From patchwork Fri Apr 22 20:18:30 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Peter Collingbourne X-Patchwork-Id: 12824064 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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id A8639C433F5 for ; Fri, 22 Apr 2022 20:20:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:Cc:To:From:Subject:Mime-Version: Message-Id:Date:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To: References:List-Owner; bh=mh7tLOhtHd9v77sIR/IGTpVk6F3URRs1uvhn0LmKBAM=; b=DEd cFxe9g9AcGMJxDbYkJtHRUR3HL2EzIgHS0OXWq4ubR3Y/h9A7s+olTm5vNnwHdvH2pdn2ksWFf4rd 8jgIIssYCM/+r+FsiCdY5rCj1RF5d6vNvK/0B/zr36KniOL5J0iPwAXgltp5hqfrAfNMXgW/3OJeA iCUGMqh3f9flBIV60ElPpdWCO5618GDtS/1S20v9E0NMVS9WdO8RNSdD3xIu2dMedmcXepEzmzSil mL151t32O1c3YnDZRzIgi1I0uqdHJbxNczempKlMiH9wCZFwu6lM0uOe+F2P89JAxUsf30P4pihGQ vnXPdZ2LLRMFHkyH2NTsNAtkZdNx1Pg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1nhzjs-002Do6-Gf; Fri, 22 Apr 2022 20:18:48 +0000 Received: from mail-yb1-xb4a.google.com ([2607:f8b0:4864:20::b4a]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1nhzjo-002DnI-N5 for linux-arm-kernel@lists.infradead.org; Fri, 22 Apr 2022 20:18:46 +0000 Received: by mail-yb1-xb4a.google.com with SMTP id x7-20020a056902050700b00641671dc5d0so8086161ybs.18 for ; Fri, 22 Apr 2022 13:18:41 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=date:message-id:mime-version:subject:from:to:cc; bh=eMAERF62YTPWtGAsO2YVmQloDH5oUr4o6LySCLx0+Cc=; b=F83iESBWnyy6uOnOgeXvhunYpfwEIKcvbOdsfG8Cp6juORqTB5/nyhOk7YWhV15WRD mj/4LWY3xVAfwCdPVkSCNFayj1T36VLUNCxX90pH1FGwsgJKnEql6zrzfIjrQcGdVqLO yw7SVLcseqko8s7na0HZRF6ZmLyDMnO92X2a/jpzJ0ZxcdbuEr0jyUfppc0XxYFFkMZi OlDE09MJDkJ8B4l+ofc7oi+3/oizqB0UL2V0Qctf6ujyteRiJdRTU/qWsbiBdom3DsPT l7G/2dY47aoouvl5TMBEVo7BKXknk054vhzlwt3Y5foEZctZ65TFJ9m3Y+EEbkBK8EhX +vCQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:message-id:mime-version:subject:from:to:cc; bh=eMAERF62YTPWtGAsO2YVmQloDH5oUr4o6LySCLx0+Cc=; b=PNTYoK/94Ehug5iq3G2HLrHhdS5liWaUh4g/UQBYvb85KTMkVLgHQgQJqjT0Rr4dqb vIWVRWkHGu1f8dHV3AWiMeG6nWAU/lMIEGocjyRBszXxFuqiS7aOkVHsLbWoEN7aslNA 3K0TCnZdxbAzmkg2VA3FXLq0a5hjz+Eb//v9chupPIAbwYIT3Bzct9wkMO19Wr/rujbY LuE1hyZNwPsAQzAGDM91ixz3xrfL4Uf5YArcVL1uUiDu792RNdmpuiW0SLov+cyu6ELB e9VPRsPzUxmWb6TqPRE6Z+2S74f2CkfA44Lu4zQq2IbLwsdaHpQlTIQihHMxA9MUU3Wc uKfA== X-Gm-Message-State: AOAM532kC/vnsWTWHonzCJOrDL+7VD3xXQ2jbiYH8C9GJL7Hg6YTDokr Gj4mncw4MGzdLszebx4WcIcyUPo= X-Google-Smtp-Source: ABdhPJzs3wUmGnm/6gjGMkcBDBSkTa9dTxn95pedDMqZb3BCTfFfhpQ/gQ6c3EzTP1AHdexsjK2ZhLU= X-Received: from pcc-desktop.svl.corp.google.com ([2620:15c:2ce:200:b874:60b4:62b:9c7a]) (user=pcc job=sendgmr) by 2002:a81:2654:0:b0:2f7:c5f4:a486 with SMTP id m81-20020a812654000000b002f7c5f4a486mr265675ywm.141.1650658720646; Fri, 22 Apr 2022 13:18:40 -0700 (PDT) Date: Fri, 22 Apr 2022 13:18:30 -0700 Message-Id: <20220422201830.288018-1-pcc@google.com> Mime-Version: 1.0 X-Mailer: git-send-email 2.36.0.rc2.479.g8af0fa9b8e-goog Subject: [PATCH v3] 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 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220422_131844_780032_C5339D98 X-CRM114-Status: GOOD ( 19.82 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org 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 Reported-by: kernel test robot Reviewed-by: Catalin Marinas --- 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; }