[syzbot] [crypto?] possible deadlock in padata_do_serial

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 2ae2aaafb214 Add linux-next specific files for 20250624
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=10deb70c580000
kernel config: https://syzkaller.appspot.com/x/.config?x=d85d3c440a754f86
dashboard link: https://syzkaller.appspot.com/bug?extid=bd936ccd4339cea66e6b
compiler: Debian clang version 20.1.6 (++20250514063057+1e4d39e07757-1~exp1~20250514183223.118), Debian LLD 20.1.6

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/689f558e5251/disk-2ae2aaaf.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/355aae0f4972/vmlinux-2ae2aaaf.xz
kernel image: https://storage.googleapis.com/syzbot-assets/94e736ebe604/bzImage-2ae2aaaf.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+bd936c...@syzkaller.appspotmail.com

============================================
WARNING: possible recursive locking detected
6.16.0-rc3-next-20250624-syzkaller #0 Not tainted
--------------------------------------------
kworker/u8:11/20346 is trying to acquire lock:
ffffe8ffffd55fd8 (&pd_list->lock){+...}-{3:3}, at: spin_lock include/linux/spinlock.h:351 [inline]
ffffe8ffffd55fd8 (&pd_list->lock){+...}-{3:3}, at: padata_find_next kernel/padata.c:256 [inline]
ffffe8ffffd55fd8 (&pd_list->lock){+...}-{3:3}, at: padata_reorder kernel/padata.c:309 [inline]
ffffe8ffffd55fd8 (&pd_list->lock){+...}-{3:3}, at: padata_do_serial+0x73e/0xb80 kernel/padata.c:379

but task is already holding lock:
ffffe8ffffd5f4d8 (&pd_list->lock){+...}-{3:3}, at: spin_lock include/linux/spinlock.h:351 [inline]
ffffe8ffffd5f4d8 (&pd_list->lock){+...}-{3:3}, at: padata_reorder kernel/padata.c:300 [inline]
ffffe8ffffd5f4d8 (&pd_list->lock){+...}-{3:3}, at: padata_do_serial+0x5b5/0xb80 kernel/padata.c:379

other info that might help us debug this:
Possible unsafe locking scenario:

CPU0
----
lock(&pd_list->lock);
lock(&pd_list->lock);

*** DEADLOCK ***

May be due to missing lock nesting notation

3 locks held by kworker/u8:11/20346:
#0: ffff888146e84948 ((wq_completion)pencrypt_parallel){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3214 [inline]
#0: ffff888146e84948 ((wq_completion)pencrypt_parallel){+.+.}-{0:0}, at: process_scheduled_works+0x9b4/0x17b0 kernel/workqueue.c:3322
#1: ffffc9000bf7fbc0 ((work_completion)(&pw->pw_work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3215 [inline]
#1: ffffc9000bf7fbc0 ((work_completion)(&pw->pw_work)){+.+.}-{0:0}, at: process_scheduled_works+0x9ef/0x17b0 kernel/workqueue.c:3322
#2: ffffe8ffffd5f4d8 (&pd_list->lock){+...}-{3:3}, at: spin_lock include/linux/spinlock.h:351 [inline]
#2: ffffe8ffffd5f4d8 (&pd_list->lock){+...}-{3:3}, at: padata_reorder kernel/padata.c:300 [inline]
#2: ffffe8ffffd5f4d8 (&pd_list->lock){+...}-{3:3}, at: padata_do_serial+0x5b5/0xb80 kernel/padata.c:379

stack backtrace:
CPU: 1 UID: 0 PID: 20346 Comm: kworker/u8:11 Not tainted 6.16.0-rc3-next-20250624-syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Workqueue: pencrypt_parallel padata_parallel_worker
Call Trace:
<TASK>
dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
print_deadlock_bug+0x28b/0x2a0 kernel/locking/lockdep.c:3044
check_deadlock kernel/locking/lockdep.c:3096 [inline]
validate_chain+0x1a3f/0x2140 kernel/locking/lockdep.c:3898
__lock_acquire+0xab9/0xd20 kernel/locking/lockdep.c:5240
lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5871
__raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
_raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154
spin_lock include/linux/spinlock.h:351 [inline]
padata_find_next kernel/padata.c:256 [inline]
padata_reorder kernel/padata.c:309 [inline]
padata_do_serial+0x73e/0xb80 kernel/padata.c:379
padata_parallel_worker+0x75/0x1d0 kernel/padata.c:157
process_one_work kernel/workqueue.c:3239 [inline]
process_scheduled_works+0xade/0x17b0 kernel/workqueue.c:3322
worker_thread+0x8a0/0xda0 kernel/workqueue.c:3403
kthread+0x711/0x8a0 kernel/kthread.c:463
ret_from_fork+0x3fc/0x770 arch/x86/kernel/process.c:148
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
</TASK>


