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=-15.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham 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 0EE41C433B4 for ; Tue, 20 Apr 2021 16:58:28 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 330DA6135F for ; Tue, 20 Apr 2021 16:58:27 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 330DA6135F Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.cz Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 8B1236B006C; Tue, 20 Apr 2021 12:58:26 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 8384F6B006E; Tue, 20 Apr 2021 12:58:26 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 6B2C46B0070; Tue, 20 Apr 2021 12:58:26 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0211.hostedemail.com [216.40.44.211]) by kanga.kvack.org (Postfix) with ESMTP id 4B0486B006C for ; Tue, 20 Apr 2021 12:58:26 -0400 (EDT) Received: from smtpin06.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 06596248D for ; Tue, 20 Apr 2021 16:58:26 +0000 (UTC) X-FDA: 78053353812.06.DF635DA Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) by imf25.hostedemail.com (Postfix) with ESMTP id 7B352600010F for ; Tue, 20 Apr 2021 16:58:22 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 315D7AE5C; Tue, 20 Apr 2021 16:58:24 +0000 (UTC) Subject: Re: [PATCH] mm/slub: use stackdepot to save stack trace in objects To: glittao@gmail.com, cl@linux.com, penberg@kernel.org, rientjes@google.com, iamjoonsoo.kim@lge.com, akpm@linux-foundation.org Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org References: <20210414163434.4376-1-glittao@gmail.com> From: Vlastimil Babka Message-ID: <5eb31e87-f928-9a5a-c937-be748ac3bafa@suse.cz> Date: Tue, 20 Apr 2021 18:58:23 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.9.0 MIME-Version: 1.0 In-Reply-To: <20210414163434.4376-1-glittao@gmail.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 7B352600010F X-Stat-Signature: qzraf636zf9zccztz5o3n83xndj56ghr Received-SPF: none (suse.cz>: No applicable sender policy available) receiver=imf25; identity=mailfrom; envelope-from=""; helo=mx2.suse.de; client-ip=195.135.220.15 X-HE-DKIM-Result: none/none X-HE-Tag: 1618937902-519079 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 4/14/21 6:34 PM, glittao@gmail.com wrote: > From: Oliver Glitta > > Many stack traces are similar so there are many similar arrays. > Stackdepot saves each unique stack only once. > > Replace field addrs in struct track with depot_stack_handle_t handle. > Use stackdepot to save stack trace. > > The benefits are smaller memory overhead and possibility to aggregate > per-cache statistics in the future using the stackdepot handle > instead of matching stacks manually. > > Signed-off-by: Oliver Glitta Reviewed-by: Vlastimil Babka (again with a disclaimer that I'm the advisor of Oliver's student project) > --- > init/Kconfig | 1 + > mm/slub.c | 79 ++++++++++++++++++++++++++++++++-------------------- > 2 files changed, 50 insertions(+), 30 deletions(-) > > diff --git a/init/Kconfig b/init/Kconfig > index 37a17853433a..a4ed2daa6c41 100644 > --- a/init/Kconfig > +++ b/init/Kconfig > @@ -1891,6 +1891,7 @@ config SLUB_DEBUG > default y > bool "Enable SLUB debugging support" if EXPERT > depends on SLUB && SYSFS > + select STACKDEPOT if STACKTRACE_SUPPORT > help > SLUB has extensive debug support features. Disabling these can > result in significant savings in code size. This also disables > diff --git a/mm/slub.c b/mm/slub.c > index 9c0e26ddf300..4b18499726eb 100644 > --- a/mm/slub.c > +++ b/mm/slub.c > @@ -35,6 +35,7 @@ > #include > #include > #include > +#include > > #include > > @@ -203,8 +204,8 @@ static inline bool kmem_cache_has_cpu_partial(struct kmem_cache *s) > #define TRACK_ADDRS_COUNT 16 > struct track { > unsigned long addr; /* Called from address */ > -#ifdef CONFIG_STACKTRACE > - unsigned long addrs[TRACK_ADDRS_COUNT]; /* Called from address */ > +#ifdef CONFIG_STACKDEPOT > + depot_stack_handle_t handle; > #endif > int cpu; /* Was running on cpu */ > int pid; /* Pid context */ > @@ -581,22 +582,27 @@ static struct track *get_track(struct kmem_cache *s, void *object, > return kasan_reset_tag(p + alloc); > } > > +#ifdef CONFIG_STACKDEPOT > +static depot_stack_handle_t save_stack_trace(gfp_t flags) > +{ > + unsigned long entries[TRACK_ADDRS_COUNT]; > + depot_stack_handle_t handle; > + unsigned int nr_entries; > + > + nr_entries = stack_trace_save(entries, ARRAY_SIZE(entries), 4); > + handle = stack_depot_save(entries, nr_entries, flags); > + return handle; > +} > +#endif > + > static void set_track(struct kmem_cache *s, void *object, > enum track_item alloc, unsigned long addr) > { > struct track *p = get_track(s, object, alloc); > > if (addr) { > -#ifdef CONFIG_STACKTRACE > - unsigned int nr_entries; > - > - metadata_access_enable(); > - nr_entries = stack_trace_save(kasan_reset_tag(p->addrs), > - TRACK_ADDRS_COUNT, 3); > - metadata_access_disable(); > - > - if (nr_entries < TRACK_ADDRS_COUNT) > - p->addrs[nr_entries] = 0; > +#ifdef CONFIG_STACKDEPOT > + p->handle = save_stack_trace(GFP_KERNEL); > #endif > p->addr = addr; > p->cpu = smp_processor_id(); > @@ -623,14 +629,19 @@ static void print_track(const char *s, struct track *t, unsigned long pr_time) > > pr_err("%s in %pS age=%lu cpu=%u pid=%d\n", > s, (void *)t->addr, pr_time - t->when, t->cpu, t->pid); > -#ifdef CONFIG_STACKTRACE > +#ifdef CONFIG_STACKDEPOT > { > - int i; > - for (i = 0; i < TRACK_ADDRS_COUNT; i++) > - if (t->addrs[i]) > - pr_err("\t%pS\n", (void *)t->addrs[i]); > - else > - break; > + depot_stack_handle_t handle; > + unsigned long *entries; > + unsigned int nr_entries; > + > + handle = READ_ONCE(t->handle); > + if (!handle) { > + pr_err("object allocation/free stack trace missing\n"); > + } else { > + nr_entries = stack_depot_fetch(handle, &entries); > + stack_trace_print(entries, nr_entries, 0); > + } > } > #endif > } > @@ -4017,18 +4028,26 @@ void kmem_obj_info(struct kmem_obj_info *kpp, void *object, struct page *page) > objp = fixup_red_left(s, objp); > trackp = get_track(s, objp, TRACK_ALLOC); > kpp->kp_ret = (void *)trackp->addr; > -#ifdef CONFIG_STACKTRACE > - for (i = 0; i < KS_ADDRS_COUNT && i < TRACK_ADDRS_COUNT; i++) { > - kpp->kp_stack[i] = (void *)trackp->addrs[i]; > - if (!kpp->kp_stack[i]) > - break; > - } > +#ifdef CONFIG_STACKDEPOT > + { > + depot_stack_handle_t handle; > + unsigned long *entries; > + unsigned int nr_entries; > > - trackp = get_track(s, objp, TRACK_FREE); > - for (i = 0; i < KS_ADDRS_COUNT && i < TRACK_ADDRS_COUNT; i++) { > - kpp->kp_free_stack[i] = (void *)trackp->addrs[i]; > - if (!kpp->kp_free_stack[i]) > - break; > + handle = READ_ONCE(trackp->handle); > + if (handle) { > + nr_entries = stack_depot_fetch(handle, &entries); > + for (i = 0; i < KS_ADDRS_COUNT && i < nr_entries; i++) > + kpp->kp_stack[i] = (void *)entries[i]; > + } > + > + trackp = get_track(s, objp, TRACK_FREE); > + handle = READ_ONCE(trackp->handle); > + if (handle) { > + nr_entries = stack_depot_fetch(handle, &entries); > + for (i = 0; i < KS_ADDRS_COUNT && i < nr_entries; i++) > + kpp->kp_free_stack[i] = (void *)entries[i]; > + } > } > #endif > #endif >