Hello, syzbot found the following issue on: HEAD commit: ae3419fbac84 vc_screen: don't clobber return value in vcs_.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=10721d60c80000 kernel config: https://syzkaller.appspot.com/x/.config?x=ff98a3b3c1aed3ab dashboard link: https://syzkaller.appspot.com/bug?extid=bb678557e871cd928756 compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2 Unfortunately, I don't have any reproducer for this issue yet. IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+bb678557e871cd928756@xxxxxxxxxxxxxxxxxxxxxxxxx ====================================================== WARNING: possible circular locking dependency detected 6.2.0-syzkaller-12913-gae3419fbac84 #0 Not tainted ------------------------------------------------------ kswapd0/100 is trying to acquire lock: ffff88801f2f4090 (&sbi->lock){+.+.}-{3:3}, at: reiserfs_write_lock+0x79/0x100 fs/reiserfs/lock.c:27 but task is already holding lock: ffffffff8c8e29e0 (fs_reclaim){+.+.}-{0:0}, at: set_task_reclaim_state mm/vmscan.c:200 [inline] ffffffff8c8e29e0 (fs_reclaim){+.+.}-{0:0}, at: balance_pgdat+0x170/0x1ac0 mm/vmscan.c:7338 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:4716 [inline] fs_reclaim_acquire+0x11d/0x160 mm/page_alloc.c:4730 might_alloc include/linux/sched/mm.h:271 [inline] slab_pre_alloc_hook mm/slab.h:728 [inline] slab_alloc_node mm/slab.c:3241 [inline] slab_alloc mm/slab.c:3266 [inline] __kmem_cache_alloc_lru mm/slab.c:3443 [inline] kmem_cache_alloc_lru+0x3e/0x5d0 mm/slab.c:3459 __d_alloc+0x32/0x980 fs/dcache.c:1769 d_alloc_anon fs/dcache.c:1868 [inline] d_make_root+0x49/0x110 fs/dcache.c:2069 reiserfs_fill_super+0x1301/0x2ea0 fs/reiserfs/super.c:2083 mount_bdev+0x351/0x410 fs/super.c:1371 legacy_get_tree+0x109/0x220 fs/fs_context.c:610 vfs_get_tree+0x8d/0x350 fs/super.c:1501 do_new_mount fs/namespace.c:3042 [inline] path_mount+0x1342/0x1e40 fs/namespace.c:3372 do_mount fs/namespace.c:3385 [inline] __do_sys_mount fs/namespace.c:3594 [inline] __se_sys_mount fs/namespace.c:3571 [inline] __x64_sys_mount+0x283/0x300 fs/namespace.c:3571 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd -> #0 (&sbi->lock){+.+.}-{3:3}: check_prev_add kernel/locking/lockdep.c:3098 [inline] check_prevs_add kernel/locking/lockdep.c:3217 [inline] validate_chain kernel/locking/lockdep.c:3832 [inline] __lock_acquire+0x2ec7/0x5d40 kernel/locking/lockdep.c:5056 lock_acquire kernel/locking/lockdep.c:5669 [inline] lock_acquire+0x1e3/0x670 kernel/locking/lockdep.c:5634 __mutex_lock_common kernel/locking/mutex.c:603 [inline] __mutex_lock+0x12f/0x1350 kernel/locking/mutex.c:747 reiserfs_write_lock+0x79/0x100 fs/reiserfs/lock.c:27 reiserfs_evict_inode+0x30b/0x540 fs/reiserfs/inode.c:55 evict+0x2ed/0x6b0 fs/inode.c:665 iput_final fs/inode.c:1748 [inline] iput.part.0+0x59b/0x8a0 fs/inode.c:1774 iput+0x5c/0x80 fs/inode.c:1764 dentry_unlink_inode+0x2b1/0x460 fs/dcache.c:401 __dentry_kill+0x3c0/0x640 fs/dcache.c:607 shrink_dentry_list+0x12c/0x4f0 fs/dcache.c:1201 prune_dcache_sb+0xeb/0x150 fs/dcache.c:1282 super_cache_scan+0x33a/0x590 fs/super.c:104 do_shrink_slab+0x464/0xd20 