[v6.6] INFO: rcu detected stall in sock_alloc_file (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 4791134e4aeb Linux 6.6.118
git tree: linux-6.6.y
console output: https://syzkaller.appspot.com/x/log.txt?x=11c0a01a580000
kernel config: https://syzkaller.appspot.com/x/.config?x=12606d4b8832c7e4
dashboard link: https://syzkaller.appspot.com/bug?extid=0a5a607806b9dcb6d7c9
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/d5853385c5d5/disk-4791134e.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/13d5cf580b4d/vmlinux-4791134e.xz
kernel image: https://storage.googleapis.com/syzbot-assets/a9536fd663f0/bzImage-4791134e.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+0a5a60...@syzkaller.appspotmail.com

rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 0-....: (10478 ticks this GP) idle=c26c/1/0x4000000000000000 softirq=38708/38919 fqs=193
rcu: hardirqs softirqs csw/system
rcu: number: 2142184 698 0
rcu: cputime: 32370 19957 13 ==> 52360(ms)
rcu: (t=10503 jiffies g=47569 q=1648 ncpus=2)
CPU: 0 PID: 12140 Comm: syz.2.1766 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:unwind_next_frame+0xcd6/0x2970 arch/x86/kernel/unwind_orc.c:-1
Code: 84 c0 0f 85 07 1b 00 00 4c 89 f0 48 c1 e8 03 42 0f b6 04 28 84 c0 48 8b 6c 24 10 48 8b 54 24 08 0f 85 08 1b 00 00 48 0f bf 03 <48> 01 c2 e9 1c 01 00 00 e8 9d e0 4a 00 e9 5e 0c 00 00 e8 93 e0 4a
RSP: 0018:ffffc90000006f30 EFLAGS: 00000246
RAX: 0000000000000068 RBX: ffffffff8ecd2830 RCX: ffff88807fc75a00
RDX: ffffc90000007000 RSI: ffffffff8cb9e760 RDI: 0000000000000005
RBP: ffffc900000070b8 R08: ffff88807fc75a00 R09: 0000000000000008
R10: 0000000000000009 R11: 0000000000000100 R12: ffffc90000007068
R13: dffffc0000000000 R14: ffffffff8ecd2831 R15: ffffffff8ecd2834
FS: 00007efef09cb6c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f727dc00218 CR3: 000000005cb99000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000200000000300 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
<IRQ>
__unwind_start+0x66a/0x7e0 arch/x86/kernel/unwind_orc.c:760
unwind_start arch/x86/include/asm/unwind.h:64 [inline]
arch_stack_walk+0xf8/0x190 arch/x86/kernel/stacktrace.c:24
stack_trace_save+0x9c/0xe0 kernel/stacktrace.c:122
kasan_save_stack mm/kasan/common.c:45 [inline]
kasan_set_track+0x4e/0x70 mm/kasan/common.c:52
__kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:328
kasan_slab_alloc include/linux/kasan.h:188 [inline]
slab_post_alloc_hook+0x6e/0x4d0 mm/slab.h:767
slab_alloc_node mm/slub.c:3495 [inline]
slab_alloc mm/slub.c:3503 [inline]
__kmem_cache_alloc_lru mm/slub.c:3510 [inline]
kmem_cache_alloc+0x11e/0x2e0 mm/slub.c:3519
skb_clone+0x1eb/0x370 net/core/skbuff.c:1915
deliver_clone net/bridge/br_forward.c:125 [inline]
maybe_deliver+0x98/0x150 net/bridge/br_forward.c:191
br_flood+0x31b/0x680 net/bridge/br_forward.c:237
br_handle_frame_finish+0x143d/0x1950 net/bridge/br_input.c:215
nf_hook_bridge_pre net/bridge/br_input.c:299 [inline]
br_handle_frame+0xb50/0x14c0 net/bridge/br_input.c:424
__netif_receive_skb_core+0xf6b/0x3ac0 net/core/dev.c:5502
__netif_receive_skb_one_core net/core/dev.c:5606 [inline]
__netif_receive_skb+0x74/0x290 net/core/dev.c:5722
process_backlog+0x380/0x6e0 net/core/dev.c:6050
__napi_poll+0xc0/0x460 net/core/dev.c:6612
napi_poll net/core/dev.c:6679 [inline]
net_rx_action+0x5ea/0xbf0 net/core/dev.c:6815
