====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Not tainted ------------------------------------------------------ kswapd0/75 is trying to acquire lock: ffff8880131ab760 (&f->sem){+.+.}-{4:4}, at: jffs2_do_clear_inode+0x62/0x390 fs/jffs2/readinode.c:1419 but task is already holding lock: ffffffff8ec86cc0 (fs_reclaim){+.+.}-{0:0}, at: balance_pgdat mm/vmscan.c:7084 [inline] ffffffff8ec86cc0 (fs_reclaim){+.+.}-{0:0}, at: kswapd+0x9b6/0x31c0 mm/vmscan.c:7462 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:4329 [inline] fs_reclaim_acquire+0x71/0x100 mm/page_alloc.c:4343 might_alloc include/linux/sched/mm.h:317 [inline] slab_pre_alloc_hook mm/slub.c:4537 [inline] slab_alloc_node mm/slub.c:4897 [inline] kmem_cache_alloc_noprof+0x64/0x5f0 mm/slub.c:4931 jffs2_do_read_inode+0x33f/0x6a0 fs/jffs2/readinode.c:1372 jffs2_iget+0x228/0xcc0 fs/jffs2/fs.c:277 jffs2_do_fill_super+0x59d/0xc50 fs/jffs2/fs.c:578 mtd_get_sb+0x18a/0x410 drivers/mtd/mtdsuper.c:57 mtd_get_sb_by_nr drivers/mtd/mtdsuper.c:88 [inline] get_tree_mtd+0x4bd/0x7d0 drivers/mtd/mtdsuper.c:158 vfs_get_tree+0x92/0x2a0 fs/super.c:1700 fc_mount fs/namespace.c:1198 [inline] do_new_mount_fc fs/namespace.c:3765 [inline] do_new_mount+0x319/0xdc0 fs/namespace.c:3841 do_mount fs/namespace.c:4174 [inline] __do_sys_mount fs/namespace.c:4390 [inline] __se_sys_mount+0x31d/0x420 fs/namespace.c:4367 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #0 (&f->sem){+.+.}-{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+0x1520/0x2cf0 kernel/locking/lockdep.c:5237 lock_acquire+0x106/0x350 kernel/locking/lockdep.c:5868 __mutex_lock_common kernel/locking/mutex.c:646 [inline] __mutex_lock+0x19d/0x1550 kernel/locking/mutex.c:821 jffs2_do_clear_inode+0x62/0x390 fs/jffs2/readinode.c:1419 evict+0x624/0xb50 fs/inode.c:825 dispose_list fs/inode.c:867 [inline] prune_icache_sb+0x223/0x2d0 fs/inode.c:1014 super_cache_scan+0x38d/0x4a0 fs/super.c:225 do_shrink_slab+0x6d0/0x10e0 mm/shrinker.c:443 shrink_slab_memcg mm/shrinker.c:560 [inline] shrink_slab+0x838/0x1220 mm/shrinker.c:638 shrink_one+0x2a2/0x730 mm/vmscan.c:5026 shrink_many mm/vmscan.c:5087 [inline] lru_gen_shrink_node mm/vmscan.c:5165 [inline] shrink_node+0x3303/0x3b60 mm/vmscan.c:6154 kswapd_shrink_node mm/vmscan.c:7008 [inline] balance_pgdat mm/vmscan.c:7186 [inline] kswapd+0x17b6/0x31c0 mm/vmscan.c:7462 kthread+0x388/0x470 kernel/kthread.c:436 ret_from_fork+0x514/0xb70 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 *** 2 locks held by kswapd0/75: #0: ffffffff8ec86cc0 (fs_reclaim){+.+.}-{0:0}, at: balance_pgdat mm/vmscan.c:7084 [inline] #0: ffffffff8ec86cc0 (fs_reclaim){+.+.}-{0:0}, at: kswapd+0x9b6/0x31c0 mm/vmscan.c:7462 #1: ffff8880372f00d8 (&type->s_umount_key#54){.+.+}-{4:4}, at: super_trylock_shared fs/super.c:566 [inline] #1: ffff8880372f00d8 (&type->s_umount_key#54){.+.+}-{4:4}, at: super_cache_scan+0x91/0x4a0 fs/super.c:198 stack backtrace: CPU: 0 UID: 0 PID: 75 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 04/01/2014 Call Trace: dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120 print_circular_bug+0x2e1/0x300 kernel/locking/lockdep.c:2043 check_noncircular+0x12e/0x150 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+0x1520/0x2cf0 kernel/locking/lockdep.c:5237 lock_acquire+0x106/0x350 kernel/locking/lockdep.c:5868 __mutex_lock_common kernel/locking/mutex.c:646 [inline] __mutex_lock+0x19d/0x1550 kernel/locking/mutex.c:821 jffs2_do_clear_inode+0x62/0x390 fs/jffs2/readinode.c:1419 evict+0x624/0xb50 fs/inode.c:825 dispose_list fs/inode.c:867 [inline] prune_icache_sb+0x223/0x2d0 fs/inode.c:1014 super_cache_scan+0x38d/0x4a0 fs/super.c:225 do_shrink_slab+0x6d0/0x10e0 mm/shrinker.c:443 shrink_slab_memcg mm/shrinker.c:560 [inline] shrink_slab+0x838/0x1220 mm/shrinker.c:638 shrink_one+0x2a2/0x730 mm/vmscan.c:5026 shrink_many mm/vmscan.c:5087 [inline] lru_gen_shrink_node mm/vmscan.c:5165 [inline] shrink_node+0x3303/0x3b60 mm/vmscan.c:6154 kswapd_shrink_node mm/vmscan.c:7008 [inline] balance_pgdat mm/vmscan.c:7186 [inline] kswapd+0x17b6/0x31c0 mm/vmscan.c:7462 kthread+0x388/0x470 kernel/kthread.c:436 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245