====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Tainted: G L ------------------------------------------------------ kswapd0/108 is trying to acquire lock: ffff888056f3c4e8 (&ht->mutex){+.+.}-{4:4}, at: rhashtable_free_and_destroy+0x3d/0x9b0 lib/rhashtable.c:1154 but task is already holding lock: ffffffff8e9b0800 (fs_reclaim){+.+.}-{0:0}, at: balance_pgdat+0xb5d/0x1ac0 mm/vmscan.c:7102 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (fs_reclaim){+.+.}-{0:0}: __fs_reclaim_acquire mm/page_alloc.c:4327 [inline] fs_reclaim_acquire+0xc4/0x100 mm/page_alloc.c:4341 might_alloc include/linux/sched/mm.h:317 [inline] slab_pre_alloc_hook mm/slub.c:4520 [inline] slab_alloc_node mm/slub.c:4875 [inline] __do_kmalloc_node mm/slub.c:5294 [inline] __kvmalloc_node_noprof+0xcc/0xa00 mm/slub.c:6828 bucket_table_alloc.isra.0+0x88/0x460 lib/rhashtable.c:186 rhashtable_rehash_alloc+0x68/0x110 lib/rhashtable.c:368 rht_deferred_worker+0x1d9/0x1fd0 lib/rhashtable.c:429 process_one_work+0xa0e/0x1980 kernel/workqueue.c:3302 process_scheduled_works kernel/workqueue.c:3385 [inline] worker_thread+0x5ef/0xe50 kernel/workqueue.c:3466 kthread+0x370/0x450 kernel/kthread.c:436 ret_from_fork+0x72b/0xd50 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 -> #0 (&ht->mutex){+.+.}-{4:4}: check_prev_add kernel/locking/lockdep.c:3165 [inline] check_prevs_add kernel/locking/lockdep.c:3284 [inline] validate_chain kernel/locking/lockdep.c:3908 [inline] __lock_acquire+0x14b8/0x2630 kernel/locking/lockdep.c:5237 lock_acquire kernel/locking/lockdep.c:5868 [inline] lock_acquire+0x1b1/0x370 kernel/locking/lockdep.c:5825 __mutex_lock_common kernel/locking/mutex.c:632 [inline] __mutex_lock+0x1a4/0x1b10 kernel/locking/mutex.c:806 rhashtable_free_and_destroy+0x3d/0x9b0 lib/rhashtable.c:1154 shmem_evict_inode+0x1ae/0xc40 mm/shmem.c:1429 evict+0x3c2/0xad0 fs/inode.c:841 iput_final fs/inode.c:1960 [inline] iput.part.0+0x605/0xf50 fs/inode.c:2009 iput+0x35/0x40 fs/inode.c:1975 dentry_unlink_inode+0x2a1/0x490 fs/dcache.c:467 __dentry_kill+0x1d0/0x600 fs/dcache.c:670 finish_dput+0x76/0x480 fs/dcache.c:879 dput.part.0+0x456/0x570 fs/dcache.c:928 dput+0x1f/0x30 fs/dcache.c:920 ovl_destroy_inode+0x3e/0x190 fs/overlayfs/super.c:217 destroy_inode+0xcb/0x1c0 fs/inode.c:394 evict+0x599/0xad0 fs/inode.c:865 iput_final fs/inode.c:1960 [inline] iput.part.0+0x605/0xf50 fs/inode.c:2009 iput+0x35/0x40 fs/inode.c:1975 dentry_unlink_inode+0x2a1/0x490 fs/dcache.c:467 __dentry_kill+0x1d0/0x600 fs/dcache.c:670 shrink_kill fs/dcache.c:1147 [inline] shrink_dentry_list+0x180/0x5e0 fs/dcache.c:1174 prune_dcache_sb+0xea/0x150 fs/dcache.c:1256 super_cache_scan+0x328/0x550 fs/super.c:223 do_shrink_slab+0x416/0x1240 mm/shrinker.c:440 shrink_slab_memcg mm/shrinker.c:557 [inline] shrink_slab+0xa7d/0x12e0 mm/shrinker.c:635 shrink_one+0x398/0x7f0 mm/vmscan.c:4932 shrink_many