[syzbot] [nilfs?] possible deadlock in nilfs_evict_inode (3)

From: syzbot
Date: Fri Mar 28 2025 - 10:38:25 EST

Hello,

syzbot found the following issue on:

HEAD commit: 586de92313fc Merge tag 'i2c-for-6.14-rc8' of git://git.ker..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1207243f980000
kernel config: https://syzkaller.appspot.com/x/.config?x=27515cfdbafbb90d
dashboard link: https://syzkaller.appspot.com/bug?extid=cfb767df63e683c533af
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

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

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/7feb34a89c2a/non_bootable_disk-586de923.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/ce0ae238d692/vmlinux-586de923.xz
kernel image: https://storage.googleapis.com/syzbot-assets/c8c843acbfaf/bzImage-586de923.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+cfb767df63e683c533af@xxxxxxxxxxxxxxxxxxxxxxxxx

======================================================
WARNING: possible circular locking dependency detected
6.14.0-rc7-syzkaller-00205-g586de92313fc #0 Not tainted
------------------------------------------------------
kswapd1/82 is trying to acquire lock:
ffff8880440f4610 (sb_internal#2){.+.+}-{0:0}, at: nilfs_evict_inode+0x167/0x500 fs/nilfs2/inode.c:859

but task is already holding lock:
ffffffff8ec3a6c0 (fs_reclaim){+.+.}-{0:0}, at: balance_pgdat mm/vmscan.c:6886 [inline]
ffffffff8ec3a6c0 (fs_reclaim){+.+.}-{0:0}, at: kswapd+0xb9f/0x3b10 mm/vmscan.c:7264

