From patchwork Wed Feb 17 20:56:32 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrey Konovalov X-Patchwork-Id: 12092337 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=-16.5 required=3.0 tests=BAYES_00, DKIM_ADSP_CUSTOM_MED,DKIM_INVALID,DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT autolearn=ham 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 84C1BC433E0 for ; Wed, 17 Feb 2021 20:56:57 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id DB51B64D5D for ; Wed, 17 Feb 2021 20:56:56 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org DB51B64D5D Authentication-Results: mail.kernel.org; dmarc=fail (p=reject dis=none) header.from=google.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 6B0266B0006; Wed, 17 Feb 2021 15:56:56 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 660EA6B006C; Wed, 17 Feb 2021 15:56:56 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 528B86B006E; Wed, 17 Feb 2021 15:56:56 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0047.hostedemail.com [216.40.44.47]) by kanga.kvack.org (Postfix) with ESMTP id 38E886B0006 for ; Wed, 17 Feb 2021 15:56:56 -0500 (EST) Received: from smtpin01.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id F042F184C215F for ; Wed, 17 Feb 2021 20:56:55 +0000 (UTC) X-FDA: 77828969190.01.BC333ED Received: from mail-wr1-f74.google.com (mail-wr1-f74.google.com [209.85.221.74]) by imf29.hostedemail.com (Postfix) with ESMTP id 7CC28DC for ; Wed, 17 Feb 2021 20:56:55 +0000 (UTC) Received: by mail-wr1-f74.google.com with SMTP id p11so17686365wrm.13 for ; Wed, 17 Feb 2021 12:56:55 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=sender:date:message-id:mime-version:subject:from:to:cc; bh=SFShG9HSiA/a5wZPjw/2OI6suzBuDo/vPg1sGXiNPU4=; b=uq+kvVIzeR3An4gN/CAYw6QE6pVQHn27D86IFwunejdmU2OjZaTb9XiR41vGvWVf1m DksVLOj8BdFHTVsw2bj45IJjx43mEoGKUZA6z2RJ8uqSk/sjjs9qy/YvYTfc78kfmHKw ur3Pwdw66rmu5Fo43k0P81tGop/9P/X9cep/Alz9YOKrijW7UIjvvnikPc5vPke+4zXc oBsnCBHRKMjugKkcpV4PRP1ZwVB352IYfVqSk6lqqJtCp2DNfCCl0Fi3P+J0Ydy/z84l cXjO9FMDbiHmosEuqU9+ZzFuSrBXaRZ+eUr4rk9bU5OtGytxWDGj7MwqEkWhh+/Uyc5Q ADNA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:date:message-id:mime-version:subject:from :to:cc; bh=SFShG9HSiA/a5wZPjw/2OI6suzBuDo/vPg1sGXiNPU4=; b=TvMUDIqG7DJPkN1bhKxI2a7guW2HufC6SE84R9ZVEFzbOAzxvmwG3eZbyNeWVgTsyT 0zgZzQyMoCONF4b44/+la2ZCYAGx5+LHmULIuT5swLz2A4kpGyBxU431fVIpvqR9wLtP l98ccz4w19GAV4gGbKMigaF/wPnjPAqeOdJYait4L7YBZ5oy7E/VyCNF+IGhtIc5Edou TaVDOBclV5pzKfmtxz053RgW9Iw8NWwopqz7MlBxxcHR6uud9kcrsn3Ty0dDLdfIzIKG GpQmmaGPb4uqmxaksCCrEYTOM7OsSplMaNa3uc+Hf7jdERpHUgjkw4T3+r7jShXbT2dY fMEQ== X-Gm-Message-State: AOAM531H6bcjVEPqbuMwtdN5htgXbIt+6jT0zZiMuiq/LEvwlxURX5P8 M+MUCiuqA3npUJyKsBozKkWhpjCL84xqIDD/ X-Google-Smtp-Source: ABdhPJzpzJFCBeHD/qAy4KRbvT1c+dX2xurE+gdmzIVLGnbTZurQCDQ/kd3T+GmwRfTjrwYjKetpJ1RUziqKPKwg X-Received: from andreyknvl3.muc.corp.google.com ([2a00:79e0:15:13:fc35:c4d:59c2:bb21]) (user=andreyknvl job=sendgmr) by 2002:a05:600c:4314:: with SMTP id p20mr604956wme.52.1613595413677; Wed, 17 Feb 2021 12:56:53 -0800 (PST) Date: Wed, 17 Feb 2021 21:56:32 +0100 Message-Id: <487751e1ccec8fcd32e25a06ce000617e96d7ae1.1613595269.git.andreyknvl@google.com> Mime-Version: 1.0 X-Mailer: git-send-email 2.30.0.478.g8a0d178c01-goog Subject: [PATCH] mm, kasan: don't poison boot memory From: Andrey Konovalov To: Andrew Morton , Catalin Marinas , Vincenzo Frascino Cc: Will Deacon , Dmitry Vyukov , Andrey Ryabinin , Alexander Potapenko , Marco Elver , Peter Collingbourne , Evgenii Stepanov , Branislav Rankov , Kevin Brodsky , Christoph Hellwig , kasan-dev@googlegroups.com, linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrey Konovalov X-Stat-Signature: qnzxa57uia6josxdfy6jh1uh58d4srd7 X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 7CC28DC Received-SPF: none (flex--andreyknvl.bounces.google.com>: No applicable sender policy available) receiver=imf29; identity=mailfrom; envelope-from="<3FYMtYAoKCNg4H7L8SEHPFAIIAF8.6IGFCHOR-GGEP46E.ILA@flex--andreyknvl.bounces.google.com>"; helo=mail-wr1-f74.google.com; client-ip=209.85.221.74 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1613595415-7033 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: During boot, all non-reserved memblock memory is exposed to the buddy allocator. Poisoning all that memory with KASAN lengthens boot time, especially on systems with large amount of RAM. This patch makes page_alloc to not call kasan_free_pages() on all new memory. __free_pages_core() is used when exposing fresh memory during system boot and when onlining memory during hotplug. This patch adds a new FPI_SKIP_KASAN_POISON flag and passes it to __free_pages_ok() through