handle_softirqs+0x280/0x820 kernel/softirq.c:578
__do_softirq kernel/softirq.c:612 [inline]
invoke_softirq kernel/softirq.c:452 [inline]
__irq_exit_rcu+0xc7/0x190 kernel/softirq.c:661
irq_exit_rcu+0x9/0x20 kernel/softirq.c:673
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1088 [inline]
sysvec_apic_timer_interrupt+0xa4/0xc0 arch/x86/kernel/apic/apic.c:1088
</IRQ>
<TASK>
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:687
RIP: 0010:raw_spin_rq_unlock_irq+0x13/0x90 kernel/sched/sched.h:1385
Code: 0f 48 8d 65 d8 5b 41 5c 41 5d 41 5e 41 5f 5d c3 e8 62 5c 11 09 66 90 41 57 41 56 53 66 90 e8 c4 06 1b 09 e8 4f 33 2e 00 fb 5b <41> 5e 41 5f c3 f3 0f 1e fa 49 be 00 00 00 00 00 fc ff df 49 89 ff
RSP: 0018:ffffc9000fe97588 EFLAGS: 00000282
RAX: 52eaced759168700 RBX: ffff8880b8e3cd48 RCX: 52eaced759168700
RDX: dffffc0000000000 RSI: ffffffff8aaabce0 RDI: ffffffff8afc6f80
RBP: ffffc9000fe97790 R08: ffffffff90da952f R09: 1ffffffff21b52a5
R10: dffffc0000000000 R11: fffffbfff21b52a6 R12: dffffc0000000000
R13: ffff8880b8e3c000 R14: ffff88807fc75a00 R15: ffff88807fc75a00
__schedule+0x171e/0x44d0 kernel/sched/core.c:6703
preempt_schedule_common+0x82/0xc0 kernel/sched/core.c:6866
preempt_schedule+0xab/0xc0 kernel/sched/core.c:6890
preempt_schedule_thunk+0x1a/0x30 arch/x86/entry/thunk_64.S:45
__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline]
_raw_spin_unlock_irqrestore+0xfa/0x110 kernel/locking/spinlock.c:194
__debug_check_no_obj_freed lib/debugobjects.c:999 [inline]
debug_check_no_obj_freed+0x51f/0x540 lib/debugobjects.c:1020
free_pages_prepare mm/page_alloc.c:1160 [inline]
free_unref_page_prepare+0x1de/0x8e0 mm/page_alloc.c:2336
free_unref_page+0x32/0x2e0 mm/page_alloc.c:2429
discard_slab mm/slub.c:2127 [inline]
__unfreeze_partials+0x1cf/0x210 mm/slub.c:2667
put_cpu_partial+0x17c/0x250 mm/slub.c:2743
__slab_free+0x31d/0x410 mm/slub.c:3700
qlink_free mm/kasan/quarantine.c:166 [inline]
qlist_free_all+0x75/0xe0 mm/kasan/quarantine.c:185
kasan_quarantine_reduce+0x143/0x160 mm/kasan/quarantine.c:292
__kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:305
kasan_slab_alloc include/linux/kasan.h:188 [inline]
slab_post_alloc_hook+0x6e/0x4d0 mm/slab.h:767
slab_alloc_node mm/slub.c:3495 [inline]
slab_alloc mm/slub.c:3503 [inline]
__kmem_cache_alloc_lru mm/slub.c:3510 [inline]
kmem_cache_alloc_lru+0x115/0x2e0 mm/slub.c:3526
__d_alloc+0x31/0x730 fs/dcache.c:1773
d_alloc_pseudo+0x1d/0x70 fs/dcache.c:1905
alloc_file_pseudo+0xcc/0x200 fs/file_table.c:329
sock_alloc_file+0xb7/0x280 net/socket.c:469
__sys_socketpair+0x2d0/0x550 net/socket.c:1802
__do_sys_socketpair net/socket.c:1831 [inline]
__se_sys_socketpair net/socket.c:1828 [inline]
__x64_sys_socketpair+0x9b/0xb0 net/socket.c:1828
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7efeefb8f749
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007efef09cb038 EFLAGS: 00000246 ORIG_RAX: 0000000000000035
RAX: ffffffffffffffda RBX: 00007efeefde5fa0 RCX: 00007efeefb8f749
RDX: 0000000000000000 RSI: 0000000000000002 RDI: 0000000000000001
RBP: 00007efeefc13f91 R08: 0000000000000000 R09: 0000000000000000
R10: 00002000000001c0 R11: 0000000000000246 R12: 0000000000000000
R13: 00007efeefde6038 R14: 00007efeefde5fa0 R15: 00007ffcc11549b8
</TASK>


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