From patchwork Wed Apr 27 19:58:20 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Peter Collingbourne X-Patchwork-Id: 12829463 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 40A23C433F5 for ; Wed, 27 Apr 2022 19:58:29 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id A247C6B0075; Wed, 27 Apr 2022 15:58:28 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 9C8E86B0074; Wed, 27 Apr 2022 15:58:28 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 86FA06B0075; Wed, 27 Apr 2022 15:58:28 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (relay.hostedemail.com [64.99.140.25]) by kanga.kvack.org (Postfix) with ESMTP id 76CBF6B0073 for ; Wed, 27 Apr 2022 15:58:28 -0400 (EDT) Received: from smtpin26.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay11.hostedemail.com (Postfix) with ESMTP id 591B7816F1 for ; Wed, 27 Apr 2022 19:58:28 +0000 (UTC) X-FDA: 79403721096.26.0E34512 Received: from mail-yw1-f202.google.com (mail-yw1-f202.google.com [209.85.128.202]) by imf09.hostedemail.com (Postfix) with ESMTP id 57B17140050 for ; Wed, 27 Apr 2022 19:58:24 +0000 (UTC) Received: by mail-yw1-f202.google.com with SMTP id 00721157ae682-2f4e758e54bso26385247b3.3 for ; Wed, 27 Apr 2022 12:58:27 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=KO6mnAXGVtsbAsRrqxqkdvUTskd4INz5fQ2/DuC94GY=; b=Ybb+mu0NOoj0QhqyLUfK8pV4RJ3NHdJML7DdD1cR9EV1ptUlbNyYiRFI/XT077lown MfQARo0OYRxUjw1C6UpM/ZdDAAbdDiUddgHc2e4MsusWl9yxZiniI1fl9UTzqwLCvepS b/jTz7jX/UryiMBvfHySA+Z7bXgtA7kZEm1gkuQAOE0sSPJ9slqS0OODoAoEEcC9+Cch tr529Szrs7vo6+6iI1JhQHGzNaGd9qua7N2tsk4PpLJcSgKIu/28Z3qZ/JbHNTvWO3qU Tv9w/5M+ql8CfOfBMBZaw4D7LfmnqVQiU+w5I1kLxm1cE+EeL8opw7Q7hF2eQE7kAqqA kqgA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=KO6mnAXGVtsbAsRrqxqkdvUTskd4INz5fQ2/DuC94GY=; b=fMNa+odIme23aLQBegUXuS33WAt6bbbfjRGwBB3dl9bfIKHRSJ1/9e7TRMFxbrDKmn f24/Nbe5XWmwJ4kPEdOAYdvNOzoTM6bQxChxPWAIgl3htThaQScy/CEhtK/rZvHy1Ryr 1hcbKXaiptML6dAVVCE+uu9mMCvcmk1j3/uOFndyz4aalx9uoSP4RtL43lvMaze4TSEi TpUacnsVvV9tAr/ss3saYOLNhOd/hXr0KlbRYNiXqPGsPOu6VmAVTmApM4I2bHnt8sfp Apq5PEvwjsTBaoNHAAnNAQjqp1hus7lqNeYy8QLAkRjSCEOnI0fFZnqjKeCeURLkoBeO 7+JA== X-Gm-Message-State: AOAM531Mo5u5VHYQoDkG/D5QUXp9wTUNXuJD4jqHQtSzXwSZyvGglF9U jXht2xhxm4TRuF7/syLSr2N83W8= X-Google-Smtp-Source: ABdhPJzCu524Ub8WtwbBuF6dltuVfGhjeugFC7wFIIsPODuI/eV7MSubuIdu+U7Bdpq7uVZ2FnFd6PE= X-Received: from pcc-desktop.svl.corp.google.com ([2620:15c:2ce:200:7bf6:862b:86da:9ce1]) (user=pcc job=sendgmr) by 2002:a25:7796:0:b0:645:7353:637a with SMTP id s144-20020a257796000000b006457353637amr26817851ybc.446.1651089507164; Wed, 27 Apr 2022 12:58:27 -0700 (PDT) Date: Wed, 27 Apr 2022 12:58:20 -0700 In-Reply-To: <20220427195820.1716975-1-pcc@google.com> Message-Id: <20220427195820.1716975-2-pcc@google.com> Mime-Version: 1.0 References: <20220427195820.1716975-1-pcc@google.com> X-Mailer: git-send-email 2.36.0.464.gb9c8b46e94-goog Subject: [PATCH v5 2/2] mm: make minimum slab alignment a runtime property From: Peter Collingbourne To: Andrey Konovalov , Hyeonggon Yoo <42.hyeyoo@gmail.com>, Andrew Morton , Catalin Marinas Cc: