====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Not tainted ------------------------------------------------------ kswapd0/72 is trying to acquire lock: ffff888042915ad8 (&info->bfs_lock){+.+.}-{4:4}, at: bfs_evict_inode+0x274/0x510 fs/bfs/inode.c:183 but task is already holding lock: ffffffff8de44f40 (fs_reclaim){+.+.}-{0:0}, at: balance_pgdat mm/vmscan.c:7015 [inline] ffffffff8de44f40 (fs_reclaim){+.+.}-{0:0}, at: kswapd+0x951/0x2800 mm/vmscan.c:7389 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (fs_reclaim){+.+.}-{0:0}: lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868 __fs_reclaim_acquire mm/page_alloc.c:4269 [inline] fs_reclaim_acquire+0x72/0x100 mm/page_alloc.c:4283 might_alloc include/linux/sched/mm.h:318 [inline] slab_pre_alloc_hook mm/slub.c:4897 [inline] slab_alloc_node mm/slub.c:5221 [inline] kmem_cache_alloc_lru_noprof+0x4a/0x6d0 mm/slub.c:5264 bfs_alloc_inode+0x28/0x40 fs/bfs/inode.c:240 alloc_inode+0x67/0x1b0 fs/inode.c:346 iget_locked+0x106/0x580 fs/inode.c:1445 bfs_iget+0x28/0xaa0 fs/bfs/inode.c:42 bfs_lookup+0x150/0x1d0 fs/bfs/dir.c:141 lookup_one_qstr_excl+0x12e/0x360 fs/namei.c:1705 do_renameat2+0x3dd/0xa50 fs/namei.c:5317 __do_sys_rename fs/namei.c:5411 [inline] __se_sys_rename fs/namei.c:5409 [inline] __x64_sys_rename+0x82/0x90 fs/namei.c:5409 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #0 (&info->bfs_lock){+.+.}-{4:4}: check_prev_add kernel/locking/lockdep.c:3165 [inline] check_prevs_add kernel/locking/lockdep.c:3284 [inline] validate_chain+0xb9b/0x2140 kernel/locking/lockdep.c:3908 __lock_acquire+0xab9/0xd20 kernel/locking/lockdep.c:5237 lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868 __mutex_lock_common kernel/locking/mutex.c:598 [inline] __mutex_lock+0x187/0x1350 kernel/locking/mutex.c:760 bfs_evict_inode+0x274/0x510 fs/bfs/inode.c:183 evict+0x501/0x9c0 fs/inode.c:810 __dentry_kill+0x209/0x660 fs/dcache.c:669 shrink_kill+0xa9/0x2c0 fs/dcache.c:1114 shrink_dentry_list+0x2e0/0x5e0 fs/dcache.c:1141 prune_dcache_sb+0x10e/0x180 fs/dcache.c:1222 super_cache_scan+0x369/0x4b0 fs/super.c:222 do_shrink_slab+0x6ef/0x1110 mm/shrinker.c:437 shrink_slab_memcg mm/shrinker.c:550 [inline] shrink_slab+0x7ef/0x10d0 mm/shrinker.c:628 shrink_one+0x28a/0x7c0 mm/vmscan.c:4955 shrink_many mm/vmscan.c:5016 [inline] lru_gen_shrink_node mm/vmscan.c:5094 [inline] shrink_node+0x315d/0x3780 mm/vmscan.c:6081 kswapd_shrink_node mm/vmscan.c:6941 [inline] balance_pgdat mm/vmscan.c:7124 [inline] kswapd+0x147c/0x2800 mm/vmscan.c:7389 kthread+0x70e/0x8a0 kernel/kthread.c:463 ret_from_fork+0x436/0x7d0 arch/x86/kernel/process.c:148 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(fs_reclaim); lock(&info->bfs_lock); lock(fs_reclaim); lock(&info->bfs_lock); *** DEADLOCK *** 2 locks held by kswapd0/72: #0: ffffffff8de44f40 (fs_reclaim){+.+.}-{0:0}, at: balance_pgdat mm/vmscan.c:7015 [inline] #0: ffffffff8de44f40 (fs_reclaim){+.+.}-{0:0}, at: kswapd+0x951/0x2800 mm/vmscan.c:7389 #1: ffff888010fbc0e0 (&type->s_umount_key#51){++++}-{4:4}, at: super_trylock_shared fs/super.c:562 [inline] #1: ffff888010fbc0e0 (&type->s_umount_key#51){++++}-{4:4}, at: super_cache_scan+0x91/0x4b0 fs/super.c:197 stack backtrace: CPU: 0 UID: 0 PID: 72 Comm: kswapd0 Not tainted syzkaller #0 PREEMPT(full) 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_lvl+0x189/0x250 lib/dump_stack.c:120 print_circular_bug+0x2ee/0x310 kernel/locking/lockdep.c:2043 check_noncircular+0x134/0x160 kernel/locking/lockdep.c:2175 check_prev_add kernel/locking/lockdep.c:3165 [inline] check_prevs_add kernel/locking/lockdep.c:3284 [inline] validate_chain+0xb9b/0x2140 kernel/locking/lockdep.c:3908 __lock_acquire+0xab9/0xd20 kernel/locking/lockdep.c:5237 lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868 __mutex_lock_common kernel/locking/mutex.c:598 [inline] __mutex_lock+0x187/0x1350 kernel/locking/mutex.c:760 bfs_evict_inode+0x274/0x510 fs/bfs/inode.c:183 evict+0x501/0x9c0 fs/inode.c:810 __dentry_kill+0x209/0x660 fs/dcache.c:669 shrink_kill+0xa9/0x2c0 fs/dcache.c:1114 shrink_dentry_list+0x2e0/0x5e0 fs/dcache.c:1141 prune_dcache_sb+0x10e/0x180 fs/dcache.c:1222 super_cache_scan+0x369/0x4b0 fs/super.c:222 do_shrink_slab+0x6ef/0x1110 mm/shrinker.c:437 shrink_slab_memcg mm/shrinker.c:550 [inline] shrink_slab+0x7ef/0x10d0 mm/shrinker.c:628 shrink_one+0x28a/0x7c0 mm/vmscan.c:4955 shrink_many mm/vmscan.c:5016 [inline] lru_gen_shrink_node mm/vmscan.c:5094 [inline] shrink_node+0x315d/0x3780 mm/vmscan.c:6081 kswapd_shrink_node mm/vmscan.c:6941 [inline] balance_pgdat mm/vmscan.c:7124 [inline] kswapd+0x147c/0x2800 mm/vmscan.c:7389 kthread+0x70e/0x8a0 kernel/kthread.c:463 ret_from_fork+0x436/0x7d0 arch/x86/kernel/process.c:148 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245