From patchwork Fri Mar 25 01:11:29 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrew Morton X-Patchwork-Id: 12791158 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5C9D2C433F5 for ; Fri, 25 Mar 2022 01:11:32 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id EFE398D0010; Thu, 24 Mar 2022 21:11:31 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id ED27D8D0005; Thu, 24 Mar 2022 21:11:31 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id D7F008D0010; Thu, 24 Mar 2022 21:11:31 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (relay.a.hostedemail.com [64.99.140.24]) by kanga.kvack.org (Postfix) with ESMTP id C76578D0005 for ; Thu, 24 Mar 2022 21:11:31 -0400 (EDT) Received: from smtpin15.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay02.hostedemail.com (Postfix) with ESMTP id 963D624D24 for ; Fri, 25 Mar 2022 01:11:31 +0000 (UTC) X-FDA: 79281130782.15.E1C3432 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by imf14.hostedemail.com (Postfix) with ESMTP id C67B1100032 for ; Fri, 25 Mar 2022 01:11:30 +0000 (UTC) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 6179A617ED; Fri, 25 Mar 2022 01:11:30 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id B9193C340EC; Fri, 25 Mar 2022 01:11:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1648170689; bh=BGQKIh1lBrcR7nCyFh3Oz52fFiEvIYA+zxKFPH8y99U=; h=Date:To:From:In-Reply-To:Subject:From; b=YOp+bXGG5khbsN9mVzhFMcTy7sZ0G4sZYUb83q4zhh2qcH8WKINdDP+Y0R0iatbRu jAuwQjxYS7ll4ZKUbtPrVE+Aiqf7/YhZJEV8H0k8oWiUhxdSkTBnuKqypDJ71+zYcG uviiUyn9NR7VSlC5p+7OPp0HuPaTCGdgZ48dOTbE= Date: Thu, 24 Mar 2022 18:11:29 -0700 To: will@kernel.org,vincenzo.frascino@arm.com,ryabinin.a.a@gmail.com,pcc@google.com,mark.rutland@arm.com,glider@google.com,eugenis@google.com,elver@google.com,dvyukov@google.com,catalin.marinas@arm.com,andreyknvl@google.com,akpm@linux-foundation.org,patches@lists.linux.dev,linux-mm@kvack.org,mm-commits@vger.kernel.org,torvalds@linux-foundation.org,akpm@linux-foundation.org From: Andrew Morton In-Reply-To: <20220324180758.96b1ac7e17675d6bc474485e@linux-foundation.org> Subject: [patch 058/114] kasan, page_alloc: allow skipping memory init for HW_TAGS Message-Id: <20220325011129.B9193C340EC@smtp.kernel.org> X-Rspam-User: Authentication-Results: imf14.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=korg header.b=YOp+bXGG; spf=pass (imf14.hostedemail.com: domain of akpm@linux-foundation.org designates 139.178.84.217 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org; dmarc=none X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: C67B1100032 X-Stat-Signature: j7yaxdrqunw8if339j91snwriq8qb9y1 X-HE-Tag: 1648170690-605073 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: Andrey Konovalov Subject: kasan, page_alloc: allow skipping memory init for HW_TAGS Add a new GFP flag __GFP_SKIP_ZERO that allows to skip memory initialization. The flag is only effective with HW_TAGS KASAN. This flag will be used by vmalloc code for page_alloc allocations backing vmalloc() mappings in a following patch. The reason to skip memory initialization for these pages in page_alloc is because vmalloc code will be initializing them instead. With the current implementation, when __GFP_SKIP_ZERO is provided, __GFP_ZEROTAGS is ignored. This doesn't matter, as these two flags are never provided at the same time. However, if this is changed in the future, this particular implementation detail can be changed as well. Link: https://lkml.kernel.org/r/0d53efeff345de7d708e0baa0d8829167772521e.1643047180.git.andreyknvl@google.com Signed-off-by: Andrey Konovalov Acked-by: Marco Elver Cc: Alexander Potapenko Cc: Andrey Ryabinin Cc: Catalin Marinas Cc: Dmitry Vyukov Cc: Evgenii