: check_prev_add kernel/locking/lockdep.c:3161 [inline] check_prevs_add kernel/locking/lockdep.c:3280 [inline] validate_chain+0x18ef/0x5920 kernel/locking/lockdep.c:3904 __lock_acquire+0x1397/0x2100 kernel/locking/lockdep.c:5226 lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5849 down_read_nested+0xb5/0xa50 kernel/locking/rwsem.c:1649 btrfs_tree_read_lock_nested+0x2f/0x250 fs/btrfs/locking.c:146 btrfs_tree_read_lock fs/btrfs/locking.h:178 [inline] btrfs_read_lock_root_node+0x3f/0xd0 fs/btrfs/locking.c:267 btrfs_search_slot_get_root fs/btrfs/ctree.c:1790 [inline] btrfs_search_slot+0x4f7/0x3150 fs/btrfs/ctree.c:2112 btrfs_insert_empty_items+0x9c/0x1a0 fs/btrfs/ctree.c:4350 btrfs_insert_delayed_item fs/btrfs/delayed-inode.c:758 [inline] btrfs_insert_delayed_items fs/btrfs/delayed-inode.c:836 [inline] __btrfs_commit_inode_delayed_items+0xd5d/0x24a0 fs/btrfs/delayed-inode.c:1126 __btrfs_run_delayed_items+0x213/0x490 fs/btrfs/delayed-inode.c:1171 flush_space+0x24a/0xcf0 fs/btrfs/space-info.c:775 btrfs_async_reclaim_metadata_space+0x113/0x350 fs/btrfs/space-info.c:1105 process_one_work kernel/workqueue.c:3229 [inline] process_scheduled_works+0xa66/0x1840 kernel/workqueue.c:3310 worker_thread+0x870/0xd30 kernel/workqueue.c:3391 kthread+0x2f0/0x390 kernel/kthread.c:389 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 other info that might help us debug this: Chain exists of: btrfs-tree-01 --> fs_reclaim --> &delayed_node->mutex Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&delayed_node->mutex); lock(fs_reclaim); lock(&delayed_node->mutex); rlock(btrfs-tree-01); *** DEADLOCK *** 5 locks held by kworker/u8:12/6861: #0: ffff88801ac89148 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3204 [inline] #0: ffff88801ac89148 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_scheduled_works+0x93b/0x1840 kernel/workqueue.c:3310 #1: ffffc9000369fd00 ((work_completion)(&fs_info->async_reclaim_work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3205 [inline] #1: ffffc9000369fd00 ((work_completion)(&fs_info->async_reclaim_work)){+.+.}-{0:0}, at: process_scheduled_works+0x976/0x1840 kernel/workqueue.c:3310 #2: ffff888034ba2470 (btrfs_trans_num_writers){++++}-{0:0}, at: join_transaction+0x405/0xda0 fs/btrfs/transaction.c:288 #3: ffff888034ba2498 (btrfs_trans_num_extwriters){++++}-{0:0}, at: join_transaction+0x405/0xda0 fs/btrfs/transaction.c:288 #4: ffff888071adc860 (&delayed_node->mutex){+.+.}-{4:4}, at: btrfs_insert_delayed_items fs/btrfs/delayed-inode.c:830 [inline] #4: ffff888071adc860 (&delayed_node->mutex){+.+.}-{4:4}, at: __btrfs_commit_inode_delayed_items+0x1c4/0x24a0 fs/btrfs/delayed-inode.c:1126 stack backtrace: CPU: 0 UID: 0 PID: 6861 Comm: kworker/u8:12 Not tainted 6.12.0-next-20241128-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024 Workqueue: events_unbound btrfs_async_reclaim_metadata_space 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:2074 check_noncircular+0x36a/0x4a0 kernel/locking/lockdep.c:2206 check_prev_add kernel/locking/lockdep.c:3161 [inline] check_prevs_add kernel/locking/lockdep.c:3280 [inline] validate_chain+0x18ef/0x5920 kernel/locking/lockdep.c:3904 __lock_acquire+0x1397/0x2100 kernel/locking/lockdep.c:5226 lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5849 down_read_nested+0xb5/0xa50 kernel/locking/rwsem.c:1649 btrfs_tree_read_lock_nested+0x2f/0x250 fs/btrfs/locking.c:146 btrfs_tree_read_lock fs/btrfs/locking.h:178 [inline] btrfs_read_lock_root_node+0x3f/0xd0 fs/btrfs/locking.c:267 btrfs_search_slot_get_root fs/btrfs/ctree.c:1790 [inline] btrfs_search_slot+0x4f7/0x3150 fs/btrfs/ctree.c:2112 btrfs_insert_empty_items+0x9c/0x1a0 fs/btrfs/ctree.c:4350 btrfs_insert_delayed_item fs/btrfs/delayed-inode.c:758 [inline] btrfs_insert_delayed_items fs/btrfs/delayed-inode.c:836 [inline] __btrfs_commit_inode_delayed_items+0xd5d/0x24a0 fs/btrfs/delayed-inode.c:1126 __btrfs_run_delayed_items+0x213/0x490 fs/btrfs/delayed-inode.c:1171 flush_space+0x24a/0xcf0 fs/btrfs/space-info.c:775 btrfs_async_reclaim_metadata_space+0x113/0x350 fs/btrfs/space-info.c:1105 process_one_work kernel/workqueue.c:3229 [inline] process_scheduled_works+0xa66/0x1840 kernel/workqueue.c:3310 worker_thread+0x870/0xd30 kernel/workqueue.c:3391 kthread+0x2f0/0x390 kernel/kthread.c:389 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244