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=-15.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable 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 46027C433DB for ; Wed, 24 Feb 2021 20:02:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id EC87464F2D for ; Wed, 24 Feb 2021 20:02:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232276AbhBXUBz (ORCPT ); Wed, 24 Feb 2021 15:01:55 -0500 Received: from mail.kernel.org ([198.145.29.99]:54852 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234663AbhBXUBr (ORCPT ); Wed, 24 Feb 2021 15:01:47 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 770CF64F21; Wed, 24 Feb 2021 20:01:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1614196866; bh=/3W9GpPijcVwD4pFLLD3dvWkaLEuJAkhG4fAflBESJc=; h=Date:From:To:Subject:In-Reply-To:From; b=Fvanrqz/WJFFSMTVp9c8j/3AG2MbUux0m+9UWOUoAFUVkFGu0OmjgA/60nLlHSwK8 Py28uKcOlpi0RbAiu1m1lUwDELN6hrkrqDZFjZrIvC/qlBhG/xjAEF2KQzcf3TljBv Q1Zs/LwGBkIK0eQCLhvoIukL+ZEAd5zIh0Rc3xR8= Date: Wed, 24 Feb 2021 12:01:04 -0800 From: Andrew Morton To: akpm@linux-foundation.org, catalin.marinas@arm.com, cl@linux.com, iamjoonsoo.kim@lge.com, johannes.berg@intel.com, linux-mm@kvack.org, mm-commits@vger.kernel.org, penberg@kernel.org, rientjes@google.com, torvalds@linux-foundation.org, vbabka@suse.cz Subject: [patch 017/173] mm/slub: disable user tracing for kmemleak caches by default Message-ID: <20210224200104.pbo4Kya9g%akpm@linux-foundation.org> In-Reply-To: <20210224115824.1e289a6895087f10c41dd8d6@linux-foundation.org> User-Agent: s-nail v14.8.16 Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org From: Johannes Berg Subject: mm/slub: disable user tracing for kmemleak caches by default 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. Link: https://lkml.kernel.org/r/20210113215114.d94efa13ba30.I117b6764e725b3192318bbcf4269b13b709539ae@changeid Signed-off-by: Johannes Berg Acked-by: David Rientjes Acked-by: Catalin Marinas Acked-by: Vlastimil Babka Cc: Christoph Lameter Cc: Pekka Enberg Cc: Joonsoo Kim Signed-off-by: Andrew Morton --- mm/slub.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) --- a/mm/slub.c~mm-slub-disable-user-tracing-for-kmemleak-caches-by-default +++ a/mm/slub.c @@ -1413,6 +1413,15 @@ slab_flags_t kmem_cache_flags(unsigned i size_t len; char *next_block; slab_flags_t block_flags; + slab_flags_t slub_debug_local = slub_debug; + + /* + * If the slab cache is for debugging (e.g. kmemleak) then + * don't store user (stack trace) information by default, + * but let the user enable it via the command line below. + */ + if (flags & SLAB_NOLEAKTRACE) + slub_debug_local &= ~SLAB_STORE_USER; len = strlen(name); next_block = slub_debug_string; @@ -1447,7 +1456,7 @@ slab_flags_t kmem_cache_flags(unsigned i } } - return flags | slub_debug; + return flags | slub_debug_local; } #else /* !CONFIG_SLUB_DEBUG */ static inline void setup_object_debug(struct kmem_cache *s, _