From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pl1-f174.google.com (mail-pl1-f174.google.com [209.85.214.174]) (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 85EAC6FBF for ; Sun, 22 Sep 2024 09:55:11 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.174 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1726998913; cv=none; b=fUMpmONp+861mf8ldr2GbXJXOxu9qRaXeutTLhe+L3Dh8n3hPadYP3V6tQvhhBd7XHvMi6nL8FsH/yTF0cajfBR62zcU0n1kx0uywxLH3pH8/vjpzjGs9hn/KwtvzZmxEhxg19gUa0Owz0YDoHHD1gXDt6DPFmQCJtyHC5Cl0iA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1726998913; c=relaxed/simple; bh=CeDes7R2LpfAXtOku2fbpjXobwbDrU0kfBqni3o6Stk=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version; b=C8HwkIN12VWQahUEVTrxw0tc2sOPsPQQA2DyzXd7c2MBSAL91lQVid8RXkh9B7k1lmRf0F8FG6LFJebzUAwmsYNm9m0VLLpG40Isj2fJ1hUXsMihUm27FUKaOa19TfRPdAxK7+vto5hMg0L2SNPX/iAFifTUYKmBv5c7nvOEDss= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=NYkQzKbV; arc=none smtp.client-ip=209.85.214.174 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="NYkQzKbV" Received: by mail-pl1-f174.google.com with SMTP id d9443c01a7336-2068a7c9286so34846435ad.1 for ; Sun, 22 Sep 2024 02:55:11 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1726998911; x=1727603711; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=gGhASXP0YGE4ncucrvEzkGeI2BDKX774WZmNjI6QgXQ=; b=NYkQzKbVVq+6jbQwSM397Er/4gyjTJs7g5gWhu8kFluSJf0YcSXYlGTv97SnCily59 xIg8RMuq34Tl4r3Fali/FYvJfmau2qvhMZrniOolTF8fdkRFtohrq98rcj91Xeufus3C tRqLuI7XMW8DNokrctD6FyM6ZhwvOnfVWhYDPF7B5Zadn9gpTd3+YI0bPJgAsFABFoKT iNrgHDv+wIWSU9rXTdidpWxXipN0pqmIaTn1UZLbgpYWVT/3/kcx/YmCtG6m8r6Tz9Om BxeYv6c+jOVvImCWAonkMTM+u+rBjmzRQHw9WnphlZXnWhlmeCvBW/vKwgto7P76Ena3 RDng== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1726998911; x=1727603711; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=gGhASXP0YGE4ncucrvEzkGeI2BDKX774WZmNjI6QgXQ=; b=Kvuo43OnMpBsfet84tZdlKHaEghzbDJ+OUnz7hpfNALltIdutEFcGL4szKvwNEinCy Na0y4/ZpQI2oX57TdhMeCOR6keBMbfP9cw7p+rpJVER0u7ewt6LjnN6ILev1iezJz6Sd EHpa5OQBRUhnFKOvCHKZJ+qnwf7rRJOBLJMPuRIuHYYHM1b+FKCVsdBWLZYlbQ+DkTIo h3peJNWa3bdf9SVKT3MLVh1gWBalqzvPhbv+tZAGWBOEzbJndfbzoTcsRt+MnrTA46Qv +qHVB5hdnV9SbaQeRI8fB+z5Gq7Z3Z8dgkSR053fLNJiEdfnHLJj7fXOcbsjlkRlDbFd vzFQ== X-Gm-Message-State: AOJu0YzEwy61u0r/K4KQ7m8ZWbk6taaID4ppDGCg4QIQM8yZWgIz1qF3 tQ0/LwtALs8580Q/FUj/5JrZY9aY7dBnfRmLsXrjXVtCrY6msMVq X-Google-Smtp-Source: AGHT+IEpbyRywRFf64s8nwAH9zd5Hq67CIGz2ZoafpEw6hajqm3BfXSFfz0CsVyfqgLyPb/cH5v7tQ== X-Received: by 2002:a17:903:24c:b0:207:625:cef1 with SMTP id d9443c01a7336-208d8339e94mr107679625ad.2.1726998910552; Sun, 22 Sep 2024 02:55:10 -0700 (PDT) Received: from localhost ([183.226.245.34]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-20794601083sm118459785ad.71.2024.09.22.02.55.09 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 22 Sep 2024 02:55:10 -0700 (PDT) From: "qiwu.chen" X-Google-Original-From: "qiwu.chen" To: corbet@lwn.net, oleg@redhat.com, mhocko@suse.com, jani.nikula@intel.com, akpm@linux-foundation.org, brauner@kernel.org, paulmck@kernel.org Cc: linux-doc@vger.kernel.org, "qiwu.chen" Subject: [PATCH v3 1/2] panic: add option to dump task maps info in panic_print Date: Sun, 22 Sep 2024 17:55:03 +0800 Message-Id: <20240922095504.7182-1-qiwu.chen@transsion.com> X-Mailer: git-send-email 2.25.1 Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Currently, it's hard to debug panic issues caused by kill init, since there is no debug info from user mode in current panic msg such as the user_regs and maps info. This patch adds an option to dump task maps info in panic_print. Signed-off-by: qiwu.chen --- .../admin-guide/kernel-parameters.txt | 1 + Documentation/admin-guide/sysctl/kernel.rst | 1 + kernel/panic.c | 82 +++++++++++++++++++ 3 files changed, 84 insertions(+) diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 