From patchwork Tue Dec 14 16:20:25 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexander Potapenko X-Patchwork-Id: 12676365 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 3625AC433F5 for ; Tue, 14 Dec 2021 16:32:11 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id A06706B0093; Tue, 14 Dec 2021 11:22:56 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 9DB986B0095; Tue, 14 Dec 2021 11:22:56 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 8CA1F6B0096; Tue, 14 Dec 2021 11:22:56 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0002.hostedemail.com [216.40.44.2]) by kanga.kvack.org (Postfix) with ESMTP id 7D62E6B0093 for ; Tue, 14 Dec 2021 11:22:56 -0500 (EST) Received: from smtpin20.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 4CFDA8908A for ; Tue, 14 Dec 2021 16:22:46 +0000 (UTC) X-FDA: 78916918332.20.4F37309 Received: from mail-wm1-f74.google.com (mail-wm1-f74.google.com [209.85.128.74]) by imf13.hostedemail.com (Postfix) with ESMTP id E2BBA20012 for ; Tue, 14 Dec 2021 16:22:40 +0000 (UTC) Received: by mail-wm1-f74.google.com with SMTP id 201-20020a1c04d2000000b003335bf8075fso11526558wme.0 for ; Tue, 14 Dec 2021 08:22:43 -0800 (PST) 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=e8wDcDLgqLYcyyBsUvkh60ghxris53AouQaXxm5r3VY=; b=bwbWTEarveUVX+itJ0fuWYEkY+Ic1ruhFCrxUeHNnxH5C8YooQA7cUsnyl8QWo37I6 qTSM1De/qqc5mhyJtWkyChUpcc1nvO5H+mOj9FiHjcds3GvwduBveBltJ+MOJP/LyV7c K/DQVpI3lfpjDdqbPpWHBynUKrxIhmcfVj1tonRgeT8hXBQQWaaChDGRY91NmnLmrBd8 qK7LRFOohNDU/Dbk3RB2WOgoN4+ftz4obf+oEFc+u9s1lPaqCHjHqdN5zv3+L7i8La57 4WiPTF5fv5H95tgHlFg9ybWEeaQttWWACxX/wPbwtcvTtH5Nq8FL5fccCq06rND3IElh TzAQ== 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=e8wDcDLgqLYcyyBsUvkh60ghxris53AouQaXxm5r3VY=; b=taEjIxfjur12ZqiFq0+Blgfinm5mXMCoc3JlqMWVArVk24zhE/AJ8vyWtMqcJjqZse E7ukqzyg4zn62WwQK3eEMS3oMDZckKQawHOEf2xJQbNvNA/A03KdLKro2Gi+urV8523D IQP0Uv5er3OZp89PKIpA+jyLrQtJdR3QKXZWJnYLf2BWmNAoOSEERWcB5QdEhHIpxMdZ SLWHpXJRrgMZX4LWWyQ9YqZQ8pN/QE9d8qbJcZVNTgDkxyOL94CP1/i1CGfSNc5kv2FV /yNx1A3/CTzaFIe8gzlOKRYQMKxyWonr02DoIaydhusBAQCOx4u5QN7zTFDT6NyZFZ5S o/Ig== X-Gm-Message-State: AOAM531hBLM+VKLuQcNfnX6XwoLMdBelvsPDx+5JWg+TiDsnBuQP1uFq rBB6zlbSNiBp3nPxzTdaMddUPdeVA3M= X-Google-Smtp-Source: ABdhPJzoy7nwddl4O5eQjXMqW0hLllhbb9+Sf9gHpEsPLwPy4hBpBZLzkiU1SPitQ3yLHKKXprNAepEWH4s= X-Received: from glider.muc.corp.google.com ([2a00:79e0:15:13:357e:2b9d:5b13:a652]) (user=glider job=sendgmr) by 2002:a5d:4646:: with SMTP id j6mr1679288wrs.485.1639498962614; Tue, 14 Dec 2021 08:22:42 -0800 (PST) Date: Tue, 14 Dec 2021 17:20:25 +0100 In-Reply-To: <20211214162050.660953-1-glider@google.com> Message-Id: <20211214162050.660953-19-glider@google.com> Mime-Version: 1.0 References: <20211214162050.660953-1-glider@google.com> X-Mailer: git-send-email 2.34.1.173.g76aa8bc2d0-goog Subject: [PATCH 18/43] kmsan: unpoison @tlb in arch_tlb_gather_mmu() From: Alexander Potapenko To: glider@google.com Cc: Alexander Viro , Andrew Morton , Andrey Konovalov , Andy Lutomirski , Ard Biesheuvel , Arnd Bergmann , Borislav Petkov , Christoph Hellwig , Christoph Lameter , David Rientjes , Dmitry Vyukov , Eric Dumazet , Greg Kroah-Hartman , Herbert Xu , Ilya Leoshkevich , Ingo Molnar , Jens Axboe , Joonsoo Kim , Kees Cook , Marco Elver , Matthew Wilcox , "Michael S. Tsirkin" , Pekka Enberg , Peter Zijlstra , Petr Mladek , Steven Rostedt , Thomas Gleixner , Vasily Gorbik , Vegard Nossum , Vlastimil Babka , linux-mm@kvack.org, linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: E2BBA20012 X-Stat-Signature: prdyh6oud7ow18kf35a41jrt9bzg8anz Authentication-Results: imf13.hostedemail.com; dkim=pass header.d=google.com header.s=20210112 header.b=bwbWTEar; spf=pass (imf13.hostedemail.com: domain of 30sS4YQYKCFM163yzC19916z.x97638FI-775Gvx5.9C1@flex--glider.bounces.google.com designates 209.85.128.74 as permitted sender) smtp.mailfrom=30sS4YQYKCFM163yzC19916z.x97638FI-775Gvx5.9C1@flex--glider.bounces.google.com; dmarc=pass (policy=reject) header.from=google.com X-HE-Tag: 1639498960-874997 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: This is a hack to reduce stackdepot pressure. struct mmu_gather contains 7 1-bit fields packed into a 32-bit unsigned int value. The remaining 25 bits remain uninitialized and are never used, but KMSAN updates the origin for them in zap_pXX_range() in mm/memory.c, thus creating very long origin chains. This is technically correct, but consumes too much memory. Unpoisoning the whole structure will prevent creating such chains. Signed-off-by: Alexander Potapenko --- Link: https://linux-review.googlesource.com/id/I76abee411b8323acfdbc29bc3a60dca8cff2de77 --- mm/mmu_gather.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/mm/mmu_gather.c b/mm/mmu_gather.c index 1b9837419bf9c..72e4c4ca01d27 100644 --- a/mm/mmu_gather.c +++ b/mm/mmu_gather.c @@ -1,6 +1,7 @@ #include #include #include +#include #include #include #include @@ -252,6 +253,15 @@ void tlb_flush_mmu(struct mmu_gather *tlb) static void __tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm, bool fullmm) { + /* + * struct mmu_gather contains 7 1-bit fields packed into a 32-bit + * unsigned int value. The remaining 25 bits remain uninitialized + * and are never used, but KMSAN updates the origin for them in + * zap_pXX_range() in mm/memory.c, thus creating very long origin + * chains. This is technically correct, but consumes too much memory. + * Unpoisoning the whole structure will prevent creating such chains. + */ + kmsan_unpoison_memory(tlb, sizeof(*tlb)); tlb->mm = mm; tlb->fullmm = fullmm;