[v6.6] INFO: rcu detected stall in sock_write_iter

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: cc1a1c5b404a Linux 6.6.103
git tree: linux-6.6.y
console output: https://syzkaller.appspot.com/x/log.txt?x=16e3ee62580000
kernel config: https://syzkaller.appspot.com/x/.config?x=412020841cf033b0
dashboard link: https://syzkaller.appspot.com/bug?extid=c2a6e327aaf073c12cf2
compiler: Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/182772cad8cb/disk-cc1a1c5b.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/9cf18a984bd5/vmlinux-cc1a1c5b.xz
kernel image: https://storage.googleapis.com/syzbot-assets/fd4621d0598e/bzImage-cc1a1c5b.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+c2a6e3...@syzkaller.appspotmail.com

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 1-....: (0 ticks this GP) idle=0d24/1/0x4000000000000000 softirq=14887/14887 fqs=2049
rcu: hardirqs softirqs csw/system
rcu: number: 9067779 0 0
rcu: cputime: 23962 0 0 ==> 52550(ms)
rcu: (detected by 0, t=10506 jiffies, g=14481, q=545 ncpus=2)
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 6735 Comm: syz.3.307 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
RIP: 0010:native_apic_msr_eoi+0xf/0x10 arch/x86/include/asm/apic.h:202
Code: c3 89 c6 89 da 48 c7 c7 a0 89 b9 8c 89 c5 e8 28 1f 18 03 89 e8 eb e3 0f 1f 40 00 f3 0f 1e fa b9 0b 08 00 00 31 c0 31 d2 0f 30 <c3> f3 0f 1e fa 81 ff cf 00 00 00 7f 0c 83 ff 20 74 2a 83 ff 30 74
RSP: 0018:ffffc900001f0fd8 EFLAGS: 00000046
RAX: 0000000000000000 RBX: ffffc9000c8871a8 RCX: 000000000000080b
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffc9000c8871a8
RBP: 0000000000000000 R08: ffffffff8e4a8f2f R09: 1ffffffff1c951e5
R10: dffffc0000000000 R11: ffffc900001f0ff8 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
FS: 00007f4a324bd6c0(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00002000003c0000 CR3: 000000002dd62000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
<IRQ>
apic_eoi arch/x86/include/asm/apic.h:409 [inline]
__sysvec_irq_work+0x11/0x380 arch/x86/kernel/irq_work.c:19
instr_sysvec_irq_work arch/x86/kernel/irq_work.c:17 [inline]
sysvec_irq_work+0x9c/0xc0 arch/x86/kernel/irq_work.c:17
</IRQ>
<TASK>
asm_sysvec_irq_work+0x1a/0x20 arch/x86/include/asm/idtentry.h:723
RIP: 0010:finish_task_switch+0x26a/0x920 kernel/sched/core.c:5254
Code: 0f 84 37 01 00 00 48 85 db 0f 85 56 01 00 00 0f 1f 44 00 00 4c 8b 75 d0 4c 89 e7 e8 20 54 1b 09 e8 ab a6 2f 00 fb 4c 8b 65 c0 <49> 8d bc 24 f8 15 00 00 48 89 f8 48 c1 e8 03 42 0f b6 04 28 84 c0
RSP: 0018:ffffc9000c887258 EFLAGS: 00000282
RAX: ae8cc09d55d2cc00 RBX: 0000000000000000 RCX: ae8cc09d55d2cc00
RDX: dffffc0000000000 RSI: ffffffff8aaaba20 RDI: ffffffff8afc7040
RBP: ffffc9000c8872b0 R08: ffffffff90da560f R09: 1ffffffff21b4ac1
R10: dffffc0000000000 R11: fffffbfff21b4ac2 R12: ffff88802830bc00
R13: dffffc0000000000 R14: ffff88802580bc00 R15: ffff8880b8f3cf08
context_switch kernel/sched/core.c:5383 [inline]
__schedule+0x14da/0x44d0 kernel/sched/core.c:6699
preempt_schedule_irq+0xb5/0x140 kernel/sched/core.c:7009
irqentry_exit+0x67/0x70 kernel/entry/common.c:438
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:687
RIP: 0010:clear_page_erms+0xb/0x10 arch/x86/lib/clear_page_64.S:50
Code: 48 89 47 20 48 89 47 28 48 89 47 30 48 89 47 38 48 8d 7f 40 75 d9 90 c3 90 90 90 90 90 90 90 f3 0f 1e fa b9 00 10 00 00 31 c0 <f3> aa c3 90 90 f3 0f 1e fa 48 83 f9 40 73 36 83 f9 08 73 0f 85 c9
RSP: 0018:ffffc9000c887630 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000003 RCX: 0000000000000500
RDX: ffff88807c16b000 RSI: 0000000000000005 RDI: ffff88807c16bb00
RBP: ffffea0001f05a00 R08: ffffea0001f05a37 R09: 0000000000000000
R10: ffffed100f82d000 R11: fffff940003e0b47 R12: 0000000000000000
R13: 0000000000000001 R14: ffffea0001f05a00 R15: 0000000000000008
clear_page arch/x86/include/asm/page_64.h:54 [inline]
clear_highpage_kasan_tagged include/linux/highmem.h:248 [inline]
kernel_init_pages mm/page_alloc.c:1074 [inline]
post_alloc_hook+0xf7/0x210 mm/page_alloc.c:1552
prep_new_page mm/page_alloc.c:1561 [inline]
get_page_from_freelist+0x195c/0x19f0 mm/page_alloc.c:3191
__alloc_pages+0x1e3/0x460 mm/page_alloc.c:4457
skb_page_frag_refill+0x179/0x310 net/core/sock.c:2942
sk_page_frag_refill+0x4c/0xe0 net/core/sock.c:2962
kcm_sendmsg+0x681/0x2880 net/kcm/kcmsock.c:808
sock_sendmsg_nosec net/socket.c:730 [inline]
__sock_sendmsg net/socket.c:745 [inline]
sock_write_iter+0x2bb/0x3f0 net/socket.c:1160
call_write_iter include/linux/fs.h:2018 [inline]
new_sync_write fs/read_write.c:491 [inline]
vfs_write+0x43b/0x940 fs/read_write.c:584
ksys_write+0x147/0x250 fs/read_write.c:637
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: 0033:0x7f4a3158ebe9
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:00007f4a324bd038 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f4a317c5fa0 RCX: 00007f4a3158ebe9
RDX: 00000000fffffdef RSI: 0000200000000140 RDI: 0000000000000005
RBP: 00007f4a31611e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f4a317c6038 R14: 00007f4a317c5fa0 R15: 00007ffebc96dc28
</TASK>


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