8337d0fed311..f76709deef6c 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -4253,6 +4253,7 @@ bit 5: print all printk messages in buffer bit 6: print all CPUs backtrace (if available in the arch) bit 7: print only tasks in uninterruptible (blocked) state + bit 8: print task maps info *Be aware* that this option may print a _lot_ of lines, so there are risks of losing older messages in the log. Use this option carefully, maybe worth to setup a diff --git a/Documentation/admin-guide/sysctl/kernel.rst b/Documentation/admin-guide/sysctl/kernel.rst index f8bc1630eba0..558e365b76a9 100644 --- a/Documentation/admin-guide/sysctl/kernel.rst +++ b/Documentation/admin-guide/sysctl/kernel.rst @@ -872,6 +872,7 @@ bit 4 print ftrace buffer bit 5 print all printk messages in buffer bit 6 print all CPUs backtrace (if available in the arch) bit 7 print only tasks in uninterruptible (blocked) state +bit 8 print task maps info ===== ============================================ So for example to print tasks and memory info on panic, user can:: diff --git a/kernel/panic.c b/kernel/panic.c index 753d12f4dc8f..5b76ff92a6fc 100644 --- a/kernel/panic.c +++ b/kernel/panic.c @@ -77,6 +77,8 @@ EXPORT_SYMBOL_GPL(panic_timeout); #define PANIC_PRINT_ALL_PRINTK_MSG 0x00000020 #define PANIC_PRINT_ALL_CPU_BT 0x00000040 #define PANIC_PRINT_BLOCKED_TASKS 0x00000080 +#define PANIC_PRINT_TASK_MAPS_INFO 0x00000100 + unsigned long panic_print; ATOMIC_NOTIFIER_HEAD(panic_notifier_list); @@ -208,6 +210,83 @@ void nmi_panic(struct pt_regs *regs, const char *msg) } EXPORT_SYMBOL(nmi_panic); +/* + * This function is called in panic proccess if the PANIC_PRINT_TASK_MAPS_INFO + * flag is specified in panic_print, which is helpful to debug panic issues due + * to an unhandled falut in user mode such as kill init. + */ +static void dump_task_maps_info(struct task_struct *tsk) +{ + struct pt_regs *user_ret = task_pt_regs(tsk); + struct mm_struct *mm = tsk->mm; + struct vm_area_struct *vma; + + if (!mm || !user_mode(user_ret)) + return; + + pr_info("Dump task %s:%d maps start\n", tsk->comm, task_pid_nr(tsk)); + mmap_read_lock(mm); + VMA_ITERATOR(vmi, mm, 0); + for_each_vma(vmi, vma) { + struct file *file = vma->vm_file; + int flags = vma->vm_flags; + unsigned long long pgoff = ((loff_t)vma->vm_pgoff) << PAGE_SHIFT; + struct anon_vma_name *anon_name = NULL; + struct mm_struct *mm = vma->vm_mm; + char buf[256] = {0}; + const char *name = NULL; + + if (mm) + anon_name = anon_vma_name(vma); + + if (file) { + if (anon_name) { + snprintf(buf, sizeof(buf), "[anon_shmem:%s]", anon_name->name); + name = buf; + } else { + char *f_path = d_path(file_user_path(file), buf, sizeof(buf)); + + name = IS_ERR(f_path) ? "?" : f_path; + } + goto print; + } + + if (vma->vm_ops && vma->vm_ops->name) { + name = vma->vm_ops->name(vma); + if (name) + goto print; + } + + name = arch_vma_name(vma); + if (!name) { + if (mm) { + if (vma_is_initial_heap(vma)) + name = "[heap]"; + else if (vma_is_initial_stack(vma)) + name = "[stack]"; + } else + name = "[vdso]"; + + if (anon_name) { + snprintf(buf, sizeof(buf), "[anon:%s]", anon_name->name); + name = buf; + } + } + +print: + if (name) + pr_info("%08lx-%08lx %c%c%c%c %08llx %s\n", + vma->vm_start, vma->vm_end, + flags & VM_READ ? 'r' : '-', + flags & VM_WRITE ? 'w' : '-', + flags & VM_EXEC ? 'x' : '-', + flags & VM_MAYSHARE ? 's' : 'p', + pgoff, name); + } + mmap_read_unlock(mm); + pr_info("Dump task %s:%d maps end\n", tsk->comm, task_pid_nr(tsk)); +} + static void panic_print_sys_info(bool console_flush) { if (console_flush) { @@ -233,6 +312,9 @@ static void panic_print_sys_info(bool console_flush) if (panic_print & PANIC_PRINT_BLOCKED_TASKS) show_state_filter(TASK_UNINTERRUPTIBLE); + + if (panic_print & PANIC_PRINT_TASK_MAPS_INFO) + dump_task_maps_info(current); } void check_panic_on_warn(const char *origin) -- 2.25.1