Message-ID: <000000000000ecf68e0615b7a737@google.com>
Date: Tue, 09 Apr 2024 22:53:20 -0700
From: syzbot <syzbot+88a60d3f927e2460d4ac@...kaller.appspotmail.com>
To: dwmw2@...radead.org, linux-fsdevel@...r.kernel.org, 
	linux-kernel@...r.kernel.org, linux-mtd@...ts.infradead.org, richard@....at, 
	syzkaller-bugs@...glegroups.com
Subject: [syzbot] [jffs2?] possible deadlock in jffs2_do_clear_inode

Hello,

syzbot found the following issue on:

HEAD commit:    e8b0ccb2a787 Merge tag '9p-for-6.9-rc3' of https://github...
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=12f9ee15180000
kernel config:  https://syzkaller.appspot.com/x/.config?x=8c2c72b264636e25
dashboard link: https://syzkaller.appspot.com/bug?extid=88a60d3f927e2460d4ac
compiler:       gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
userspace arch: i386

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/7bc7510fe41f/non_bootable_disk-e8b0ccb2.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/36cfb6ee2b7e/vmlinux-e8b0ccb2.xz
kernel image: https://storage.googleapis.com/syzbot-assets/86b45977fab6/bzImage-e8b0ccb2.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+88a60d3f927e2460d4ac@...kaller.appspotmail.com

======================================================
WARNING: possible circular locking dependency detected
6.9.0-rc2-syzkaller-00207-ge8b0ccb2a787 #0 Not tainted
------------------------------------------------------
kswapd1/112 is trying to acquire lock:
ffff888064068640 (&f->sem){+.+.}-{3:3}, at: jffs2_do_clear_inode+0x5a/0x470 fs/jffs2/readinode.c:1419

but task is already holding lock:
ffffffff8d939440 (fs_reclaim){+.+.}-{0:0}, at: balance_pgdat+0x166/0x1a10 mm/vmscan.c:6782

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:3698 [inline]
       fs_reclaim_acquire+0x102/0x160 mm/page_alloc.c:3712
       might_alloc include/linux/sched/mm.h:312 [inline]
       slab_pre_alloc_hook mm/slub.c:3746 [inline]
       slab_alloc_node mm/slub.c:3827 [inline]
       kmem_cache_alloc+0x4f/0x320 mm/slub.c:3852
       jffs2_do_read_inode+0x3e8/0x670 fs/jffs2/readinode.c:1372
       jffs2_iget+0x2c3/0xed0 fs/jffs2/fs.c:277
       jffs2_do_fill_super+0x44b/0xa60 fs/jffs2/fs.c:577
       jffs2_fill_super+0x283/0x370 fs/jffs2/super.c:289
       mtd_get_sb+0x2ce/0x490 drivers/mtd/mtdsuper.c:57
       mtd_get_sb_by_nr drivers/mtd/mtdsuper.c:88 [inline]
       get_tree_mtd+0x6ce/0x860 drivers/mtd/mtdsuper.c:141
       vfs_get_tree+0x8f/0x380 fs/super.c:1779
       do_new_mount fs/namespace.c:3352 [inline]
       path_mount+0x6e1/0x1f10 fs/namespace.c:3679
       do_mount fs/namespace.c:3692 [inline]
       __do_sys_mount fs/namespace.c:3898 [inline]
       __se_sys_mount fs/namespace.c:3875 [inline]
       __ia32_sys_mount+0x295/0x320 fs/namespace.c:3875
       do_syscall_32_irqs_on arch/x86/entry/common.c:165 [inline]
       __do_fast_syscall_32+0x7a/0x120 arch/x86/entry/common.c:321
       do_fast_syscall_32+0x32/0x80 arch/x86/entry/common.c:346
       entry_SYSENTER_compat_after_hwframe+0x7f/0x89