free_pages_prepare() from __free_pages_core(). This has little impact on KASAN memory tracking. Assuming that there are no references to newly exposed pages before they are ever allocated, there won't be any intended (but buggy) accesses to that memory that KASAN would normally detect. However, with this patch, KASAN stops detecting wild and large out-of-bounds accesses that happen to land on a fresh memory page that was never allocated. This is taken as an acceptable trade-off. All memory allocated normally when the boot is over keeps getting poisoned as usual. Signed-off-by: Andrey Konovalov Change-Id: Iae6b1e4bb8216955ffc14af255a7eaaa6f35324d --- mm/page_alloc.c | 43 ++++++++++++++++++++++++++++++++----------- 1 file changed, 32 insertions(+), 11 deletions(-) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 0b55c9c95364..f10966e3b4a5 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -108,6 +108,17 @@ typedef int __bitwise fpi_t; */ #define FPI_TO_TAIL ((__force fpi_t)BIT(1)) +/* + * Don't poison memory with KASAN. + * During boot, all non-reserved memblock memory is exposed to the buddy + * allocator. Poisoning all that memory lengthens boot time, especially on + * systems with large amount of RAM. This flag is used to skip that poisoning. + * Assuming that there are no references to those newly exposed pages before + * they are ever allocated, this has little effect on KASAN memory tracking. + * All memory allocated normally after boot gets poisoned as usual. + */ +#define FPI_SKIP_KASAN_POISON ((__force fpi_t)BIT(2)) + /* prevent >1 _updater_ of zone percpu pageset ->high and ->batch fields */ static DEFINE_MUTEX(pcp_batch_high_lock); #define MIN_PERCPU_PAGELIST_FRACTION (8) @@ -384,10 +395,14 @@ static DEFINE_STATIC_KEY_TRUE(deferred_pages); * on-demand allocation and then freed again before the deferred pages * initialization is done, but this is not likely to happen. */ -static inline void kasan_free_nondeferred_pages(struct page *page, int order) +static inline void kasan_free_nondeferred_pages(struct page *page, int order, + fpi_t fpi_flags) { - if (!static_branch_unlikely(&deferred_pages)) - kasan_free_pages(page, order); + if (static_branch_unlikely(&deferred_pages)) + return; + if (fpi_flags & FPI_SKIP_KASAN_POISON) + return; + kasan_free_pages(page, order); } /* Returns true if the struct page for the pfn is uninitialised */ @@ -438,7 +453,13 @@ defer_init(int nid, unsigned long pfn, unsigned long end_pfn) return false; } #else -#define kasan_free_nondeferred_pages(p, o) kasan_free_pages(p, o) +static inline void kasan_free_nondeferred_pages(struct page *page, int order, + fpi_t fpi_flags) +{ + if (fpi_flags & FPI_SKIP_KASAN_POISON) + return; + kasan_free_pages(page, order); +} static inline bool early_page_uninitialised(unsigned long pfn) { @@ -1216,7 +1237,7 @@ static void kernel_init_free_pages(struct page *page, int numpages) } static __always_inline bool free_pages_prepare(struct page *page, - unsigned int order, bool check_free) + unsigned int order, bool check_free, fpi_t fpi_flags) { int bad = 0; @@ -1290,7 +1311,7 @@ static __always_inline bool free_pages_prepare(struct page *page, debug_pagealloc_unmap_pages(page, 1 << order); - kasan_free_nondeferred_pages(page, order); + kasan_free_nondeferred_pages(page, order, fpi_flags); return true; } @@ -1303,7 +1324,7 @@ static __always_inline bool free_pages_prepare(struct page *page, */ static bool free_pcp_prepare(struct page *page) { - return free_pages_prepare(page, 0, true); + return free_pages_prepare(page, 0, true, FPI_NONE); } static bool bulkfree_pcp_prepare(struct page *page) @@ -1323,9 +1344,9 @@ static bool bulkfree_pcp_prepare(struct page *page) static bool free_pcp_prepare(struct page *page) { if (debug_pagealloc_enabled_static()) - return free_pages_prepare(page, 0, true); + return free_pages_prepare(page, 0, true, FPI_NONE); else - return free_pages_prepare(page, 0, false); + return free_pages_prepare(page, 0, false, FPI_NONE); } static bool bulkfree_pcp_prepare(struct page *page) @@ -1533,7 +1554,7 @@ static void __free_pages_ok(struct page *page, unsigned int order, int migratetype; unsigned long pfn = page_to_pfn(page); - if (!free_pages_prepare(page, order, true)) + if (!free_pages_prepare(page, order, true, fpi_flags)) return; migratetype = get_pfnblock_migratetype(page, pfn); @@ -1570,7 +1591,7 @@ void __free_pages_core(struct page *page, unsigned int order) * Bypass PCP and place fresh pages right to the tail, primarily * relevant for memory onlining. */ - __free_pages_ok(page, order, FPI_TO_TAIL); + __free_pages_ok(page, order, FPI_TO_TAIL | FPI_SKIP_KASAN_POISON); } #ifdef CONFIG_NEED_MULTIPLE_NODES