From patchwork Wed Jan 13 16:09:31 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Johannes Berg X-Patchwork-Id: 12017251 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=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 48DA0C433E0 for ; Wed, 13 Jan 2021 16:09:47 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 85F5623435 for ; Wed, 13 Jan 2021 16:09:46 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 85F5623435 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=sipsolutions.net Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id DB5918D0066; Wed, 13 Jan 2021 11:09:45 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id D67348D0061; Wed, 13 Jan 2021 11:09:45 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id C7D6B8D0066; Wed, 13 Jan 2021 11:09:45 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0087.hostedemail.com [216.40.44.87]) by kanga.kvack.org (Postfix) with ESMTP id B179F8D0061 for ; Wed, 13 Jan 2021 11:09:45 -0500 (EST) Received: from smtpin06.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id 767538245571 for ; Wed, 13 Jan 2021 16:09:45 +0000 (UTC) X-FDA: 77701237530.06.loaf17_320ccb92751f Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin06.hostedemail.com (Postfix) with ESMTP id 4F0AB1004D28A for ; Wed, 13 Jan 2021 16:09:45 +0000 (UTC) X-HE-Tag: loaf17_320ccb92751f X-Filterd-Recvd-Size: 2439 Received: from sipsolutions.net (s3.sipsolutions.net [144.76.43.62]) by imf39.hostedemail.com (Postfix) with ESMTP for ; Wed, 13 Jan 2021 16:09:44 +0000 (UTC) Received: by sipsolutions.net with esmtpsa (TLS1.3:ECDHE_X25519__RSA_PSS_RSAE_SHA256__AES_256_GCM:256) (Exim 4.94) (envelope-from ) id 1kziiM-005q3K-Du; Wed, 13 Jan 2021 17:09:42 +0100 From: Johannes Berg To: linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org, Andrew Morton , Catalin Marinas , Johannes Berg Subject: [PATCH] mm/slub: disable user tracing for kmemleak caches Date: Wed, 13 Jan 2021 17:09:31 +0100 Message-Id: <20210113170931.929f808099d2.I117b6764e725b3192318bbcf4269b13b709539ae@changeid> X-Mailer: git-send-email 2.26.2 MIME-Version: 1.0 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: From: Johannes Berg If kmemleak is enabled, it uses a kmem cache for its own objects. These objects are used to hold information kmemleak uses, including a stack trace. If slub_debug is also turned on, each of them has *another* stack trace, so the overhead adds up, and on my tests (on ARCH=um, admittedly) 2/3rds of the allocations end up being doing the stack tracing. Turn off SLAB_STORE_USER if SLAB_NOLEAKTRACE was given, to avoid storing the essentially same data twice. Signed-off-by: Johannes Berg --- Perhaps instead it should go the other way around, and kmemleak could even use/access the stack trace that's already in there ... But I don't really care too much, I can just turn off slub debug for the kmemleak caches via the command line anyway :-) --- mm/slub.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/mm/slub.c b/mm/slub.c index 34dcc09e2ec9..625a32a6645b 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -1446,7 +1446,16 @@ slab_flags_t kmem_cache_flags(unsigned int object_size, } } - return flags | slub_debug; + flags |= slub_debug; + + /* + * If the slab cache is for debugging (e.g. kmemleak) then + * don't store user (stack trace) information. + */ + if (flags & SLAB_NOLEAKTRACE) + flags &= ~SLAB_STORE_USER; + + return flags; } #else /* !CONFIG_SLUB_DEBUG */ static inline void setup_object_debug(struct kmem_cache *s,