====================================================== WARNING: possible circular locking dependency detected 6.12.0-rc5-syzkaller-00044-gc1e939a21eb1 #0 Not tainted ------------------------------------------------------ kswapd0/79 is trying to acquire lock: ffff888050101c50 (&bc->lock){+.+.}-{3:3}, at: bch2_btree_cache_scan+0x192/0xd00 fs/bcachefs/btree_cache.c:460 but task is already holding lock: ffffffff8ea37440 (fs_reclaim){+.+.}-{0:0}, at: balance_pgdat mm/vmscan.c:6844 [inline] ffffffff8ea37440 (fs_reclaim){+.+.}-{0:0}, at: kswapd+0xbf1/0x3700 mm/vmscan.c:7226 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (fs_reclaim){+.+.}-{0:0}: lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5825 __fs_reclaim_acquire mm/page_alloc.c:3834 [inline] fs_reclaim_acquire+0x88/0x130 mm/page_alloc.c:3848 might_alloc include/linux/sched/mm.h:318 [inline] slab_pre_alloc_hook mm/slub.c:4036 [inline] slab_alloc_node mm/slub.c:4114 [inline] __do_kmalloc_node mm/slub.c:4263 [inline] __kmalloc_noprof+0xa9/0x400 mm/slub.c:4276 kmalloc_noprof include/linux/slab.h:882 [inline] kzalloc_noprof include/linux/slab.h:1014 [inline] pcpu_mem_zalloc mm/percpu.c:510 [inline] pcpu_alloc_chunk mm/percpu.c:1443 [inline] pcpu_create_chunk+0x57/0xbc0 mm/percpu-vm.c:338 pcpu_balance_populated mm/percpu.c:2075 [inline] pcpu_balance_workfn+0xc4d/0xd40 mm/percpu.c:2212 process_one_work kernel/workqueue.c:3229 [inline] process_scheduled_works+0xa63/0x1850 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 -> #1 (pcpu_alloc_mutex){+.+.}-{3:3}: lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5825 __mutex_lock_common kernel/locking/mutex.c:608 [inline] __mutex_lock+0x136/0xd70 kernel/locking/mutex.c:752 pcpu_alloc_noprof+0x27f/0x16b0 mm/percpu.c:1795 __six_lock_init+0x104/0x150 fs/bcachefs/six.c:869 bch2_btree_lock_init+0x38/0x100 fs/bcachefs/btree_locking.c:12 bch2_btree_node_mem_alloc+0x4f8/0x1340 fs/bcachefs/btree_cache.c:785 __bch2_btree_node_alloc fs/bcachefs/btree_update_interior.c:325 [inline] bch2_btree_reserve_get+0x2df/0x1890 fs/bcachefs/btree_update_interior.c:554 bch2_btree_update_start+0xe56/0x14e0 fs/bcachefs/btree_update_interior.c:1252 bch2_btree_split_leaf+0x123/0x840 fs/bcachefs/btree_update_interior.c:1850 bch2_trans_commit_error+0x212/0x1390 fs/bcachefs/btree_trans_commit.c:942 __bch2_trans_commit+0x7ead/0x93c0 fs/bcachefs/btree_trans_commit.c:1140 wb_flush_one fs/bcachefs/btree_write_buffer.c:183 [inline] bch2_btree_write_buffer_flush_locked+0x2aa8/0x59f0 fs/bcachefs/btree_write_buffer.c:375 btree_write_buffer_flush_seq+0x1a43/0x1bc0 fs/bcachefs/btree_write_buffer.c:510 bch2_btree_write_buffer_journal_flush+0x4e/0x80 fs/bcachefs/btree_write_buffer.c:525 journal_flush_pins+0x5f7/0xb20 fs/bcachefs/journal_reclaim.c:565 journal_flush_done+0x8e/0x260 fs/bcachefs/journal_reclaim.c:819 bch2_journal_flush_pins+0x225/0x3a0 fs/bcachefs/journal_reclaim.c:852 bch2_journal_flush_all_pins fs/bcachefs/journal_reclaim.h:76 [inline] bch2_journal_replay+0x270f/0x2a40 fs/bcachefs/recovery.c:384 bch2_run_recovery_pass+0xf0/0x1e0 fs/bcachefs/recovery_passes.c:185 bch2_run_recovery_passes+0x387/0x870 fs/bcachefs/recovery_passes.c:232 bch2_fs_recovery+0x25cc/0x39c0 fs/bcachefs/recovery.c:862 bch2_fs_start+0x356/0x5b0 fs/bcachefs/super.c:1036 bch2_fs_get_tree+0xd68/0x1710 fs/bcachefs/fs.c:2170 vfs_get_tree+0x90/0x2b0 fs/super.c:1800 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 (&bc->lock){+.+.}-{3:3}: 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+0x1384/0x2050 kernel/locking/lockdep.c:5202 lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5825 __mutex_lock_common kernel/locking/mutex.c:608 [inline] __mutex_lock+0x136/0xd70 kernel/locking/mutex.c:752 bch2_btree_cache_scan+0x192/0xd00 fs/bcachefs/btree_cache.c:460 do_shrink_slab+0x701/0x1160 mm/shrinker.c:435 shrink_slab+0x1093/0x14d0 mm/shrinker.c:662 shrink_one+0x43b/0x850 mm/vmscan.c:4818 shrink_many mm/vmscan.c:4879 [inline] lru_gen_shrink_node mm/vmscan.c:4957 [inline] shrink_node+0x3791/0x3e20 mm/vmscan.c:5937 kswapd_shrink_node mm/vmscan.c:6765 [inline] balance_pgdat mm/vmscan.c:6957 [inline] kswapd+0x1ca3/0x3700 mm/vmscan.c:7226 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: &bc->lock --> pcpu_alloc_mutex --> fs_reclaim Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(fs_reclaim); lock(pcpu_alloc_mutex); lock(fs_reclaim); lock(&bc->lock); *** DEADLOCK *** 1 lock held by kswapd0/79: #0: ffffffff8ea37440 (fs_reclaim){+.+.}-{0:0}, at: balance_pgdat mm/vmscan.c:6844 [inline] #0: ffffffff8ea37440 (fs_reclaim){+.+.}-{0:0}, at: kswapd+0xbf1/0x3700 mm/vmscan.c:7226 stack backtrace: CPU: 0 UID: 0 PID: 79 Comm: kswapd0 Not tainted 6.12.0-rc5-syzkaller-00044-gc1e939a21eb1 #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: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+0x1384/0x2050 kernel/locking/lockdep.c:5202 lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5825 __mutex_lock_common kernel/locking/mutex.c:608 [inline] __mutex_lock+0x136/0xd70 kernel/locking/mutex.c:752 bch2_btree_cache_scan+0x192/0xd00 fs/bcachefs/btree_cache.c:460 do_shrink_slab+0x701/0x1160 mm/shrinker.c:435 shrink_slab+0x1093/0x14d0 mm/shrinker.c:662 shrink_one+0x43b/0x850 mm/vmscan.c:4818 shrink_many mm/vmscan.c:4879 [inline] lru_gen_shrink_node mm/vmscan.c:4957 [inline] shrink_node+0x3791/0x3e20 mm/vmscan.c:5937 kswapd_shrink_node mm/vmscan.c:6765 [inline] balance_pgdat mm/vmscan.c:6957 [inline] kswapd+0x1ca3/0x3700 mm/vmscan.c:7226 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