Peter Collingbourne , Linux ARM , Linux Memory Management List , Linux Kernel Mailing List , vbabka@suse.cz, penberg@kernel.org, roman.gushchin@linux.dev, iamjoonsoo.kim@lge.com, rientjes@google.com, Herbert Xu , Andrey Ryabinin , Alexander Potapenko , Dmitry Vyukov , kasan-dev , Eric Biederman , Kees Cook Authentication-Results: imf09.hostedemail.com; dkim=pass header.d=google.com header.s=20210112 header.b=Ybb+mu0N; spf=pass (imf09.hostedemail.com: domain of 3Y6BpYgMKCGQREEIQQING.EQONKPWZ-OOMXCEM.QTI@flex--pcc.bounces.google.com designates 209.85.128.202 as permitted sender) smtp.mailfrom=3Y6BpYgMKCGQREEIQQING.EQONKPWZ-OOMXCEM.QTI@flex--pcc.bounces.google.com; dmarc=pass (policy=reject) header.from=google.com X-Rspam-User: X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 57B17140050 X-Stat-Signature: gtfosc511tws6gjhxb11iapgd8jzw8yw X-HE-Tag: 1651089504-818787 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: When CONFIG_KASAN_HW_TAGS is enabled we currently increase the minimum slab alignment to 16. This happens even if MTE is not supported in hardware or disabled via kasan=off, which creates an unnecessary memory overhead in those cases. Eliminate this overhead by making the minimum slab alignment a runtime property and only aligning to 16 if KASAN is enabled at runtime. On a DragonBoard 845c (non-MTE hardware) with a kernel built with CONFIG_KASAN_HW_TAGS, waiting for quiescence after a full Android boot I see the following Slab measurements in /proc/meminfo (median of 3 reboots): Before: 169020 kB After: 167304 kB Link: https://linux-review.googlesource.com/id/I752e725179b43b144153f4b6f584ceb646473ead Signed-off-by: Peter Collingbourne Reviewed-by: Andrey Konovalov Reviewed-by: Hyeonggon Yoo <42.hyeyoo@gmail.com> Tested-by: Hyeonggon Yoo <42.hyeyoo@gmail.com> Acked-by: David Rientjes Reviewed-by: Catalin Marinas Acked-by: Vlastimil Babka --- v4: - add a dependent patch to fix the build with CONFIG_JUMP_LABEL disabled v3: - go back to ARCH_SLAB_MINALIGN - revert changes to fs/binfmt_flat.c - update arch_slab_minalign() comment to say that it must be a power of two v2: - use max instead of max_t in flat_stack_align() arch/arm64/include/asm/cache.h | 17 ++++++++++++----- include/linux/slab.h | 12 ++++++++++++ mm/slab.c | 7 +++---- mm/slab_common.c | 3 +-- mm/slob.c | 6 +++--- 5 files changed, 31 insertions(+), 14 deletions(-) diff --git a/arch/arm64/include/asm/cache.h b/arch/arm64/include/asm/cache.h index a074459f8f2f..22b22dc1b1b5 100644 --- a/arch/arm64/include/asm/cache.h +++ b/arch/arm64/include/asm/cache.h @@ -6,6 +6,7 @@ #define __ASM_CACHE_H #include +#include #define CTR_L1IP_SHIFT 14 #define CTR_L1IP_MASK 3 @@ -49,16 +50,22 @@ */ #define ARCH_DMA_MINALIGN (128) +#ifndef __ASSEMBLY__ + +#include +#include + #ifdef CONFIG_KASAN_SW_TAGS #define ARCH_SLAB_MINALIGN (1ULL << KASAN_SHADOW_SCALE_SHIFT) #elif defined(CONFIG_KASAN_HW_TAGS) -#define ARCH_SLAB_MINALIGN MTE_GRANULE_SIZE +static inline size_t arch_slab_minalign(void) +{ + return kasan_hw_tags_enabled() ? MTE_GRANULE_SIZE : + __alignof__(unsigned