[syzbot] [jffs2?] possible deadlock in jffs2_do_clear_inode (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 848acc8ffe1b Merge tag 'fsverity-for-linus' of git://git.k..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=13a07e32580000
kernel config: https://syzkaller.appspot.com/x/.config?x=4e38b15c29e6a1d9
dashboard link: https://syzkaller.appspot.com/bug?extid=743079a09058321247d8
compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/9bf3ffd710de/disk-848acc8f.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/770c0a63a80c/vmlinux-848acc8f.xz
kernel image: https://storage.googleapis.com/syzbot-assets/c54f9393cb03/bzImage-848acc8f.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+743079...@syzkaller.appspotmail.com

======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Tainted: G N
------------------------------------------------------
syz.3.73/6195 is trying to acquire lock:
ffff88805432b1e0 (&f->sem){+.+.}-{4:4}, at: jffs2_do_clear_inode+0x62/0x390 fs/jffs2/readinode.c:1419

but task is already holding lock:
ffffffff8ec848e0 (fs_reclaim){+.+.}-{0:0}, at: __perform_reclaim mm/page_alloc.c:4402 [inline]
ffffffff8ec848e0 (fs_reclaim){+.+.}-{0:0}, at: __alloc_pages_direct_reclaim+0xbd/0x310 mm/page_alloc.c:4427

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
shrink_zones mm/vmscan.c:6410 [inline]
do_try_to_free_pages+0x6a3/0x1990 mm/vmscan.c:6472
try_to_free_pages+0x90a/0xe50 mm/vmscan.c:6711
__perform_reclaim mm/page_alloc.c:4405 [inline]
__alloc_pages_direct_reclaim+0x148/0x310 mm/page_alloc.c:4427
__alloc_pages_slowpath+0x59d/0xcc0 mm/page_alloc.c:4876
__alloc_frozen_pages_noprof+0x31f/0x380 mm/page_alloc.c:5317
alloc_pages_mpol+0x212/0x380 mm/mempolicy.c:2490
alloc_frozen_pages_noprof mm/mempolicy.c:2561 [inline]
alloc_pages_noprof+0xac/0x2a0 mm/mempolicy.c:2581
alloc_image_page+0x23/0x130 kernel/power/snapshot.c:231
preallocate_image_pages kernel/power/snapshot.c:1654 [inline]
preallocate_image_memory+0x76/0x140 kernel/power/snapshot.c:1681
hibernate_preallocate_memory+0x43c/0x750 kernel/power/snapshot.c:1960
hibernation_snapshot+0x126/0x3d0 kernel/power/hibernate.c:430
hibernate+0x28f/0x680 kernel/power/hibernate.c:811
state_store+0x234/0x290 kernel/power/main.c:821
kernfs_fop_write_iter+0x3a4/0x540 fs/kernfs/file.c:345
new_sync_write fs/read_write.c:595 [inline]
vfs_write+0x612/0xba0 fs/read_write.c:687
ksys_write+0x150/0x270 fs/read_write.c:739
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

