====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Tainted: G L ------------------------------------------------------ kswapd0/115 is trying to acquire lock: ffff8880143f7960 (&f->sem){+.+.}-{4:4}, at: jffs2_do_clear_inode+0x5a/0x470 fs/jffs2/readinode.c:1419 but task is already holding lock: ffffffff901d7d80 (fs_reclaim){+.+.}-{0:0}, at: balance_pgdat+0xb4a/0x1e60 mm/vmscan.c:7442 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (fs_reclaim){+.+.}-{0:0}: lock_acquire kernel/locking/lockdep.c:5942 [inline] lock_acquire+0x1d1/0x380 kernel/locking/lockdep.c:5899 __fs_reclaim_acquire mm/page_alloc.c:4365 [inline] fs_reclaim_acquire+0xc4/0x100 mm/page_alloc.c:4379 might_alloc include/linux/sched/mm.h:316 [inline] slab_pre_alloc_hook mm/slub.c:4673 [inline] slab_alloc_node mm/slub.c:5011 [inline] kmem_cache_alloc_noprof+0x63/0x6a0 mm/slub.c:5047 jffs2_do_read_inode+0x307/0x520 fs/jffs2/readinode.c:1372 jffs2_iget+0x32b/0xe30 fs/jffs2/fs.c:277 jffs2_do_fill_super+0x44b/0xa60 fs/jffs2/fs.c:578 jffs2_fill_super+0x283/0x370 fs/jffs2/super.c:290 mtd_get_sb+0x2f9/0x4d0 drivers/mtd/mtdsuper.c:59 mtd_get_sb_by_nr drivers/mtd/mtdsuper.c:90 [inline] get_tree_mtd+0x6f9/0x8a0 drivers/mtd/mtdsuper.c:143 vfs_get_tree+0x92/0x320 fs/super.c:1881 fc_mount fs/namespace.c:1282 [inline] do_new_mount_fc fs/namespace.c:3910 [inline] do_new_mount fs/namespace.c:3986 [inline] path_mount+0x7d0/0x2850 fs/namespace.c:4337 do_mount fs/namespace.c:4350 [inline] __do_sys_mount fs/namespace.c:4565 [inline] __se_sys_mount fs/namespace.c:4542 [inline] __ia32_sys_mount+0x292/0x310 fs/namespace.c:4542 do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:79 [inline] __do_fast_syscall_32+0x14b/0x8c0 arch/x86/entry/syscall_32.c:282 do_fast_syscall_32+0x32/0x70 arch/x86/entry/syscall_32.c:307 entry_SYSENTER_compat_after_hwframe+0x84/0x8e -> #0 (&f->sem){+.+.}-{4:4}: check_prev_add+0xeb/0xe60 kernel/locking/lockdep.c:3209 check_prevs_add kernel/locking/lockdep.c:3328 [inline] validate_chain kernel/locking/lockdep.c:3952 [inline] __lock_acquire+0x1528/0x1f40 kernel/locking/lockdep.c:5288 lock_acquire kernel/locking/lockdep.c:5942 [inline] lock_acquire+0x1d1/0x380 kernel/locking/lockdep.c:5899 __mutex_lock_common kernel/locking/mutex.c:646 [inline] __mutex_lock+0x19f/0x1c10 kernel/locking/mutex.c:821 jffs2_do_clear_inode+0x5a/0x470 fs/jffs2/readinode.c:1419 evict+0x3c2/0xad0 fs/inode.c:821 dispose_list+0x117/0x1e0 fs/inode.c:863 prune_icache_sb+0xea/0x150 fs/inode.c:1021 super_cache_scan+0x37c/0x560 fs/super.c:227 do_shrink_slab+0x411/0x1200 mm/shrinker.c:452 shrink_slab_memcg mm/shrinker.c:569 [inline] shrink_slab+0xa78/0x12d0 mm/shrinker.c:647 shrink_one+0x3d3/0x870 mm/vmscan.c:5320 shrink_many mm/vmscan.c:5381 [inline] lru_gen_shrink_node mm/vmscan.c:5459 [inline] shrink_node+0x2a61/0x4410 mm/vmscan.c:6465 kswapd_shrink_node mm/vmscan.c:7258 [inline] balance_pgdat+0xa9e/0x1e60 mm/vmscan.c:7429 kswapd+0x556/0xb50 mm/vmscan.c:7705 kthread+0x373/0x450 kernel/kthread.c:436 ret_from_fork+0x730/0xd60 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(&f->sem); lock(fs_reclaim); lock(&f->sem); *** DEADLOCK *** locks held by kswapd0/115: 2, last CPU#3: #0: ffffffff901d7d80 (fs_reclaim){+.+.}-{0:0}, at: balance_pgdat+0xb4a/0x1e60 mm/vmscan.c:7442 #1: ffff8880714f4100 (&type->s_umount_key#54){++++}-{4:4}, at: super_trylock_shared fs/super.c:642 [inline] #1: ffff8880714f4100 (&type->s_umount_key#54){++++}-{4:4}, at: super_cache_scan+0x9b/0x560 fs/super.c:200 stack backtrace: CPU: 3 UID: 0 PID: 115 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+0x178/0x1be kernel/locking/lockdep.c:2087 check_noncircular+0x146/0x160 kernel/locking/lockdep.c:2219 check_prev_add+0xeb/0xe60 kernel/locking/lockdep.c:3209 check_prevs_add kernel/locking/lockdep.c:3328 [inline] validate_chain kernel/locking/lockdep.c:3952 [inline] __lock_acquire+0x1528/0x1f40 kernel/locking/lockdep.c:5288 lock_acquire kernel/locking/lockdep.c:5942 [inline] lock_acquire+0x1d1/0x380 kernel/locking/lockdep.c:5899 __mutex_lock_common kernel/locking/mutex.c:646 [inline] __mutex_lock+0x19f/0x1c10 kernel/locking/mutex.c:821 jffs2_do_clear_inode+0x5a/0x470 fs/jffs2/readinode.c:1419 evict+0x3c2/0xad0 fs/inode.c:821 dispose_list+0x117/0x1e0 fs/inode.c:863 prune_icache_sb+0xea/0x150 fs/inode.c:1021 super_cache_scan+0x37c/0x560 fs/super.c:227 do_shrink_slab+0x411/0x1200 mm/shrinker.c:452 shrink_slab_memcg mm/shrinker.c:569 [inline] shrink_slab+0xa78/0x12d0 mm/shrinker.c:647 shrink_one+0x3d3/0x870 mm/vmscan.c:5320 shrink_many mm/vmscan.c:5381 [inline] lru_gen_shrink_node mm/vmscan.c:5459 [inline] shrink_node+0x2a61/0x4410 mm/vmscan.c:6465 kswapd_shrink_node mm/vmscan.c:7258 [inline] balance_pgdat+0xa9e/0x1e60 mm/vmscan.c:7429 kswapd+0x556/0xb50 mm/vmscan.c:7705 kthread+0x373/0x450 kernel/kthread.c:436 ret_from_fork+0x730/0xd60 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245