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: 12829464 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 A2ABBC433F5 for ; Wed, 27 Apr 2022 19:59:40 +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:References: Mime-Version:Message-Id:In-Reply-To:Date:Reply-To:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Owner; bh=KZ1W4LzP6n7mdPYpqpiW2L9/xrJvmjUo3yTNlWjoeMA=; b=GJYdRX3hLRKdRvrQiHRrW47zjM baFDKm7pv+o028q+U1MWwlMikJaLTe60q1YjBXF1pw/Kgyk6ipw4CQuwVPBn0ivYiOrnXSoLkVZoU /bT7ChtZTXza0LXpC4pMMflp3I0z4o5Kgsu4yi7D4nNOpbQXWZoWQuYL+M422wBzMvK1mMU+/xbpp vFd6KZ8UtvLicJ1EBgVn/HIvVuBLjTqCBoyAYWLV7Uu1rnYDDrmxhIchHXwO9RROmsxAYeZuIqAR8 sGNiVWRhs9YoVnIaAE3aaZ35Doy0FFV4N5o/y74LAHk6LLwh1jIGi6hRwHCDtsSIsSkOhoPlZFyLk UYkiH01Q==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1njno1-003RCg-PB; Wed, 27 Apr 2022 19:58:34 +0000 Received: from mail-yw1-x1149.google.com ([2607:f8b0:4864:20::1149]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1njnny-003R9v-AN for linux-arm-kernel@lists.infradead.org; Wed, 27 Apr 2022 19:58:32 +0000 Received: by mail-yw1-x1149.google.com with SMTP id 00721157ae682-2f84aeb403fso19294157b3.22 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=pNcYd+ceA4jGiTUnMXPvZJ/N7xMirU+pKmjXg3SAYAaP79t4T20GiDr5UPXfaaBAlC wUnAbKqCv/IsGjOnAWEtAhVMroQoO6CkG6Z+gocTxK5RA5MBDS2qxMtPNYD67yUFjSiR ze75hgrreE4g3J/L+Fsje1EBUhk4lg5h6DTSjuXIKcytl1bYlrRmTLynkNBJLotPiBBa WcWMKdoT/z59W1H6sugKnlFjqPbpEu6sEAqhhrKml+9vKhIx4EfRo2AB4viOElUAMHcl ytOTw4YvH7+3SX/dRms6O52LDDek44YZ1V0F1sq92MoE3PUyQWD2xV1vP8T8QoaMQMuE ++3g== X-Gm-Message-State: AOAM532vuyLS3qC1PxzblFjnevsSd7qcjfQjyWgcnj5U72hJXQuJLoxr vgz9soEhQWz4s9YQJjAzXlxcoJU= 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 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220427_125830_398318_748920F8 X-CRM114-Status: GOOD ( 21.09 ) 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 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; }