Stepanov Cc: Mark Rutland Cc: Peter Collingbourne Cc: Vincenzo Frascino Cc: Will Deacon Signed-off-by: Andrew Morton --- include/linux/gfp.h | 18 +++++++++++------- include/trace/events/mmflags.h | 1 + mm/page_alloc.c | 13 ++++++++++++- 3 files changed, 24 insertions(+), 8 deletions(-) --- a/include/linux/gfp.h~kasan-page_alloc-allow-skipping-memory-init-for-hw_tags +++ a/include/linux/gfp.h @@ -55,14 +55,16 @@ struct vm_area_struct; #define ___GFP_ACCOUNT 0x400000u #define ___GFP_ZEROTAGS 0x800000u #ifdef CONFIG_KASAN_HW_TAGS -#define ___GFP_SKIP_KASAN_UNPOISON 0x1000000u -#define ___GFP_SKIP_KASAN_POISON 0x2000000u +#define ___GFP_SKIP_ZERO 0x1000000u +#define ___GFP_SKIP_KASAN_UNPOISON 0x2000000u +#define ___GFP_SKIP_KASAN_POISON 0x4000000u #else +#define ___GFP_SKIP_ZERO 0 #define ___GFP_SKIP_KASAN_UNPOISON 0 #define ___GFP_SKIP_KASAN_POISON 0 #endif #ifdef CONFIG_LOCKDEP -#define ___GFP_NOLOCKDEP 0x4000000u +#define ___GFP_NOLOCKDEP 0x8000000u #else #define ___GFP_NOLOCKDEP 0 #endif @@ -239,9 +241,10 @@ struct vm_area_struct; * %__GFP_ZERO returns a zeroed page on success. * * %__GFP_ZEROTAGS zeroes memory tags at allocation time if the memory itself - * is being zeroed (either via __GFP_ZERO or via init_on_alloc). This flag is - * intended for optimization: setting memory tags at the same time as zeroing - * memory has minimal additional performace impact. + * is being zeroed (either via __GFP_ZERO or via init_on_alloc, provided that + * __GFP_SKIP_ZERO is not set). This flag is intended for optimization: setting + * memory tags at the same time as zeroing memory has minimal additional + * performace impact. * * %__GFP_SKIP_KASAN_UNPOISON makes KASAN skip unpoisoning on page allocation. * Only effective in HW_TAGS mode. @@ -253,6 +256,7 @@ struct vm_area_struct; #define __GFP_COMP ((__force gfp_t)___GFP_COMP) #define __GFP_ZERO ((__force gfp_t)___GFP_ZERO) #define __GFP_ZEROTAGS ((__force gfp_t)___GFP_ZEROTAGS) +#define __GFP_SKIP_ZERO ((__force gfp_t)___GFP_SKIP_ZERO) #define __GFP_SKIP_KASAN_UNPOISON ((__force gfp_t)___GFP_SKIP_KASAN_UNPOISON) #define __GFP_SKIP_KASAN_POISON ((__force gfp_t)___GFP_SKIP_KASAN_POISON) @@ -261,7 +265,7 @@ struct vm_area_struct; /* Room for N __GFP_FOO bits */ #define __GFP_BITS_SHIFT (24 + \ - 2 * IS_ENABLED(CONFIG_KASAN_HW_TAGS) + \ + 3 * IS_ENABLED(CONFIG_KASAN_HW_TAGS) + \ IS_ENABLED(CONFIG_LOCKDEP)) #define __GFP_BITS_MASK ((__force gfp_t)((1 << __GFP_BITS_SHIFT) - 1)) --- a/include/trace/events/mmflags.h~kasan-page_alloc-allow-skipping-memory-init-for-hw_tags +++ a/include/trace/events/mmflags.h @@ -53,6 +53,7 @@ #ifdef CONFIG_KASAN_HW_TAGS #define __def_gfpflag_names_kasan , \ + {(unsigned long)__GFP_SKIP_ZERO, "__GFP_SKIP_ZERO"}, \ {(unsigned long)__GFP_SKIP_KASAN_POISON, "__GFP_SKIP_KASAN_POISON"}, \ {(unsigned long)__GFP_SKIP_KASAN_UNPOISON, "__GFP_SKIP_KASAN_UNPOISON"} #else --- a/mm/page_alloc.c~kasan-page_alloc-allow-skipping-memory-init-for-hw_tags +++ a/mm/page_alloc.c @@ -2363,10 +2363,21 @@ static inline bool should_skip_kasan_unp return init_tags || (flags & __GFP_SKIP_KASAN_UNPOISON); } +static inline bool should_skip_init(gfp_t flags) +{ + /* Don't skip, if hardware tag-based KASAN is not enabled. */ + if (!kasan_hw_tags_enabled()) + return false; + + /* For hardware tag-based KASAN, skip if requested. */ + return (flags & __GFP_SKIP_ZERO); +} + inline void post_alloc_hook(struct page *page, unsigned int order, gfp_t gfp_flags) { - bool init = !want_init_on_free() && want_init_on_alloc(gfp_flags); + bool init = !want_init_on_free() && want_init_on_alloc(gfp_flags) && + !should_skip_init(gfp_flags); bool init_tags = init && (gfp_flags & __GFP_ZEROTAGS); set_page_private(page, 0);