mm/vmscan.c:853 shrink_slab_memcg mm/vmscan.c:922 [inline] shrink_slab+0x388/0x660 mm/vmscan.c:1001 shrink_one+0x502/0x810 mm/vmscan.c:5343 shrink_many mm/vmscan.c:5394 [inline] lru_gen_shrink_node mm/vmscan.c:5511 [inline] shrink_node+0x2064/0x35f0 mm/vmscan.c:6459 kswapd_shrink_node mm/vmscan.c:7262 [inline] balance_pgdat+0xa02/0x1ac0 mm/vmscan.c:7452 kswapd+0x70b/0x1000 mm/vmscan.c:7712 kthread+0x2e8/0x3a0 kernel/kthread.c:376 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308 other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(fs_reclaim); lock(&sbi->lock); lock(fs_reclaim); lock(&sbi->lock); *** DEADLOCK *** 3 locks held by kswapd0/100: #0: ffffffff8c8e29e0 (fs_reclaim){+.+.}-{0:0}, at: set_task_reclaim_state mm/vmscan.c:200 [inline] #0: ffffffff8c8e29e0 (fs_reclaim){+.+.}-{0:0}, at: balance_pgdat+0x170/0x1ac0 mm/vmscan.c:7338 #1: ffffffff8c8995d0 (shrinker_rwsem){++++}-{3:3}, at: shrink_slab_memcg mm/vmscan.c:895 [inline] #1: ffffffff8c8995d0 (shrinker_rwsem){++++}-{3:3}, at: shrink_slab+0x2a0/0x660 mm/vmscan.c:1001 #2: ffff88801230a0e0 (&type->s_umount_key#64){++++}-{3:3}, at: trylock_super fs/super.c:414 [inline] #2: ffff88801230a0e0 (&type->s_umount_key#64){++++}-{3:3}, at: super_cache_scan+0x70/0x590 fs/super.c:79 stack backtrace: CPU: 2 PID: 100 Comm: kswapd0 Not tainted 6.2.0-syzkaller-12913-gae3419fbac84 #0 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-2 04/01/2014 Call Trace: <TASK> __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xd9/0x150 lib/dump_stack.c:106 check_noncircular+0x25f/0x2e0 kernel/locking/lockdep.c:2178 check_prev_add kernel/locking/lockdep.c:3098 [inline] check_prevs_add kernel/locking/lockdep.c:3217 [inline] validate_chain kernel/locking/lockdep.c:3832 [inline] __lock_acquire+0x2ec7/0x5d40 kernel/locking/lockdep.c:5056 lock_acquire kernel/locking/lockdep.c:5669 [inline] lock_acquire+0x1e3/0x670 kernel/locking/lockdep.c:5634 __mutex_lock_common kernel/locking/mutex.c:603 [inline] __mutex_lock+0x12f/0x1350 kernel/locking/mutex.c:747 reiserfs_write_lock+0x79/0x100 fs/reiserfs/lock.c:27 reiserfs_evict_inode+0x30b/0x540 fs/reiserfs/inode.c:55 evict+0x2ed/0x6b0 fs/inode.c:665 iput_final fs/inode.c:1748 [inline] iput.part.0+0x59b/0x8a0 fs/inode.c:1774 iput+0x5c/0x80 fs/inode.c:1764 dentry_unlink_inode+0x2b1/0x460 fs/dcache.c:401 __dentry_kill+0x3c0/0x640 fs/dcache.c:607 shrink_dentry_list+0x12c/0x4f0 fs/dcache.c:1201 prune_dcache_sb+0xeb/0x150 fs/dcache.c:1282 super_cache_scan+0x33a/0x590 fs/super.c:104 do_shrink_slab+0x464/0xd20 mm/vmscan.c:853 shrink_slab_memcg mm/vmscan.c:922 [inline] shrink_slab+0x388/0x660 mm/vmscan.c:1001 shrink_one+0x502/0x810 mm/vmscan.c:5343 shrink_many mm/vmscan.c:5394 [inline] lru_gen_shrink_node mm/vmscan.c:5511 [inline] shrink_node+0x2064/0x35f0 mm/vmscan.c:6459 kswapd_shrink_node mm/vmscan.c:7262 [inline] balance_pgdat+0xa02/0x1ac0 mm/vmscan.c:7452 kswapd+0x70b/0x1000 mm/vmscan.c:7712 kthread+0x2e8/0x3a0 kernel/kthread.c:376 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308 </TASK> --- This report is generated by a bot. 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