[v5.15] INFO: rcu detected stall in sys_mkdirat (3)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: cc5ec8769306 Linux 5.15.196
git tree: linux-5.15.y
console output: https://syzkaller.appspot.com/x/log.txt?x=110b1342580000
kernel config: https://syzkaller.appspot.com/x/.config?x=e1bb6d24ef2164eb
dashboard link: https://syzkaller.appspot.com/bug?extid=750ad6e3a9f8a2f1a88a
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/ed7568bc5bb4/disk-cc5ec876.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/e343e0aaac77/vmlinux-cc5ec876.xz
kernel image: https://storage.googleapis.com/syzbot-assets/089870f2a980/bzImage-cc5ec876.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+750ad6...@syzkaller.appspotmail.com

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 0-....: (7 ticks this GP) idle=531/1/0x4000000000000002 softirq=11526/11526 fqs=5245
(detected by 1, t=10502 jiffies, g=13313, q=1464)
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 5800 Comm: syz.2.524 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
RIP: 0010:check_wait_context kernel/locking/lockdep.c:-1 [inline]
RIP: 0010:__lock_acquire+0x646/0x7c60 kernel/locking/lockdep.c:4962
Code: b4 01 00 00 31 db 48 81 c3 b9 00 00 00 48 89 d8 48 c1 e8 03 42 0f b6 04 00 84 c0 0f 85 2f 61 00 00 45 84 f6 0f 84 25 05 00 00 <0f> b6 1b 48 8b 44 24 58 42 0f b6 04 00 84 c0 0f 85 f3 61 00 00 41
RSP: 0018:ffffc900000070c0 EFLAGS: 00000002
RAX: 0000000000000000 RBX: ffffffff8f946ff9 RCX: ffffffff815c04ed
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff8ffbe0c0
RBP: ffffc90000007310 R08: dffffc0000000000 R09: fffffbfff1ff7c19
R10: fffffbfff1ff7c19 R11: 1ffffffff1ff7c18 R12: ffff8880209ae4f0
R13: ffff8880209ad940 R14: 0000000000000002 R15: ffff8880209ae4d0
FS: 00007f9bc339a6c0(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b3281bff8 CR3: 000000002ab97000 CR4: 00000000003506f0
DR0: 0000200000000300 DR1: 0000200000000300 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
<IRQ>
lock_acquire+0x197/0x3f0 kernel/locking/lockdep.c:5623
rcu_lock_acquire+0x2a/0x30 include/linux/rcupdate.h:313
rcu_read_lock include/linux/rcupdate.h:740 [inline]
__perf_event_output kernel/events/core.c:7800 [inline]
perf_event_output_forward+0x9e/0x280 kernel/events/core.c:7822
__perf_event_overflow+0x364/0x530 kernel/events/core.c:9515
perf_tp_event+0x32c/0xb50 kernel/events/core.c:10047
perf_trace_run_bpf_submit+0xf3/0x1c0 kernel/events/core.c:10021
perf_trace_preemptirq_template+0x2be/0x380 include/trace/events/preemptirq.h:14
trace_irq_enable_rcuidle+0x108/0x180 include/trace/events/preemptirq.h:40
trace_hardirqs_on+0x57/0x80 kernel/trace/trace_preemptirq.c:44
asm_sysvec_irq_work+0x16/0x20 arch/x86/include/asm/idtentry.h:713
RIP: 0010:rcu_read_unlock_special+0x84/0x480 kernel/rcu/tree_plugin.h:674
Code: f1 f1 f1 00 f2 f2 f2 4a 89 04 2b 66 42 c7 44 2b 09 f3 f3 42 c6 44 2b 0b f3 65 44 8b 35 ed 11 9e 7e 41 f7 c6 00 00 f0 00 74 45 <48> c7 44 24 20 0e 36 e0 45 4a c7 04 2b 00 00 00 00 66 42 c7 44 2b
RSP: 0018:ffffc90000007ae0 EFLAGS: 00000206
RAX: 3039d307995f0f00 RBX: 1ffff92000000f60 RCX: 3039d307995f0f00
RDX: dffffc0000000000 RSI: ffffffff8a0b1c60 RDI: ffffffff8a59e580
RBP: ffffc90000007bb8 R08: dffffc0000000000 R09: fffffbfff1ff7c19