-> #0 (&f->sem){+.+.}-{3:3}:
       check_prev_add kernel/locking/lockdep.c:3134 [inline]
       check_prevs_add kernel/locking/lockdep.c:3253 [inline]
       validate_chain kernel/locking/lockdep.c:3869 [inline]
       __lock_acquire+0x2478/0x3b30 kernel/locking/lockdep.c:5137
       lock_acquire kernel/locking/lockdep.c:5754 [inline]
       lock_acquire+0x1b1/0x560 kernel/locking/lockdep.c:5719
       __mutex_lock_common kernel/locking/mutex.c:608 [inline]
       __mutex_lock+0x175/0x9c0 kernel/locking/mutex.c:752
       jffs2_do_clear_inode+0x5a/0x470 fs/jffs2/readinode.c:1419
       evict+0x2ed/0x6c0 fs/inode.c:667
       dispose_list+0x117/0x1e0 fs/inode.c:700
       prune_icache_sb+0xeb/0x150 fs/inode.c:885
       super_cache_scan+0x375/0x550 fs/super.c:223
       do_shrink_slab+0x44f/0x11c0 mm/shrinker.c:435
       shrink_slab_memcg mm/shrinker.c:548 [inline]
       shrink_slab+0xa87/0x1310 mm/shrinker.c:626
       shrink_one+0x493/0x7c0 mm/vmscan.c:4774
       shrink_many mm/vmscan.c:4835 [inline]
       lru_gen_shrink_node+0x89f/0x1750 mm/vmscan.c:4935
       shrink_node mm/vmscan.c:5894 [inline]
       kswapd_shrink_node mm/vmscan.c:6704 [inline]
       balance_pgdat+0x10d1/0x1a10 mm/vmscan.c:6895
       kswapd+0x5ea/0xbf0 mm/vmscan.c:7164
       kthread+0x2c1/0x3a0 kernel/kthread.c:388
       ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
       ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:243

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 kswapd1/112:
 #0: ffffffff8d939440 (fs_reclaim){+.+.}-{0:0}, at: balance_pgdat+0x166/0x1a10 mm/vmscan.c:6782
 #1: ffff88805e1aa0e0 (&type->s_umount_key#88){++++}-{3:3}, at: super_trylock_shared fs/super.c:561 [inline]
 #1: ffff88805e1aa0e0 (&type->s_umount_key#88){++++}-{3:3}, at: super_cache_scan+0x96/0x550 fs/super.c:196

stack backtrace:
CPU: 1 PID: 112 Comm: kswapd1 Not tainted 6.9.0-rc2-syzkaller-00207-ge8b0ccb2a787 #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:114
 check_noncircular+0x31a/0x400 kernel/locking/lockdep.c:2187
 check_prev_add kernel/locking/lockdep.c:3134 [inline]
 check_prevs_add kernel/locking/lockdep.c:3253 [inline]
 validate_chain kernel/locking/lockdep.c:3869 [inline]
 __lock_acquire+0x2478/0x3b30 kernel/locking/lockdep.c:5137
 lock_acquire kernel/locking/lockdep.c:5754 [inline]
 lock_acquire+0x1b1/0x560 kernel/locking/lockdep.c:5719
 __mutex_lock_common kernel/locking/mutex.c:608 [inline]
 __mutex_lock+0x175/0x9c0 kernel/locking/mutex.c:752
 jffs2_do_clear_inode+0x5a/0x470 fs/jffs2/readinode.c:1419
 evict+0x2ed/0x6c0 fs/inode.c:667
 dispose_list+0x117/0x1e0 fs/inode.c:700
 prune_icache_sb+0xeb/0x150 fs/inode.c:885
 super_cache_scan+0x375/0x550 fs/super.c:223
 do_shrink_slab+0x44f/0x11c0 mm/shrinker.c:435
 shrink_slab_memcg mm/shrinker.c:548 [inline]
 shrink_slab+0xa87/0x1310 mm/shrinker.c:626
 shrink_one+0x493/0x7c0 mm/vmscan.c:4774
 shrink_many mm/vmscan.c:4835 [inline]
 lru_gen_shrink_node+0x89f/0x1750 mm/vmscan.c:4935
 shrink_node mm/vmscan.c:5894 [inline]
 kswapd_shrink_node mm/vmscan.c:6704 [inline]
 balance_pgdat+0x10d1/0x1a10 mm/vmscan.c:6895
 kswapd+0x5ea/0xbf0 mm/vmscan.c:7164
 kthread+0x2c1/0x3a0 kernel/kthread.c:388
 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:243
 </TASK>


---
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