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Message-ID: <688fa86e.050a0220.1fc43d.0005.GAE@google.com>
Date: Sun, 03 Aug 2025 11:20:30 -0700
From: syzbot <syzbot+6ed94e81a1492fe1d512@...kaller.appspotmail.com>
To: anna-maria@...utronix.de, frederic@...nel.org,
linux-kernel@...r.kernel.org, syzkaller-bugs@...glegroups.com,
tglx@...utronix.de
Subject: [syzbot] [kernel?] INFO: task hung in vfs_coredump (2)
Hello,
syzbot found the following issue on:
HEAD commit: d086c886ceb9 Add linux-next specific files for 20250718
git tree: linux-next
console+strace: https://syzkaller.appspot.com/x/log.txt?x=127b0ca2580000
kernel config: https://syzkaller.appspot.com/x/.config?x=69896dd7b8c4e81e
dashboard link: https://syzkaller.appspot.com/bug?extid=6ed94e81a1492fe1d512
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=12dbcca2580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=13238834580000
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/54504fbc2437/disk-d086c886.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/b427b00abffe/vmlinux-d086c886.xz
kernel image: https://storage.googleapis.com/syzbot-assets/5a87731b006b/bzImage-d086c886.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+6ed94e81a1492fe1d512@...kaller.appspotmail.com
INFO: task syz-executor104:5856 blocked for more than 143 seconds.
Not tainted 6.16.0-rc6-next-20250718-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor104 state:D stack:26808 pid:5856 tgid:5854 ppid:5853 task_flags:0x400640 flags:0x00004006
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5351 [inline]
__schedule+0x1737/0x4d30 kernel/sched/core.c:6954
__schedule_loop kernel/sched/core.c:7036 [inline]
schedule+0x165/0x360 kernel/sched/core.c:7051
schedule_timeout+0x9a/0x270 kernel/time/sleep_timeout.c:75
do_wait_for_common kernel/sched/completion.c:100 [inline]
__wait_for_common+0x3da/0x710 kernel/sched/completion.c:121
wait_for_common kernel/sched/completion.c:132 [inline]
wait_for_completion_state+0x1c/0x40 kernel/sched/completion.c:269
coredump_wait fs/coredump.c:534 [inline]
vfs_coredump+0x8c2/0x2ab0 fs/coredump.c:1128
get_signal+0x1109/0x1340 kernel/signal.c:3019
arch_do_signal_or_restart+0x9a/0x750 arch/x86/kernel/signal.c:337
exit_to_user_mode_loop+0x75/0x110 kernel/entry/common.c:40
exit_to_user_mode_prepare include/linux/irq-entry-common.h:208 [inline]
syscall_exit_to_user_mode_work include/linux/entry-common.h:175 [inline]
syscall_exit_to_user_mode include/linux/entry-common.h:210 [inline]
do_syscall_64+0x2bd/0x3b0 arch/x86/entry/syscall_64.c:100
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f7bc88c77a9
RSP: 002b:00007f7bc885f198 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: 00000000000000ca RBX: 00007f7bc89513f8 RCX: 00007f7bc88c77a9
RDX: 00000000000f4240 RSI: 0000000000000081 RDI: 00007f7bc89513fc
RBP: 00007f7bc89513f0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f7bc891e0c4
R13: 000000000000006e R14: 00002000000003c0 R15: 00002000000001c0
</TASK>
Showing all locks held in the system:
1 lock held by khungtaskd/31:
#0: ffffffff8e53d8a0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
#0: ffffffff8e53d8a0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline]
#0: ffffffff8e53d8a0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6770
2 locks held by getty/5611:
#0: ffff88814d1c60a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
#1: ffffc900036cc2f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x43e/0x1400 drivers/tty/n_tty.c:2222
=============================================
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 31 Comm: khungtaskd Not tainted 6.16.0-rc6-next-20250718-syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Call Trace:
<TASK>
dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
nmi_cpu_backtrace+0x39e/0x3d0 lib/nmi_backtrace.c:113
nmi_trigger_cpumask_backtrace+0x17a/0x300 lib/nmi_backtrace.c:62
trigger_all_cpu_backtrace include/linux/nmi.h:160 [inline]
check_hung_uninterruptible_tasks kernel/hung_task.c:328 [inline]
watchdog+0xf93/0xfe0 kernel/hung_task.c:491
kthread+0x70e/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
</TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 0 Comm: swapper/1 Not tainted 6.16.0-rc6-next-20250718-syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
RIP: 0010:pv_native_safe_halt+0x13/0x20 arch/x86/kernel/paravirt.c:82
Code: d3 e8 02 00 cc cc cc 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 66 90 0f 00 2d 13 ba 28 00 f3 0f 1e fa fb f4 <c3> cc cc cc cc cc cc cc cc cc cc cc cc 90 90 90 90 90 90 90 90 90
RSP: 0018:ffffc90000197de0 EFLAGS: 000002c2
RAX: eba1d665c07d2f00 RBX: ffffffff8196da38 RCX: eba1d665c07d2f00
RDX: 0000000000000001 RSI: ffffffff8dc6a0fe RDI: ffffffff8c04d400
RBP: ffffc90000197f20 R08: ffff8880b8732f5b R09: 1ffff110170e65eb
R10: dffffc0000000000 R11: ffffed10170e65ec R12: ffffffff8fe3cf30
R13: 0000000000000001 R14: 0000000000000001 R15: 1ffff11003a55b40
FS: 0000000000000000(0000) GS:ffff8881258ab000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000563b2a68e168 CR3: 000000000e338000 CR4: 00000000003526f0
Call Trace:
<TASK>
arch_safe_halt arch/x86/include/asm/paravirt.h:107 [inline]
default_idle+0x13/0x20 arch/x86/kernel/process.c:757
default_idle_call+0x74/0xb0 kernel/sched/idle.c:122
cpuidle_idle_call kernel/sched/idle.c:190 [inline]
do_idle+0x1e8/0x510 kernel/sched/idle.c:330
cpu_startup_entry+0x44/0x60 kernel/sched/idle.c:428
start_secondary+0x101/0x110 arch/x86/kernel/smpboot.c:315
common_startup_64+0x13e/0x147
</TASK>
---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
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