From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-oa2-f1.google.com (mail-oa2-f1.google.com [74.125.231.65]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2B68441A4E4 for ; Mon, 31 Aug 2026 14:16:53 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=74.125.231.65 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788185816; cv=none; b=GPyF9SvhxGRcqhedjh7orz1/n85iW0QbfG5OhoHhZhgmhs0yiZn9NKG+QWjcKAmHNyP/j4GjtjcuDYEKacaC5vDghcRW9ga183XuJcEKTaqQ0BK99C5N2m4Be5SWB611+A4qlo2JVCmzKSYrYDJTn3Pr22qXjXPKkPSNJ29N+3s= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788185816; c=relaxed/simple; bh=5J8+h2X+UJ765NJnkaf379tWFSjm61zrbLkTZbYFUz0=; h=MIME-Version:Date:Message-ID:Subject:From:To:Content-Type; b=Ku4yl0By7W4lpgwULx2P0dv7QHvnSGtBqqILhCWA1tnYeb4kB8fGhTkDu0wfR7I/s4YpV6xUmGlTBu5M3IovBZ5kP5Zrd7I8D7L8+WCTnmYLuIhhFYYGTl3wivTS8COHlyVCFnfaQ/gQ8x9p3rFbNf3jfqUpMwtMU+chPDggAzU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=syzkaller.appspotmail.com; spf=pass smtp.mailfrom=M3KW2WVRGUFZ5GODRSRYTGD7.apphosting.bounces.google.com; arc=none smtp.client-ip=74.125.231.65 Authentication-Results: smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=syzkaller.appspotmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=M3KW2WVRGUFZ5GODRSRYTGD7.apphosting.bounces.google.com Received: by mail-oa2-f1.google.com with SMTP id 586e51a60fabf-448a12ddfb4so2117437fac.1 for ; Mon, 31 Aug 2026 07:16:53 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1788185813; x=1788790613; h=content-type:to:from:subject:message-id:date:mime-version :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to :content-type; bh=b1EW2CJOojbKHZ9ZhywIovdwExeL64GkrcTsZeJGyWM=; b=TScB3qAWvk2ww6k8TGnyFMvzyGGFiJ6XEZ7SqIobu34qw0/KlUrEo7SRzExqxDG53w T4gV7teSzzmjOGRABdTTrosQZrg1ggV/wr1oYK+uu7ALbI2nSO6O0kdqK29k38+LSL/m zWz+u7h6etwBJC9WYqIRpTMhFcn+LsZ8FON3yBx91aTaWa/tPkXm9XPQhsPhAi8PdT0S qohvg9OJVLAe5tqbYYl+UhyJupG305SYqAviBxoNdPMY0Jh10AtITri3KH3mVv5lrijC XWvcZ904KQsYiZUwCxPXvPJlmpXlzTsCEKO/IofyP6xETr/Mz5li84UTpVhE4K4TyoS0 1rew== X-Forwarded-Encrypted: i=1; AHgh+RoHD+sPL0N/s2PmfjjNfvKcQ42FapIZL0+yFazxg0myN/x9OalB7sjOcqsD51xeaR6LPy1PrgIAI15rx18=@vger.kernel.org X-Gm-Message-State: AFuF++lnROGGS4JIPdkP2s7h96niiwhoq2kryjN4UrIK/47XKp6X9sSe CRNNpAkUaeGpsLK++9E+CWPrBranaxqddc0vhmLjywzTy0qqCY9Mj+sM/0viXPwbwcNvFFBUw2X yMIxFE3FheD3WmqYuO9DEDZ8KfjNUPTZBtpgGz5/ajvFJsEJll0nuZQjzrps= Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Received: by 2002:a05:6808:14c4:b0:4a3:fb6c:9adf with SMTP id 5614622812f47-4b5b8198937mr1343976b6e.12.1788185812994; Mon, 31 Aug 2026 07:16:52 -0700 (PDT) Date: Mon, 31 Aug 2026 07:16:52 -0700 X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <6a958cd4.a8e469d2.cbf3.561d.GAE@google.com> Subject: [syzbot] [kvm?] INFO: task hung in kvm_gmem_release From: syzbot To: david@kernel.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, pbonzini@redhat.com, seanjc@google.com, syzkaller-bugs@googlegroups.com Content-Type: text/plain; charset="UTF-8" Hello, syzbot found the following issue on: HEAD commit: 08dbfad3f504 Merge tag 'for-linus' of git://git.kernel.org.. git tree: upstream console+strace: https://syzkaller.appspot.com/x/log.txt?x=12ee0349580000 kernel config: https://syzkaller.appspot.com/x/.config?x=5e4e3a0e188a497e dashboard link: https://syzkaller.appspot.com/bug?extid=6895ff73d58c59e653ba compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1153ee25580000 Downloadable assets: disk image: https://storage.googleapis.com/syzbot-assets/ddff5719ec3b/disk-08dbfad3.