long long); +} +#define arch_slab_minalign() arch_slab_minalign() #endif -#ifndef __ASSEMBLY__ - -#include - #define ICACHEF_ALIASING 0 #define ICACHEF_VPIPT 1 extern unsigned long __icache_flags; diff --git a/include/linux/slab.h b/include/linux/slab.h index 373b3ef99f4e..2c7190db4cc0 100644 --- a/include/linux/slab.h +++ b/include/linux/slab.h @@ -209,6 +209,18 @@ void kmem_dump_obj(void *object); #define ARCH_SLAB_MINALIGN __alignof__(unsigned long long) #endif +/* + * Arches can define this function if they want to decide the minimum slab + * alignment at runtime. The value returned by the function must be a power + * of two and >= ARCH_SLAB_MINALIGN. + */ +#ifndef arch_slab_minalign +static inline size_t arch_slab_minalign(void) +{ + return ARCH_SLAB_MINALIGN; +} +#endif + /* * kmalloc and friends return ARCH_KMALLOC_MINALIGN aligned * pointers. kmem_cache_alloc and friends return ARCH_SLAB_MINALIGN diff --git a/mm/slab.c b/mm/slab.c index 0edb474edef1..97b756976c8b 100644 --- a/mm/slab.c +++ b/mm/slab.c @@ -3009,10 +3009,9 @@ static void *cache_alloc_debugcheck_after(struct kmem_cache *cachep, objp += obj_offset(cachep); if (cachep->ctor && cachep->flags & SLAB_POISON) cachep->ctor(objp); - if (ARCH_SLAB_MINALIGN && - ((unsigned long)objp & (ARCH_SLAB_MINALIGN-1))) { - pr_err("0x%px: not aligned to ARCH_SLAB_MINALIGN=%d\n", - objp, (int)ARCH_SLAB_MINALIGN); + if ((unsigned long)objp & (arch_slab_minalign() - 1)) { + pr_err("0x%px: not aligned to arch_slab_minalign()=%d\n", objp, + (int)arch_slab_minalign()); } return objp; } diff --git a/mm/slab_common.c b/mm/slab_common.c index 2b3206a2c3b5..33cc49810a54 100644 --- a/mm/slab_common.c +++ b/mm/slab_common.c @@ -154,8 +154,7 @@ static unsigned int calculate_alignment(slab_flags_t flags, align = max(align, ralign); } - if (align < ARCH_SLAB_MINALIGN) - align = ARCH_SLAB_MINALIGN; + align = max_t(size_t, align, arch_slab_minalign()); return ALIGN(align, sizeof(void *)); } diff --git a/mm/slob.c b/mm/slob.c index 40ea6e2d4ccd..3bd2669bd690 100644 --- a/mm/slob.c +++ b/mm/slob.c @@ -478,7 +478,7 @@ static __always_inline void * __do_kmalloc_node(size_t size, gfp_t gfp, int node, unsigned long caller) { unsigned int *m; - int minalign = max_t(size_t, ARCH_KMALLOC_MINALIGN, ARCH_SLAB_MINALIGN); + int minalign = max_t(size_t, ARCH_KMALLOC_MINALIGN, arch_slab_minalign()); void *ret; gfp &= gfp_allowed_mask; @@ -555,7 +555,7 @@ void kfree(const void *block) sp = virt_to_folio(block); if (folio_test_slab(sp)) { - int align = max_t(size_t, ARCH_KMALLOC_MINALIGN, ARCH_SLAB_MINALIGN); + int align = max_t(size_t, ARCH_KMALLOC_MINALIGN, arch_slab_minalign()); unsigned int *m = (unsigned int *)(block - align); slob_free(m, *m + align); } else { @@ -584,7 +584,7 @@ size_t __ksize(const void *block) if (unlikely(!folio_test_slab(folio))) return folio_size(folio); - align = max_t(size_t, ARCH_KMALLOC_MINALIGN, ARCH_SLAB_MINALIGN); + align = max_t(size_t, ARCH_KMALLOC_MINALIGN, arch_slab_minalign()); m = (unsigned int *)(block - align); return SLOB_UNITS(*m) * SLOB_UNIT; }