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #4 (fs_reclaim){+.+.}-{0:0}:
lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5851
__fs_reclaim_acquire mm/page_alloc.c:3853 [inline]
fs_reclaim_acquire+0x88/0x130 mm/page_alloc.c:3867
might_alloc include/linux/sched/mm.h:318 [inline]
slab_pre_alloc_hook mm/slub.c:4066 [inline]
slab_alloc_node mm/slub.c:4144 [inline]
kmem_cache_alloc_node_noprof+0x48/0x380 mm/slub.c:4216
__alloc_skb+0x1c3/0x440 net/core/skbuff.c:596
alloc_skb include/linux/skbuff.h:1331 [inline]
alloc_uevent_skb+0x74/0x230 lib/kobject_uevent.c:289
uevent_net_broadcast_untagged lib/kobject_uevent.c:326 [inline]
kobject_uevent_net_broadcast+0x2fd/0x580 lib/kobject_uevent.c:410
kobject_uevent_env+0x57d/0x8e0 lib/kobject_uevent.c:608
kobject_synth_uevent+0x4ef/0xae0 lib/kobject_uevent.c:207
bus_uevent_store+0x116/0x170 drivers/base/bus.c:832
kernfs_fop_write_iter+0x3a0/0x500 fs/kernfs/file.c:334
new_sync_write fs/read_write.c:586 [inline]
vfs_write+0xacf/0xd10 fs/read_write.c:679
ksys_write+0x18f/0x2b0 fs/read_write.c:731
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #3 (uevent_sock_mutex){+.+.}-{4:4}:
lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5851
__mutex_lock_common kernel/locking/mutex.c:585 [inline]
__mutex_lock+0x19c/0x1010 kernel/locking/mutex.c:730
uevent_net_broadcast_untagged lib/kobject_uevent.c:317 [inline]
kobject_uevent_net_broadcast+0x280/0x580 lib/kobject_uevent.c:410
kobject_uevent_env+0x57d/0x8e0 lib/kobject_uevent.c:608
loop_set_size drivers/block/loop.c:235 [inline]
loop_set_status+0x4f8/0x800 drivers/block/loop.c:1292
lo_ioctl+0xce6/0x2870
blkdev_ioctl+0x5d0/0x6f0 block/ioctl.c:693
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:906 [inline]
__se_sys_ioctl+0xf5/0x170 fs/ioctl.c:892
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #2 (&q->q_usage_counter(io)#17){++++}-{0:0}:
lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5851
bio_queue_enter block/blk.h:78 [inline]
blk_mq_submit_bio+0x14e1/0x25d0 block/blk-mq.c:3091
__submit_bio+0x2cf/0x6a0 block/blk-core.c:628
__submit_bio_noacct_mq block/blk-core.c:715 [inline]
submit_bio_noacct_nocheck+0x4d3/0xe30 block/blk-core.c:744
nilfs_mdt_submit_block+0x5c5/0x880 fs/nilfs2/mdt.c:153
nilfs_mdt_read_block+0xeb/0x430 fs/nilfs2/mdt.c:178
nilfs_mdt_get_block+0x10a/0xa30 fs/nilfs2/mdt.c:254
nilfs_palloc_get_block+0x181/0x2a0 fs/nilfs2/alloc.c:239
nilfs_palloc_get_bitmap_block fs/nilfs2/alloc.c:317 [inline]
nilfs_palloc_prepare_alloc_entry+0x71c/0x1070 fs/nilfs2/alloc.c:621
nilfs_ifile_create_inode+0x156/0x3a0 fs/nilfs2/ifile.c:61
nilfs_new_inode+0x254/0x830 fs/nilfs2/inode.c:321
nilfs_create+0xfd/0x2d0 fs/nilfs2/namei.c:98
lookup_open fs/namei.c:3651 [inline]
open_last_lookups fs/namei.c:3750 [inline]
path_openat+0x193c/0x3590 fs/namei.c:3986
do_filp_open+0x27f/0x4e0 fs/namei.c:4016
do_sys_openat2+0x13e/0x1d0 fs/open.c:1428
do_sys_open fs/open.c:1443 [inline]
__do_sys_openat fs/open.c:1459 [inline]
__se_sys_openat fs/open.c:1454 [inline]
__x64_sys_openat+0x247/0x2a0 fs/open.c:1454
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #1 (&nilfs->ns_segctor_sem){++++}-{4:4}:
lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5851
down_read+0xb1/0xa40 kernel/locking/rwsem.c:1524
nilfs_transaction_begin+0x320/0x6e0 fs/nilfs2/segment.c:221
nilfs_create+0xc7/0x2d0 fs/nilfs2/namei.c:95
lookup_open fs/namei.c:3651 [inline]
open_last_lookups fs/namei.c:3750 [inline]
path_openat+0x193c/0x3590 fs/namei.c:3986
do_filp_open+0x27f/0x4e0 fs/namei.c:4016
do_sys_openat2+0x13e/0x1d0 fs/open.c:1428
do_sys_open fs/open.c:1443 [inline]
__do_sys_openat fs/open.c:1459 [inline]
__se_sys_openat fs/open.c:1454 [inline]
__x64_sys_openat+0x247/0x2a0 fs/open.c:1454
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #0 (sb_internal#2){.+.+}-{0:0}:
check_prev_add kernel/locking/lockdep.c:3163 [inline]
check_prevs_add kernel/locking/lockdep.c:3282 [inline]
validate_chain+0x18ef/0x5920 kernel/locking/lockdep.c:3906
__lock_acquire+0x1397/0x2100 kernel/locking/lockdep.c:5228
lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5851
percpu_down_read include/linux/percpu-rwsem.h:51 [inline]
__sb_start_write include/linux/fs.h:1785 [inline]
sb_start_intwrite include/linux/fs.h:1968 [inline]
nilfs_transaction_begin+0x216/0x6e0 fs/nilfs2/segment.c:218
nilfs_evict_inode+0x167/0x500 fs/nilfs2/inode.c:859
evict+0x4e8/0x9a0 fs/inode.c:796
__dentry_kill+0x20d/0x630 fs/dcache.c:643
shrink_kill+0xa9/0x2c0 fs/dcache.c:1088
shrink_dentry_list+0x2c0/0x5b0 fs/dcache.c:1115
prune_dcache_sb+0x10f/0x180 fs/dcache.c:1196
super_cache_scan+0x34f/0x4b0 fs/super.c:221
do_shrink_slab+0x72d/0x1160 mm/shrinker.c:437
shrink_slab_memcg mm/shrinker.c:550 [inline]
shrink_slab+0x878/0x14d0 mm/shrinker.c:628
shrink_one+0x43b/0x850 mm/vmscan.c:4868
shrink_many mm/vmscan.c:4929 [inline]
lru_gen_shrink_node mm/vmscan.c:5007 [inline]
shrink_node+0x379b/0x3e20 mm/vmscan.c:5978
kswapd_shrink_node mm/vmscan.c:6807 [inline]
balance_pgdat mm/vmscan.c:6999 [inline]
kswapd+0x20f3/0x3b10 mm/vmscan.c:7264
kthread+0x7a9/0x920 kernel/kthread.c:464
ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:148
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

