[syzbot] [jffs2?] possible deadlock in jffs2_do_clear_inode

[syzbot]

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+88a60d...@syzkaller.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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