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/4b5e39b20fa5/vmlinux-08dbfad3.xz kernel image: https://storage.googleapis.com/syzbot-assets/eb1f70eed57f/bzImage-08dbfad3.xz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+6895ff73d58c59e653ba@syzkaller.appspotmail.com INFO: task syz.0.17:6104 blocked for more than 143 seconds. Not tainted syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:syz.0.17 state:D stack:25544 pid:6104 tgid:6104 ppid:5900 task_flags:0x400040 flags:0x00080003 Call Trace: context_switch kernel/sched/core.c:5520 [inline] __schedule+0x17d4/0x5820 kernel/sched/core.c:7270 __schedule_loop kernel/sched/core.c:7347 [inline] schedule+0x164/0x2b0 kernel/sched/core.c:7362 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7419 __mutex_lock+0 __mutex_lock_common kernel/locking/mutex.c:726 [inline] __mutex_lock+0x7c1/0x1550 kernel/locking/mutex.c:821 kvm_gmem_release+0xdf/0x3e0 virt/kvm/guest_memfd.c:310 __fput+0x418/0xa50 fs/file_table.c:512 task_work_run+0x1d9/0x270 kernel/task_work.c:233 ptrace_notify+0x27c/0x2b0 kernel/signal.c:2524 ptrace_report_syscall include/linux/ptrace.h:416 [inline] ptrace_report_syscall_exit+0x2d/0x50 include/linux/ptrace.h:477 arch_ptrace_report_syscall_exit include/linux/entry-common.h:233 [inline] syscall_exit_work include/linux/entry-common.h:266 [inline] syscall_exit_to_user_mode_work include/linux/entry-common.h:297 [inline] syscall_exit_to_user_mode include/linux/entry-common.h:334 [inline] do_syscall_64+0x4a0/0x520 arch/x86/entry/syscall_64.c:89 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f625079e159 RSP: 002b:00007ffd1d739348 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4 RAX: 0000000000000000 RBX: 00007f6250a27da0 RCX: 00007f625079e159 RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003 RBP: 00007f6250a27da0 R08: 0000000000000006 R09: 0000000000000000 R10: 00007f6250a27cb0 R11: 0000000000000246 R12: 00000000000277b3 R13: 00007f6250a2609c R14: 0000000000027546 R15: 00007ffd1d739450 Showing all locks held in the system: locks held by pr/ttyS0/16: 2, last CPU#1: #0: ffffffff8ec362b8 (console_srcu){....}-{0:0}, at: rcu_try_lock_acquire include/linux/rcupdate.h:314 [inline] #0: ffffffff8ec362b8 (console_srcu){....}-{0:0}, at: srcu_read_lock_nmisafe include/linux/srcu.h:439 [inline] #0: ffffffff8ec362b8 (console_srcu){....}-{0:0}, at: console_srcu_read_lock+0x30/0x60 kernel/printk/printk.c:291 #1: ffffffff9ad2f098 (&port_lock_key){-...}-{3:3}, at: __uart_port_lock_irqsave include/linux/serial_core.h:613 [inline] #1: ffffffff9ad2f098 (&port_lock_key){-...}-{3:3}, at: univ8250_console_device_lock+0x67/0xc0 drivers/tty/serial/8250/8250_core.c:413 locks held by khungtaskd/32: 1, last CPU#0: #0: ffffffff8ed5c6e0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline] #0: ffffffff8ed5c6e0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline] #0: ffffffff8ed5c6e0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6837 locks held by getty/5374: 2, on CPU#0: #0: ffff8880325cd0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243 #1: ffffc900032332e8 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x45a/0x1360 drivers/tty/n_tty.c:2211 locks held by syz.0.17/6104: 1, on CPU#1: #0: ffff88807bb840a0 (&kvm->slots_lock){+.