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 ***

9 locks held by syz.3.73/6195:
#0: ffff88807a0a70b0 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x246/0x320 fs/file.c:1259
#1: ffff888034304450 (sb_writers#7){.+.+}-{0:0}, at: file_start_write include/linux/fs.h:2733 [inline]
#1: ffff888034304450 (sb_writers#7){.+.+}-{0:0}, at: vfs_write+0x22b/0xba0 fs/read_write.c:683
#2: ffff88805386dc80 (&of->mutex){+.+.}-{4:4}, at: kernfs_fop_write_iter+0x1d8/0x540 fs/kernfs/file.c:336
#3: ffff88801f28d968 (kn->active#59){.+.+}-{0:0}, at: kernfs_get_active_of fs/kernfs/file.c:73 [inline]
#3: ffff88801f28d968 (kn->active#59){.+.+}-{0:0}, at: kernfs_fop_write_iter+0x22b/0x540 fs/kernfs/file.c:337
#4: ffffffff8ea02160 (system_transition_mutex){+.+.}-{4:4}, at: lock_system_sleep+0x49/0x70 kernel/power/main.c:71
#5: ffffffff8f5e45e0 (device_hotplug_lock){+.+.}-{4:4}, at: hibernate+0x25b/0x680 kernel/power/hibernate.c:805
#6: ffffffff8f3d5240 (acpi_scan_lock){+.+.}-{4:4}, at: acpi_pm_start drivers/acpi/sleep.c:533 [inline]
#6: ffffffff8f3d5240 (acpi_scan_lock){+.+.}-{4:4}, at: acpi_hibernation_begin+0xc8/0x110 drivers/acpi/sleep.c:945
#7: ffffffff8ec848e0 (fs_reclaim){+.+.}-{0:0}, at: __perform_reclaim mm/page_alloc.c:4402 [inline]
#7: ffffffff8ec848e0 (fs_reclaim){+.+.}-{0:0}, at: __alloc_pages_direct_reclaim+0xbd/0x310 mm/page_alloc.c:4427
#8: ffff8880358a40d8 (&type->s_umount_key#83){.+.+}-{4:4}, at: super_trylock_shared fs/super.c:566 [inline]
#8: ffff8880358a40d8 (&type->s_umount_key#83){.+.+}-{4:4}, at: super_cache_scan+0x91/0x4a0 fs/super.c:198

stack backtrace:
CPU: 0 UID: 0 PID: 6195 Comm: syz.3.73 Tainted: G N syzkaller #0 PREEMPT(full)
Tainted: [N]=TEST
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026
Call Trace:
<TASK>
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
shrink_zones mm/vmscan.c:6410 [inline]
do_try_to_free_pages+0x6a3/0x1990 mm/vmscan.c:6472
try_to_free_pages+0x90a/0xe50 mm/vmscan.c:6711
__perform_reclaim mm/page_alloc.c:4405 [inline]
__alloc_pages_direct_reclaim+0x148/0x310 mm/page_alloc.c:4427
__alloc_pages_slowpath+0x59d/0xcc0 mm/page_alloc.c:4876
__alloc_frozen_pages_noprof+0x31f/0x380 mm/page_alloc.c:5317
alloc_pages_mpol+0x212/0x380 mm/mempolicy.c:2490
alloc_frozen_pages_noprof mm/mempolicy.c:2561 [inline]
alloc_pages_noprof+0xac/0x2a0 mm/mempolicy.c:2581
alloc_image_page+0x23/0x130 kernel/power/snapshot.c:231
preallocate_image_pages kernel/power/snapshot.c:1654 [inline]
preallocate_image_memory+0x76/0x140 kernel/power/snapshot.c:1681
hibernate_preallocate_memory+0x43c/0x750 kernel/power/snapshot.c:1960
hibernation_snapshot+0x126/0x3d0 kernel/power/hibernate.c:430
hibernate+0x28f/0x680 kernel/power/hibernate.c:811
state_store+0x234/0x290 kernel/power/main.c:821
kernfs_fop_write_iter+0x3a4/0x540 fs/kernfs/file.c:345
new_sync_write fs/read_write.c:595 [inline]
vfs_write+0x612/0xba0 fs/read_write.c:687
ksys_write+0x150/0x270 fs/read_write.c:739
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
RIP: 0033:0x7fb3bdd9e019
Code: Unable to access opcode bytes at 0x7fb3bdd9dfef.
RSP: 002b:00007fb3beb8f028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007fb3be025fa0 RCX: 00007fb3bdd9e019
RDX: 0000000000000004 RSI: 0000200000000100 RDI: 0000000000000003
RBP: 00007fb3bde3500c R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fb3be026038 R14: 00007fb3be025fa0 R15: 00007ffecece6378
</TASK>
PM: hibernation: Allocated 724545 pages for snapshot
PM: hibernation: Allocated 2898180 kbytes in 41.10 seconds (70.51 MB/s)
printk: Suspending console(s) (use no_console_suspend to debug)


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