From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 974FDC2D0DB for ; Sun, 26 Jan 2020 20:40:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 68B98206F0 for ; Sun, 26 Jan 2020 20:40:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727107AbgAZUkC (ORCPT ); Sun, 26 Jan 2020 15:40:02 -0500 Received: from smtprelay0186.hostedemail.com ([216.40.44.186]:44314 "EHLO smtprelay.hostedemail.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726144AbgAZUkC (ORCPT ); Sun, 26 Jan 2020 15:40:02 -0500 Received: from filter.hostedemail.com (clb03-v110.bra.tucows.net [216.40.38.60]) by smtprelay05.hostedemail.com (Postfix) with ESMTP id 872C818029128; Sun, 26 Jan 2020 20:40:00 +0000 (UTC) X-Session-Marker: 6A6F6540706572636865732E636F6D X-HE-Tag: sign60_1d0aeddd8281f X-Filterd-Recvd-Size: 6260 Received: from XPS-9350.home (unknown [47.151.135.224]) (Authenticated sender: joe@perches.com) by omf12.hostedemail.com (Postfix) with ESMTPA; Sun, 26 Jan 2020 20:39:59 +0000 (UTC) Message-ID: Subject: Re: [for-next][PATCH 7/7] tracing: Use pr_err() instead of WARN() for memory failures From: Joe Perches To: Steven Rostedt , linux-kernel@vger.kernel.org Cc: Ingo Molnar , Andrew Morton , Dmitry Vyukov Date: Sun, 26 Jan 2020 12:38:55 -0800 In-Reply-To: <20200126192021.350763989@goodmis.org> References: <20200126191932.984391723@goodmis.org> <20200126192021.350763989@goodmis.org> Content-Type: text/plain; charset="ISO-8859-1" User-Agent: Evolution 3.34.1-2 MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, 2020-01-26 at 14:19 -0500, Steven Rostedt wrote: > From: "Steven Rostedt (VMware)" > > As warnings can trigger panics, especially when "panic_on_warn" is set, > memory failure warnings can cause panics and fail fuzz testers that are > stressing memory. > > Create a MEM_FAIL() macro to use instead of WARN() in the tracing code > (perhaps this should be a kernel wide macro?), and use that for memory > failure issues. This should stop failing fuzz tests due to warnings. It looks as if most of these could just be removed instead as there is an existing dump_stack() on failure. > diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c [] > @@ -5459,7 +5459,7 @@ static void __init set_ftrace_early_graph(char *buf, int enable) > struct ftrace_hash *hash; > > hash = alloc_ftrace_hash(FTRACE_HASH_DEFAULT_BITS); > - if (WARN_ON(!hash)) > + if (MEM_FAIL(!hash, "Failed to allocate hash\n")) > return; has dump_stack() > while (buf) { > @@ -6591,7 +6591,7 @@ static void add_to_clear_hash_list(struct list_head *clear_list, > > func = kmalloc(sizeof(*func), GFP_KERNEL); > if (!func) { > - WARN_ONCE(1, "alloc failure, ftrace filter could be stale\n"); > + MEM_FAIL(1, "alloc failure, ftrace filter could be stale\n"); has dump_stack() > diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c [] > @@ -3126,7 +3126,7 @@ static int alloc_percpu_trace_buffer(void) > struct trace_buffer_struct *buffers; > > buffers = alloc_percpu(struct trace_buffer_struct); > - if (WARN(!buffers, "Could not allocate percpu trace_printk buffer")) > + if (MEM_FAIL(!buffers, "Could not allocate percpu trace_printk buffer")) > return -ENOMEM; has dump_stack() > > trace_percpu_buffer = buffers; > @@ -7932,7 +7932,7 @@ static struct dentry *tracing_dentry_percpu(struct trace_array *tr, int cpu) > > tr->percpu_dir = tracefs_create_dir("per_cpu", d_tracer); > > - WARN_ONCE(!tr->percpu_dir, > + MEM_FAIL(!tr->percpu_dir, > "Could not create tracefs directory 'per_cpu/%d'\n", cpu); keep? > return tr->percpu_dir; > @@ -8253,7 +8253,7 @@ create_trace_option_files(struct trace_array *tr, struct tracer *tracer) > for (cnt = 0; opts[cnt].name; cnt++) { > create_trace_option_file(tr, &topts[cnt], flags, > &opts[cnt]); > - WARN_ONCE(topts[cnt].entry == NULL, > + MEM_FAIL(topts[cnt].entry == NULL, > "Failed to create trace option: %s", > opts[cnt].name); > } > @@ -8437,7 +8437,7 @@ static int allocate_trace_buffers(struct trace_array *tr, int size) > #ifdef CONFIG_TRACER_MAX_TRACE > ret = allocate_trace_buffer(tr, &tr->max_buffer, > allocate_snapshot ? size : 1); > - if (WARN_ON(ret)) { > + if (MEM_FAIL(ret, "Failed to allocate trace buffer\n")) { > ring_buffer_free(tr->array_buffer.buffer); > tr->array_buffer.buffer = NULL; > free_percpu(tr->array_buffer.data); > @@ -8726,7 +8726,7 @@ static __init void create_trace_instances(struct dentry *d_tracer) > trace_instance_dir = tracefs_create_instance_dir("instances", d_tracer, > instance_mkdir, > instance_rmdir); > - if (WARN_ON(!trace_instance_dir)) > + if (MEM_FAIL(!trace_instance_dir, "Failed to create instances directory\n")) > return; > } > > @@ -8796,7 +8796,7 @@ init_tracer_tracefs(struct trace_array *tr, struct dentry *d_tracer) > #endif > > if (ftrace_create_function_files(tr, d_tracer)) > - WARN(1, "Could not allocate function filter files"); > + MEM_FAIL(1, "Could not allocate function filter files"); > > #ifdef CONFIG_TRACER_SNAPSHOT > trace_create_file("snapshot", 0644, d_tracer, > @@ -9348,8 +9348,7 @@ __init static int tracer_alloc_buffers(void) > > /* TODO: make the number of buffers hot pluggable with CPUS */ > if (allocate_trace_buffers(&global_trace, ring_buf_size) < 0) { > - printk(KERN_ERR "tracer: failed to allocate ring buffer!\n"); > - WARN_ON(1); > + MEM_FAIL(1, "tracer: failed to allocate ring buffer!\n"); has dump_stack() > goto out_free_savedcmd; > } > > @@ -9422,7 +9421,8 @@ void __init early_trace_init(void) > if (tracepoint_printk) { > tracepoint_print_iter = > kmalloc(sizeof(*tracepoint_print_iter), GFP_KERNEL); > - if (WARN_ON(!tracepoint_print_iter)) > + if (MEM_FAIL(!tracepoint_print_iter, > + "Failed to allocate trace iterator\n")) has dump_stack() > tracepoint_printk = 0; > else > static_key_enable(&tracepoint_printk_key.key); > diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h > index 4812a36affac..6bb64d89c321 100644 > --- a/kernel/trace/trace.h > +++ b/kernel/trace/trace.h > @@ -94,6 +94,18 @@ enum trace_type { > > #include "trace_entries.h" > > +/* Use this for memory failure errors */ > +#define MEM_FAIL(condition, fmt, ...) ({ \ > + static bool __section(.data.once) __warned; \ > + int __ret_warn_once = !!(condition); \ > + \ > + if (unlikely(__ret_warn_once && !__warned)) { \ > + __warned = true; \ > + pr_err("ERROR: " fmt, ##__VA_ARGS__); \ > + } \ > + unlikely(__ret_warn_once); \ > +}) > + > /* > * syscalls are special, and need special handling, this is why > * they are not included in trace_entries.h