mm/vmscan.c:4993 [inline] lru_gen_shrink_node mm/vmscan.c:5071 [inline] shrink_node+0x2673/0x3dc0 mm/vmscan.c:6059 kswapd_shrink_node mm/vmscan.c:6913 [inline] balance_pgdat+0xaaf/0x1ac0 mm/vmscan.c:7089 kswapd+0x557/0xb60 mm/vmscan.c:7362 kthread+0x370/0x450 kernel/kthread.c:436 ret_from_fork+0x72b/0xd50 arch/x86/kernel/process.c:158 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(&ht->mutex); lock(fs_reclaim); lock(&ht->mutex); *** DEADLOCK *** 2 locks held by kswapd0/108: #0: ffffffff8e9b0800 (fs_reclaim){+.+.}-{0:0}, at: balance_pgdat+0xb5d/0x1ac0 mm/vmscan.c:7102 #1: ffff88801347c0d8 (&type->s_umount_key#76){++++}-{4:4}, at: super_trylock_shared fs/super.c:565 [inline] #1: ffff88801347c0d8 (&type->s_umount_key#76){++++}-{4:4}, at: super_cache_scan+0x98/0x550 fs/super.c:198 stack backtrace: CPU: 2 UID: 0 PID: 108 Comm: kswapd0 Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120 print_circular_bug.cold+0x178/0x1c7 kernel/locking/lockdep.c:2043 check_noncircular+0x146/0x160 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 kernel/locking/lockdep.c:3908 [inline] __lock_acquire+0x14b8/0x2630 kernel/locking/lockdep.c:5237 lock_acquire kernel/locking/lockdep.c:5868 [inline] lock_acquire+0x1b1/0x370 kernel/locking/lockdep.c:5825 __mutex_lock_common kernel/locking/mutex.c:632 [inline] __mutex_lock+0x1a4/0x1b10 kernel/locking/mutex.c:806 rhashtable_free_and_destroy+0x3d/0x9b0 lib/rhashtable.c:1154 shmem_evict_inode+0x1ae/0xc40 mm/shmem.c:1429 evict+0x3c2/0xad0 fs/inode.c:841 iput_final fs/inode.c:1960 [inline] iput.part.0+0x605/0xf50 fs/inode.c:2009 iput+0x35/0x40 fs/inode.c:1975 dentry_unlink_inode+0x2a1/0x490 fs/dcache.c:467 __dentry_kill+0x1d0/0x600 fs/dcache.c:670 finish_dput+0x76/0x480 fs/dcache.c:879 dput.part.0+0x456/0x570 fs/dcache.c:928 dput+0x1f/0x30 fs/dcache.c:920 ovl_destroy_inode+0x3e/0x190 fs/overlayfs/super.c:217 destroy_inode+0xcb/0x1c0 fs/inode.c:394 evict+0x599/0xad0 fs/inode.c:865 iput_final fs/inode.c:1960 [inline] iput.part.0+0x605/0xf50 fs/inode.c:2009 iput+0x35/0x40 fs/inode.c:1975 dentry_unlink_inode+0x2a1/0x490 fs/dcache.c:467 __dentry_kill+0x1d0/0x600 fs/dcache.c:670 shrink_kill fs/dcache.c:1147 [inline] shrink_dentry_list+0x180/0x5e0 fs/dcache.c:1174 prune_dcache_sb+0xea/0x150 fs/dcache.c:1256 super_cache_scan+0x328/0x550 fs/super.c:223 do_shrink_slab+0x416/0x1240 mm/shrinker.c:440 shrink_slab_memcg mm/shrinker.c:557 [inline] shrink_slab+0xa7d/0x12e0 mm/shrinker.c:635 shrink_one+0x398/0x7f0 mm/vmscan.c:4932 shrink_many mm/vmscan.c:4993 [inline] lru_gen_shrink_node mm/vmscan.c:5071 [inline] shrink_node+0x2673/0x3dc0 mm/vmscan.c:6059 kswapd_shrink_node mm/vmscan.c:6913 [inline] balance_pgdat+0xaaf/0x1ac0 mm/vmscan.c:7089 kswapd+0x557/0xb60 mm/vmscan.c:7362 kthread+0x370/0x450 kernel/kthread.c:436 ret_from_fork+0x72b/0xd50 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245