+.}-{4:4}, at: kvm_gmem_release+0xdf/0x3e0 virt/kvm/guest_memfd.c:310 locks held by syz.0.17/6106: 1, last CPU#0: #0: ffff88807bb840a0 (&kvm->slots_lock){+.+.}-{4:4}, at: kvm_vm_set_mem_attributes virt/kvm/kvm_main.c:2566 [inline] #0: ffff88807bb840a0 (&kvm->slots_lock){+.+.}-{4:4}, at: kvm_vm_ioctl_set_mem_attributes+0x33c/0x1600 virt/kvm/kvm_main.c:2625 locks held by syz.1.18/6149: 1, on CPU#1: #0: ffff8880334a80a0 (&kvm->slots_lock){+.+.}-{4:4}, at: kvm_gmem_release+0xdf/0x3e0 virt/kvm/guest_memfd.c:310 locks held by syz.1.18/6151: 3, last CPU#0: #0: ffff8880334a80a0 (&kvm->slots_lock){+.+.}-{4:4}, at: kvm_vm_set_mem_attributes virt/kvm/kvm_main.c:2566 [inline] #0: ffff8880334a80a0 (&kvm->slots_lock){+.+.}-{4:4}, at: kvm_vm_ioctl_set_mem_attributes+0x33c/0x1600 virt/kvm/kvm_main.c:2625 #1: ffffffff8ee8f900 (fs_reclaim){+.+.}-{0:0}, at: might_alloc include/linux/sched/mm.h:316 [inline] #1: ffffffff8ee8f900 (fs_reclaim){+.+.}-{0:0}, at: xa_cmpxchg include/linux/xarray.h:697 [inline] #1: ffffffff8ee8f900 (fs_reclaim){+.+.}-{0:0}, at: xa_reserve include/linux/xarray.h:1088 [inline] #1: ffffffff8ee8f900 (fs_reclaim){+.+.}-{0:0}, at: kvm_vm_set_mem_attributes virt/kvm/kvm_main.c:2577 [inline] #1: ffffffff8ee8f900 (fs_reclaim){+.+.}-{0:0}, at: kvm_vm_ioctl_set_mem_attributes+0x3a1/0x1600 virt/kvm/kvm_main.c:2625 #2: ffffffff8eea5560 (mmu_notifier_invalidate_range_start){+.+.}-{0:0}, at: fs_reclaim_acquire+0x7c/0x100 mm/page_alloc.c:4392 locks held by syz.2.19/6189: 1, on CPU#0: #0: ffff88807f99c0a0 (&kvm->slots_lock){+.+.}-{4:4}, at: kvm_gmem_release+0xdf/0x3e0 virt/kvm/guest_memfd.c:310 locks held by syz.2.19/6191: 1, last CPU#0: #0: ffff88807f99c0a0 (&kvm->slots_lock){+.+.}-{4:4}, at: kvm_vm_set_mem_attributes virt/kvm/kvm_main.c:2566 [inline] #0: ffff88807f99c0a0 (&kvm->slots_lock){+.+.}-{4:4}, at: kvm_vm_ioctl_set_mem_attributes+0x33c/0x1600 virt/kvm/kvm_main.c:2625 locks held by syz.3.20/6228: 1, on CPU#1: #0: ffff888035a6c0a0 (&kvm->slots_lock){+.+.}-{4:4}, at: kvm_gmem_release+0xdf/0x3e0 virt/kvm/guest_memfd.c:310 locks held by syz.3.20/6230: 1, last CPU#1: #0: ffff888035a6c0a0 (&kvm->slots_lock){+.+.}-{4:4}, at: kvm_vm_set_mem_attributes virt/kvm/kvm_main.c:2566 [inline] #0: ffff888035a6c0a0 (&kvm->slots_lock){+.+.}-{4:4}, at: kvm_vm_ioctl_set_mem_attributes+0x33c/0x1600 virt/kvm/kvm_main.c:2625 locks held by syz.4.22/6283: 1, on CPU#0: #0: ffff8880781540a0 (&kvm->slots_lock){+.+.}-{4:4}, at: kvm_gmem_release+0xdf/0x3e0 virt/kvm/guest_memfd.c:310 locks held by syz.4.22/6285: 1, last CPU#1: #0: ffff8880781540a0 (&kvm->slots_lock){+.+.}-{4:4}, at: kvm_vm_set_mem_attributes virt/kvm/kvm_main.c:2566 [inline] #0: ffff8880781540a0 (&kvm->slots_lock){+.+.}-{4:4}, at: kvm_vm_ioctl_set_mem_attributes+0x33c/0x1600 virt/kvm/kvm_main.c:2625 locks held by syz.5.23/6331: 1, on CPU#0: #0: ffff88802c2340a0 (&kvm->slots_lock){+.+.}-{4:4}, at: kvm_gmem_release+0xdf/0x3e0 virt/kvm/guest_memfd.c:310 locks held by syz.5.23/6333: 1, last CPU#1: #0: ffff88802c2340a0 (&kvm->slots_lock){+.+.}-{4:4}, at: kvm_vm_set_mem_attributes virt/kvm/kvm_main.c:2566 [inline] #0: ffff88802c2340a0 (&kvm->slots_lock){+.