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List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Received: by 2002:a05:6e02:2141:b0:3e5:7f54:dcda with SMTP id e9e14a558f8ab-3e6765c3e5cmr43319725ab.1.1755606933212; Tue, 19 Aug 2025 05:35:33 -0700 (PDT) Date: Tue, 19 Aug 2025 05:35:33 -0700 In-Reply-To: <673fdc18.050a0220.363a1b.012c.GAE@google.com> X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <68a46f95.050a0220.e29e5.00c3.GAE@google.com> Subject: Re: [syzbot] [mm?] INFO: rcu detected stall in security_file_ioctl (9) From: syzbot To: akpm@linux-foundation.org, andrii@kernel.org, ast@kernel.org, bpf@vger.kernel.org, brauner@kernel.org, daniel@iogearbox.net, jack@suse.cz, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, netdev@vger.kernel.org, syzkaller-bugs@googlegroups.com, viro@zeniv.linux.org.uk Content-Type: text/plain; charset="UTF-8" syzbot has found a reproducer for the following issue on: HEAD commit: 864e3396976e net: gso: Forbid IPv6 TSO with extensions on .. git tree: net console output: https://syzkaller.appspot.com/x/log.txt?x=144e26f0580000 kernel config: https://syzkaller.appspot.com/x/.config?x=c321f33e4545e2a1 dashboard link: https://syzkaller.appspot.com/bug?extid=b6f8640465bdf47ca708 compiler: Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=170a43bc580000 Downloadable assets: disk image: https://storage.googleapis.com/syzbot-assets/576f260f8fdb/disk-864e3396.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/90ce2b40a623/vmlinux-864e3396.xz kernel image: https://storage.googleapis.com/syzbot-assets/e9f2532beed2/bzImage-864e3396.xz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+b6f8640465bdf47ca708@syzkaller.appspotmail.com rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: 1-...!: (3 ticks this GP) idle=3c4c/1/0x4000000000000000 softirq=18260/18260 fqs=0 rcu: (detected by 0, t=10502 jiffies, g=12221, q=404 ncpus=2) Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 UID: 0 PID: 6109 Comm: syz.0.22 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025 RIP: 0010:memory_is_poisoned_n mm/kasan/generic.c:137 [inline] RIP: 0010:memory_is_poisoned mm/kasan/generic.c:161 [inline] RIP: 0010:check_region_inline mm/kasan/generic.c:180 [inline] RIP: 0010:kasan_check_range+0x29f/0x2c0 mm/kasan/generic.c:189 Code: f3 49 83 c3 05 eb 07 4d 01 f3 49 83 c3 06 4d 89 dc 4d 85 db 0f 84 44 ff ff ff 4d 01 d1 4d 39 cc 75 11 41 83 e0 07 45 0f be 09 <45> 39 c8 0f 8c 2b ff ff ff 0f b6 d2 e8 a0 ef ff ff 34 01 e9 1c ff RSP: 0018:ffffc90000a08ae8 EFLAGS: 00000006 RAX: 00000000ffffff01 RBX: ffffffffffffffff RCX: ffffffff819e00e1 RDX: 0000000000000001 RSI: 0000000000000004 RDI: ffffc90000a08b60 RBP: ffffc90000a08bd0 R08: 0000000000000003 R09: 0000000000000004 R10: dffffc0000000000 R11: fffff5200014116c R12: fffff5200014116c R13: ffffffff99d527c0 R14: fffff5200014116d R15: 1ffff9200014116c FS: 00007f17a98396c0(0000) GS:ffff888125d1b000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000200000000600 CR3: 000000006fc8c000 CR4: 00000000003526f0 Call Trace: instrument_atomic_read_write include/linux/instrumented.h:96 [inline] atomic_try_cmpxchg_acquire include/linux/atomic/atomic-instrumented.h:1301 [inline] queued_spin_lock include/asm-generic/qspinlock.h:111 [inline] do_raw_spin_lock+0x121/0x290 kernel/locking/spinlock_debug.c:116 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:111 [inline] _raw_spin_lock_irqsave+0xb3/0xf0 kernel/locking/spinlock.c:162 debug_object_activate+0xbb/0x420 lib/debugobjects.c:818 debug_hrtimer_activate kernel/time/hrtimer.c:445 [inline] debug_activate kernel/time/hrtimer.c:484 [inline] enqueue_hrtimer+0x30/0x3a0 kernel/time/hrtimer.c:1088 __run_hrtimer kernel/time/hrtimer.c:1778 [inline] __hrtimer_run_queues+0x656/0xc60 kernel/time/hrtimer.c:1825 hrtimer_interrupt+0x45b/0xaa0 kernel/time/hrtimer.c:1887 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1039 [inline] __sysvec_apic_timer_interrupt+0x108/0x410 arch/x86/kernel/apic/apic.c:1056 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1050 [inline] sysvec_apic_timer_interrupt+0xa1/0xc0 arch/x86/kernel/apic/apic.c:1050 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702 RIP: 0010:bytes_is_nonzero mm/kasan/generic.c:86 [inline] RIP: 0010:memory_is_nonzero mm/kasan/generic.c:104 [inline] RIP: 0010:memory_is_poisoned_n mm/kasan/generic.c:129 [inline] RIP: 0010:memory_is_poisoned mm/kasan/generic.c:161 [inline] RIP: 0010:check_region_inline mm/kasan/generic.c:180 [inline] RIP: 0010:kasan_check_range+0x89/0x2c0 mm/kasan/generic.c:189 Code: ff df 4f 8d 1c 17 49 ff c8 4d 89 c1 49 c1 e9 03 48 bb 01 00 00 00 00 fc ff df 4d 8d 34 19 4d 89 f4 4d 29 dc 49 83 fc 10 7f 29 <4d> 85 e4 0f 84 41 01 00 00 4c 89 cb 48 f7 d3 4c 01 fb 41 80 3b 00 RSP: 0018:ffffc90003037910 EFLAGS: 00000283 RAX: ffffffff8b758901 RBX: dffffc0000000001 RCX: ffffffff8b7589f6 RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff8c935a00 RBP: ffffffff8c935a08 R08: ffffffff8c935a07 R09: 1ffffffff1926b40 R10: dffffc0000000000 R11: fffffbfff1926b40 R12: 0000000000000001 R13: ffffc90003037aa0 R14: fffffbfff1926b41 R15: 1ffffffff1926b40 __asan_memcpy+0x29/0x70 mm/kasan/shadow.c:105 vsnprintf+0x386/0xf00 lib/vsprintf.c:2878 dynamic_dname+0xfc/0x1b0 fs/d_path.c:308 tomoyo_realpath_from_path+0x170/0x5d0 security/tomoyo/realpath.c:258 tomoyo_get_realpath security/tomoyo/file.c:151 [inline] tomoyo_path_number_perm+0x1e8/0x5a0 security/tomoyo/file.c:723 security_file_ioctl+0xcb/0x2d0 security/security.c:2943 __do_sys_ioctl fs/ioctl.c:592 [inline] __se_sys_ioctl+0x47/0x170 fs/ioctl.c:584 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f17a898ebe9 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:00007f17a9839038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f17a8bb5fa0 RCX: 00007f17a898ebe9 RDX: 0000200000000600 RSI: 0000000000008933 RDI: 0000000000000003 RBP: 00007f17a8a11e19 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f17a8bb6038 R14: 00007f17a8bb5fa0 R15: 00007ffccbbdc5c8 rcu: rcu_preempt kthread timer wakeup didn't happen for 10501 jiffies! g12221 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 rcu: Possible timer handling issue on cpu=1 timer-softirq=3961 rcu: rcu_preempt kthread starved for 10502 jiffies! g12221 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->cpu=1 rcu: Unless rcu_preempt kthread gets sufficient CPU time, OOM is now expected behavior. rcu: RCU grace-period kthread stack dump: task:rcu_preempt state:I stack:27224 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00004000 Call Trace: context_switch kernel/sched/core.c:5357 [inline] __schedule+0x1798/0x4cc0 kernel/sched/core.c:6961 __schedule_loop kernel/sched/core.c:7043 [inline] schedule+0x165/0x360 kernel/sched/core.c:7058 schedule_timeout+0x12b/0x270 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x301/0x1540 kernel/rcu/tree.c:2083 rcu_gp_kthread+0x99/0x390 kernel/rcu/tree.c:2285 kthread+0x711/0x8a0 kernel/kthread.c:463 ret_from_fork+0x3f9/0x770 arch/x86/kernel/process.c:148 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 --- If you want syzbot to run the reproducer, reply with: #syz test: git://repo/address.git branch-or-commit-hash If you attach or paste a git patch, syzbot will apply it before testing.