====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Tainted: G L ------------------------------------------------------ kswapd0/114 is trying to acquire lock: ffff88802f7290e0 (&f->sem){+.+.}-{4:4}, at: jffs2_do_clear_inode+0x5a/0x470 fs/jffs2/readinode.c:1419 but task is already holding lock: ffffffff8ffcb2c0 (fs_reclaim){+.+.}-{0:0}, at: balance_pgdat+0xbce/0x1f00 mm/vmscan.c:7292 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:4375 [inline] fs_reclaim_acquire+0xc4/0x100 mm/page_alloc.c:4389 might_alloc include/linux/sched/mm.h:316 [inline] slab_pre_alloc_hook mm/slub.c:4636 [inline] slab_alloc_node mm/slub.c:4974 [inline] kmem_cache_alloc_noprof+0x63/0x6a0 mm/slub.c:5010 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/0xa50 fs/jffs2/fs.c:578 jffs2_fill_super+0x283/0x370 fs/jffs2/super.c:290 mtd_get_sb+0x2f0/0x4c0 drivers/mtd/mtdsuper.c:57 mtd_get_sb_by_nr drivers/mtd/mtdsuper.c:88 [inline] get_tree_mtd+0x6f9/0x8a0 drivers/mtd/mtdsuper.c:141 vfs_get_tree+0x92/0x320 fs/super.c:1943 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:4566 [inline] __se_sys_mount fs/namespace.c:4543 [inline] __x64_sys_mount+0x293/0x310 fs/namespace.c:4543 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline] do_syscall_64+0x123/0x790 arch/x86/entry/syscall_64.c:84 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #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+0x1a4/0x1c20 kernel/locking/mutex.c:821 jffs2_do_clear_inode+0x5a/0x470 fs/jffs2/readinode.c:1419 evict+0x3c2/0xad0 fs/inode.c:822 dispose_list+0x117/0x1e0 fs/inode.c:864 prune_icache_sb+0xea/0x150 fs/inode.c:1010 super_cache_scan+0x376/0x550 fs/super.c:227 do_shrink_slab+0x416/0x1200 mm/shrinker.c:445 shrink_slab_memcg mm/shrinker.c:562 [inline] shrink_slab+0xa82/0x12e0 mm/shrinker.c:640 shrink_one+0x398/0x850 mm/vmscan.c:5119 shrink_many mm/vmscan.c:5180 [inline] lru_gen_shrink_node mm/vmscan.c:5258 [inline] shrink_node+0x2b20/0x4320 mm/vmscan.c:6247 kswapd_shrink_node mm/vmscan.c:7101 [inline] balance_pgdat+0xb20/0x1f00 mm/vmscan.c:7279 kswapd+0x556/0xb50 mm/vmscan.c:7555 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 kswapd0/114: 2, last CPU#3: #0: ffffffff8ffcb2c0 (fs_reclaim){+.+.}-{0:0}, at: balance_pgdat+0xbce/0x1f00 mm/vmscan.c:7292 #1: ffff88803ab640e8 (&type->s_umount_key#76){++++}-{4:4}, at: super_trylock_shared fs/super.c:670 [inline] #1: ffff88803ab640e8 (&type->s_umount_key#76){++++}-{4:4}, at: super_cache_scan+0x9b/0x550 fs/super.c:200 stack backtrace: CPU: 3 UID: 0 PID: 114 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+0x1a4/0x1c20 kernel/locking/mutex.c:821 jffs2_do_clear_inode+0x5a/0x470 fs/jffs2/readinode.c:1419 evict+0x3c2/0xad0 fs/inode.c:822 dispose_list+0x117/0x1e0 fs/inode.c:864 prune_icache_sb+0xea/0x150 fs/inode.c:1010 super_cache_scan+0x376/0x550 fs/super.c:227 do_shrink_slab+0x416/0x1200 mm/shrinker.c:445 shrink_slab_memcg mm/shrinker.c:562 [inline] shrink_slab+0xa82/0x12e0 mm/shrinker.c:640 shrink_one+0x398/0x850 mm/vmscan.c:5119 shrink_many mm/vmscan.c:5180 [inline] lru_gen_shrink_node mm/vmscan.c:5258 [inline] shrink_node+0x2b20/0x4320 mm/vmscan.c:6247 kswapd_shrink_node mm/vmscan.c:7101 [inline] balance_pgdat+0xb20/0x1f00 mm/vmscan.c:7279 kswapd+0x556/0xb50 mm/vmscan.c:7555 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