R10: fffffbfff1ff7c19 R11: 1ffffffff1ff7c18 R12: ffffffff8c120c00
R13: dffffc0000000000 R14: 0000000000000246 R15: 0000000000000001
__rcu_read_unlock+0x78/0xd0 kernel/rcu/tree_plugin.h:422
rcu_read_unlock include/linux/rcupdate.h:772 [inline]
ieee80211_iterate_active_interfaces_atomic+0x132/0x140 net/mac80211/util.c:831
mac80211_hwsim_beacon+0x9b/0x180 drivers/net/wireless/mac80211_hwsim.c:1865
__run_hrtimer kernel/time/hrtimer.c:1685 [inline]
__hrtimer_run_queues+0x53d/0xc40 kernel/time/hrtimer.c:1749
hrtimer_run_softirq+0x176/0x240 kernel/time/hrtimer.c:1766
handle_softirqs+0x328/0x820 kernel/softirq.c:576
__do_softirq kernel/softirq.c:610 [inline]
invoke_softirq kernel/softirq.c:450 [inline]
__irq_exit_rcu+0x12f/0x220 kernel/softirq.c:659
irq_exit_rcu+0x5/0x20 kernel/softirq.c:671
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline]
sysvec_apic_timer_interrupt+0xa0/0xc0 arch/x86/kernel/apic/apic.c:1108
</IRQ>
<TASK>
asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:deref_stack_reg+0x10/0x120 arch/x86/kernel/unwind_orc.c:356
Code: 0f 8c e6 f4 ff ff 4c 89 f7 e8 dc 9d 87 00 e9 d9 f4 ff ff 0f 1f 80 00 00 00 00 55 41 57 41 56 41 55 41 54 53 48 89 d3 49 89 f6 <49> 89 ff 49 bc 00 00 00 00 00 fc ff df 48 83 c7 08 48 89 f8 48 c1
RSP: 0018:ffffc90002f7f270 EFLAGS: 00000287
RAX: fffffffffffffff0 RBX: ffffc90002f7f3a8 RCX: 0000000000000000
RDX: ffffc90002f7f3a8 RSI: ffffc90002f7f878 RDI: ffffc90002f7f368
RBP: ffffc90002f7f3b0 R08: dffffc0000000000 R09: ffffc90002f7f3b8
R10: fffff520005efe79 R11: 1ffff920005efe77 R12: 1ffffffff1be4876
R13: dffffc0000000000 R14: ffffc90002f7f878 R15: ffffffff8df243b2
unwind_next_frame+0x115d/0x1d90 arch/x86/kernel/unwind_orc.c:-1
arch_stack_walk+0x10c/0x140 arch/x86/kernel/stacktrace.c:25
stack_trace_save+0x98/0xe0 kernel/stacktrace.c:122
kasan_save_stack mm/kasan/common.c:38 [inline]
kasan_set_track mm/kasan/common.c:46 [inline]
set_alloc_info mm/kasan/common.c:434 [inline]
____kasan_kmalloc mm/kasan/common.c:513 [inline]
__kasan_kmalloc+0xb5/0xf0 mm/kasan/common.c:522
kstrdup mm/util.c:60 [inline]
kstrdup_const+0x51/0x90 mm/util.c:83
__kernfs_new_node+0x9b/0x680 fs/kernfs/dir.c:589
kernfs_new_node+0x148/0x250 fs/kernfs/dir.c:669
__kernfs_create_file+0x47/0x2e0 fs/kernfs/file.c:985
cgroup_add_file kernel/cgroup/cgroup.c:4090 [inline]
cgroup_addrm_files+0xa41/0xf00 kernel/cgroup/cgroup.c:4152
css_populate_dir+0x19b/0x2f0 kernel/cgroup/cgroup.c:1739
cgroup_mkdir+0xc47/0xe60 kernel/cgroup/cgroup.c:5604
kernfs_iop_mkdir+0x24c/0x3d0 fs/kernfs/dir.c:1175
vfs_mkdir+0x387/0x570 fs/namei.c:4073
do_mkdirat+0x1d7/0x5a0 fs/namei.c:4098
__do_sys_mkdirat fs/namei.c:4113 [inline]
__se_sys_mkdirat fs/namei.c:4111 [inline]
__x64_sys_mkdirat+0x85/0x90 fs/namei.c:4111
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f9bc51336c9
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:00007f9bc339a038 EFLAGS: 00000246 ORIG_RAX: 0000000000000102
RAX: ffffffffffffffda RBX: 00007f9bc5389fa0 RCX: 00007f9bc51336c9
RDX: 00000000000001ff RSI: 0000200000000000 RDI: ffffffffffffff9c
RBP: 00007f9bc51b5f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f9bc538a038 R14: 00007f9bc5389fa0 R15: 00007fff87cd0bd8
</TASK>


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