---
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[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit: 02ffd6f89c50 Merge tag 'bpf-fixes' of git://git.kernel.org..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=124f6934580000
kernel config: https://syzkaller.appspot.com/x/.config?x=c1f4909b95fa1ed
dashboard link: https://syzkaller.appspot.com/bug?extid=bd936ccd4339cea66e6b
compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=12e46b12580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1598a47c580000

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-02ffd6f8.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/56f3c676fa83/vmlinux-02ffd6f8.xz
kernel image: https://storage.googleapis.com/syzbot-assets/b17e95e57bfa/bzImage-02ffd6f8.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+bd936c...@syzkaller.appspotmail.com

============================================
WARNING: possible recursive locking detected

syzkaller #0 Not tainted
--------------------------------------------
kworker/u32:5/96 is trying to acquire lock:
ffffe8fefc53dbc8 (&pd_list->lock){+...}-{3:3}, at: spin_lock include/linux/spinlock.h:351 [inline]
ffffe8fefc53dbc8 (&pd_list->lock){+...}-{3:3}, at: padata_find_next kernel/padata.c:256 [inline]
ffffe8fefc53dbc8 (&pd_list->lock){+...}-{3:3}, at: padata_reorder kernel/padata.c:309 [inline]
ffffe8fefc53dbc8 (&pd_list->lock){+...}-{3:3}, at: padata_do_serial+0x7bd/0xd20 kernel/padata.c:379

but task is already holding lock:

ffffe8fefc53dc18 (&pd_list->lock){+...}-{3:3}, at: spin_lock include/linux/spinlock.h:351 [inline]
ffffe8fefc53dc18 (&pd_list->lock){+...}-{3:3}, at: padata_reorder kernel/padata.c:300 [inline]
ffffe8fefc53dc18 (&pd_list->lock){+...}-{3:3}, at: padata_do_serial+0x697/0xd20 kernel/padata.c:379

other info that might help us debug this:
Possible unsafe locking scenario:

CPU0
----
lock(&pd_list->lock);
lock(&pd_list->lock);

*** DEADLOCK ***

May be due to missing lock nesting notation

3 locks held by kworker/u32:5/96:
#0: ffff888022495148 ((wq_completion)pdecrypt_parallel){+.+.}-{0:0}, at: process_one_work+0x12a2/0x1b70 kernel/workqueue.c:3211
#1: ffffc9000167fd10 ((work_completion)(&pw->pw_work)){+.+.}-{0:0}, at: process_one_work+0x929/0x1b70 kernel/workqueue.c:3212
#2: ffffe8fefc53dc18 (&pd_list->lock){+...}-{3:3}, at: spin_lock include/linux/spinlock.h:351 [inline]
#2: ffffe8fefc53dc18 (&pd_list->lock){+...}-{3:3}, at: padata_reorder kernel/padata.c:300 [inline]
#2: ffffe8fefc53dc18 (&pd_list->lock){+...}-{3:3}, at: padata_do_serial+0x697/0xd20 kernel/padata.c:379

stack backtrace:
CPU: 2 UID: 0 PID: 96 Comm: kworker/u32:5 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
Workqueue: pdecrypt_parallel padata_parallel_worker
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:94 [inline]
dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
print_deadlock_bug+0x1e9/0x240 kernel/locking/lockdep.c:3041
check_deadlock kernel/locking/lockdep.c:3093 [inline]
validate_chain kernel/locking/lockdep.c:3895 [inline]
__lock_acquire+0x1133/0x1ce0 kernel/locking/lockdep.c:5237
lock_acquire kernel/locking/lockdep.c:5868 [inline]
lock_acquire+0x179/0x350 kernel/locking/lockdep.c:5825

__raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
_raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154
spin_lock include/linux/spinlock.h:351 [inline]
padata_find_next kernel/padata.c:256 [inline]
padata_reorder kernel/padata.c:309 [inline]

padata_do_serial+0x7bd/0xd20 kernel/padata.c:379
pcrypt_aead_dec+0x5b/0x70 crypto/pcrypt.c:140
padata_parallel_worker+0x62/0xb0 kernel/padata.c:157
process_one_work+0x9cc/0x1b70 kernel/workqueue.c:3236
process_scheduled_works kernel/workqueue.c:3319 [inline]
worker_thread+0x6c8/0xf10 kernel/workqueue.c:3400
kthread+0x3c2/0x780 kernel/kthread.c:463
ret_from_fork+0x56a/0x730 arch/x86/kernel/process.c:148

ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
</TASK>


---

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