+.}-{4:4}, at: kvm_vm_ioctl_set_mem_attributes+0x33c/0x1600 virt/kvm/kvm_main.c:2625 ============================================= NMI backtrace for cpu 0 CPU: 0 UID: 0 PID: 32 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026 Call Trace: dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120 nmi_cpu_backtrace+0x274/0x2d0 lib/nmi_backtrace.c:123 nmi_trigger_cpumask_backtrace+0x17d/0x390 lib/nmi_backtrace.c:66 trigger_all_cpu_backtrace include/linux/nmi.h:164 [inline] __sys_info lib/sys_info.c:157 [inline] sys_info+0x135/0x170 lib/sys_info.c:165 check_hung_uninterruptible_tasks kernel/hung_task.c:353 [inline] watchdog+0xfd7/0x1030 kernel/hung_task.c:561 kthread+0x38b/0x480 kernel/kthread.c:436 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 UID: 0 PID: 16 Comm: pr/ttyS0 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026 RIP: 0010:io_serial_in+0x77/0xc0 drivers/tty/serial/8250/8250_port.c:409 Code: e8 4e e8 55 fc 44 89 f9 d3 e3 49 83 c6 40 4c 89 f0 48 c1 e8 03 42 80 3c 20 00 74 08 4c 89 f7 e8 1f b0 c5 fc 41 03 1e 89 da ec <0f> b6 c0 5b 41 5c 41 5e 41 5f e9 5a cc 74 06 cc 44 89 f9 80 e1 07 RSP: 0018:ffffc900001578b8 EFLAGS: 00000002 RAX: 1ffffffff35a5e00 RBX: 00000000000003fd RCX: 0000000000000000 RDX: 00000000000003fd RSI: 0000000000000000 RDI: 0000000000000020 RBP: dffffc0000000000 R08: 0000000000000003 R09: 0000000000000004 R10: dffffc0000000000 R11: ffffffff8571cb00 R12: dffffc0000000000 R13: 0000000000000000 R14: ffffffff9ad2f0c0 R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffff888124ddc000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000557adc994a38 CR3: 00000000772ec000 CR4: 00000000003526f0 Call Trace: serial_in drivers/tty/serial/8250/8250.h:128 [inline] serial_lsr_in drivers/tty/serial/8250/8250.h:150 [inline] wait_for_lsr+0x184/0x2f0 drivers/tty/serial/8250/8250_port.c:2013 serial8250_fifo_wait_for_lsr_thre drivers/tty/serial/8250/8250_port.c:3270 [inline] __serial8250_console_fifo_write+0xcd/0x3e0 drivers/tty/serial/8250/8250_port.c:3345 serial8250_console_fifo_write drivers/tty/serial/8250/8250_port.c:3378 [inline] __serial8250_console_write drivers/tty/serial/8250/8250_port.c:3429 [inline] serial8250_console_write+0xaa1/0x1200 drivers/tty/serial/8250/8250_port.c:3493 nbcon_emit_next_record+0xef5/0x1a90 kernel/printk/nbcon.c:-1 nbcon_emit_one kernel/printk/nbcon.c:1157 [inline] nbcon_kthread_func+0x679/0x880 kernel/printk/nbcon.c:1271 kthread+0x38b/0x480 kernel/kthread.c:436 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 --- This report is generated by a bot. It may contain errors. See https://goo.gl/tpsmEJ for more information about syzbot. syzbot engineers can be reached at syzkaller@googlegroups.com. syzbot will keep track of this issue. See: https://goo.gl/tpsmEJ#status for how to communicate with syzbot. If the report is already addressed, let syzbot know by replying with: #syz fix: exact-commit-title 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. If you want to overwrite report's subsystems, reply with: #syz set subsystems: new-subsystem (See the list of subsystem names on the web dashboard) If the report is a duplicate of another one, reply with: #syz dup: exact-subject-of-another-report If you want to undo deduplication, reply with: #syz undup