other info that might help us debug this:

Chain exists of:
sb_internal#2 --> uevent_sock_mutex --> fs_reclaim

Possible unsafe locking scenario:

CPU0 CPU1
---- ----
lock(fs_reclaim);
lock(uevent_sock_mutex);
lock(fs_reclaim);
rlock(sb_internal#2);

*** DEADLOCK ***

2 locks held by kswapd1/82:
#0: ffffffff8ec3a6c0 (fs_reclaim){+.+.}-{0:0}, at: balance_pgdat mm/vmscan.c:6886 [inline]
#0: ffffffff8ec3a6c0 (fs_reclaim){+.+.}-{0:0}, at: kswapd+0xb9f/0x3b10 mm/vmscan.c:7264
#1: ffff8880440f40e0 (&type->s_umount_key#50){.+.+}-{4:4}, at: super_trylock_shared fs/super.c:562 [inline]
#1: ffff8880440f40e0 (&type->s_umount_key#50){.+.+}-{4:4}, at: super_cache_scan+0x94/0x4b0 fs/super.c:196

stack backtrace:
CPU: 0 UID: 0 PID: 82 Comm: kswapd1 Not tainted 6.14.0-rc7-syzkaller-00205-g586de92313fc #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:94 [inline]
dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
print_circular_bug+0x13a/0x1b0 kernel/locking/lockdep.c:2076
check_noncircular+0x36a/0x4a0 kernel/locking/lockdep.c:2208
check_prev_add kernel/locking/lockdep.c:3163 [inline]
check_prevs_add kernel/locking/lockdep.c:3282 [inline]
validate_chain+0x18ef/0x5920 kernel/locking/lockdep.c:3906
__lock_acquire+0x1397/0x2100 kernel/locking/lockdep.c:5228
lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5851
percpu_down_read include/linux/percpu-rwsem.h:51 [inline]
__sb_start_write include/linux/fs.h:1785 [inline]
sb_start_intwrite include/linux/fs.h:1968 [inline]
nilfs_transaction_begin+0x216/0x6e0 fs/nilfs2/segment.c:218
nilfs_evict_inode+0x167/0x500 fs/nilfs2/inode.c:859
evict+0x4e8/0x9a0 fs/inode.c:796
__dentry_kill+0x20d/0x630 fs/dcache.c:643
shrink_kill+0xa9/0x2c0 fs/dcache.c:1088
shrink_dentry_list+0x2c0/0x5b0 fs/dcache.c:1115
prune_dcache_sb+0x10f/0x180 fs/dcache.c:1196
super_cache_scan+0x34f/0x4b0 fs/super.c:221
do_shrink_slab+0x72d/0x1160 mm/shrinker.c:437
shrink_slab_memcg mm/shrinker.c:550 [inline]
shrink_slab+0x878/0x14d0 mm/shrinker.c:628
shrink_one+0x43b/0x850 mm/vmscan.c:4868
shrink_many mm/vmscan.c:4929 [inline]
lru_gen_shrink_node mm/vmscan.c:5007 [inline]
shrink_node+0x379b/0x3e20 mm/vmscan.c:5978
kswapd_shrink_node mm/vmscan.c:6807 [inline]
balance_pgdat mm/vmscan.c:6999 [inline]
kswapd+0x20f3/0x3b10 mm/vmscan.c:7264
kthread+0x7a9/0x920 kernel/kthread.c:464
ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:148
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
</TASK>


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