From patchwork Tue Jul 4 20:06:56 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Suren Baghdasaryan X-Patchwork-Id: 13301551 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 5800CEB64D9 for ; Tue, 4 Jul 2023 20:07:05 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id AE6502800B3; Tue, 4 Jul 2023 16:07:04 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id A96132800B2; Tue, 4 Jul 2023 16:07:04 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 984F62800B3; Tue, 4 Jul 2023 16:07:04 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0013.hostedemail.com [216.40.44.13]) by kanga.kvack.org (Postfix) with ESMTP id 8B0CB2800B2 for ; Tue, 4 Jul 2023 16:07:04 -0400 (EDT) Received: from smtpin05.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay10.hostedemail.com (Postfix) with ESMTP id 58DCDC0539 for ; Tue, 4 Jul 2023 20:07:04 +0000 (UTC) X-FDA: 80975013168.05.4C57D59 Received: from mail-yw1-f201.google.com (mail-yw1-f201.google.com [209.85.128.201]) by imf15.hostedemail.com (Postfix) with ESMTP id 89F7AA0012 for ; Tue, 4 Jul 2023 20:07:02 +0000 (UTC) Authentication-Results: imf15.hostedemail.com; dkim=pass header.d=google.com header.s=20221208 header.b=6VCAkwu8; dmarc=pass (policy=reject) header.from=google.com; spf=pass (imf15.hostedemail.com: domain of 35XukZAYKCJoMOL8H5AIIAF8.6IGFCHOR-GGEP46E.ILA@flex--surenb.bounces.google.com designates 209.85.128.201 as permitted sender) smtp.mailfrom=35XukZAYKCJoMOL8H5AIIAF8.6IGFCHOR-GGEP46E.ILA@flex--surenb.bounces.google.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1688501222; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding:in-reply-to: references:dkim-signature; bh=r8il2W3A+Y7dZW8xauwfpOUi9D6SLUIEJNmGFcA4NVg=; b=LxjLeced/RSIiIZhier1kqnchBPJ1JD0dDAN+9FKGGX1oumveL29F3/J3I8S0Z1oJ2BXup T7uxr/6fIgEq1kJBpWw+r+qzMKTqBdFBwZCGeB9hCA3/umlvz211vAcNRjvS323isGg8sQ x/6YPyH6ncNyoKc8GFVCWHzJWU4B4xc= ARC-Authentication-Results: i=1; imf15.hostedemail.com; dkim=pass header.d=google.com header.s=20221208 header.b=6VCAkwu8; dmarc=pass (policy=reject) header.from=google.com; spf=pass (imf15.hostedemail.com: domain of 35XukZAYKCJoMOL8H5AIIAF8.6IGFCHOR-GGEP46E.ILA@flex--surenb.bounces.google.com designates 209.85.128.201 as permitted sender) smtp.mailfrom=35XukZAYKCJoMOL8H5AIIAF8.6IGFCHOR-GGEP46E.ILA@flex--surenb.bounces.google.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1688501222; a=rsa-sha256; cv=none; b=uR+ZfT484Rd5rWghNCzV8oZslOZCJLr5qm15MgEIxz2S45TvT8Wkn4fyUmJQumZtksALLJ yDYnyKAGr8Ckgg8b9exRRY8tU0VYMELS+Sv2/B/Em2EUorNzf0P2djm4gfW5coXPlhPNmL ujh3QBfXVEJ/pHHrFyJz1/6Pqh+NX/A= Received: by mail-yw1-f201.google.com with SMTP id 00721157ae682-56ff81be091so62927667b3.0 for ; Tue, 04 Jul 2023 13:07:02 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20221208; t=1688501221; x=1691093221; h=content-transfer-encoding:cc:to:from:subject:message-id :mime-version:date:from:to:cc:subject:date:message-id:reply-to; bh=r8il2W3A+Y7dZW8xauwfpOUi9D6SLUIEJNmGFcA4NVg=; b=6VCAkwu8Vj/qi03mCMziSMUtK2HemZuvC0I/OyVXR3EqfP3G6zpDUX/yE5A84wYXHs Vprk+pCbwwr5BJIsl2f7iCstULYXel5PXQjVyFU8x4ocxvsmJu/Ijw9ucU9zSExQSPVJ GjfBPz+I4GWvxMeyFmWCK+hZnrn51I2seHLCHVjcRPGORoPK3UC0L3RotkOC9Mpu7r22 63WqExhTkViW4O6Pxql2AJSPXAmeeLluTcOHO6Kga2OWz7K11pb+2XVjOc/Ovw26usyn NFE/enwZP1tGesPvIGeRCKvuC/KSspHC43PLVf8huMbGaGy2Y2IHO2VvZnoKNaEc8d3t OWjg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1688501221; x=1691093221; h=content-transfer-encoding:cc:to:from:subject:message-id :mime-version:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=r8il2W3A+Y7dZW8xauwfpOUi9D6SLUIEJNmGFcA4NVg=; b=k9cYI2LZDXGXgPB3pOlPbPvTxOEeUlch76xUwqvklGcJJZq7hAUoNLSzolZZOAKUxS ZaC/g1AQoaF6wNxXujgQ/K6kIx5ZPaK4rMb/7YdGaVImwyCVrKMGhPFBDLgP0mmfcHhD 3vqnx4iX/vtjmeR48dbH3dyFaaRTziJY/lvGBRFr//74VRmkwOl6Q8nwmin7LDjmMczF JVv3FgZME4L/pzXjAW3v1jerObJmrC1vbuu/zbZliisy2wd7Cd4IaYNv31ZdV9xzpWpp 3LJ1AZf7CnMLr54Nq75Q2H5/ee9wzW0ad+KUDCkzzcUTIEC6b1Eje6EYOqFP2zki3NKh Nm7g== X-Gm-Message-State: ABy/qLYYm97KVigAFi1gMBcZV2bDWTwXLEvfvFvbHuUIIehNFcLrnSzB MM4chdxVnfCKuFLqdMBuBt4LtJl78+A= X-Google-Smtp-Source: APBJJlEeX9skwLcSa6ScHb3JM5//3ONAkxhpQ7w9Tg9rQrPR9RX9XqSOF0TFni9TD5TubYd6ol0QzlgFmOw= X-Received: from surenb-desktop.mtv.corp.google.com ([2620:15c:211:201:9164:ef9f:8918:e2b6]) (user=surenb job=sendgmr) by 2002:a81:4109:0:b0:56f:f77c:3c7d with SMTP id o9-20020a814109000000b0056ff77c3c7dmr103135ywa.3.1688501221474; Tue, 04 Jul 2023 13:07:01 -0700 (PDT) Date: Tue, 4 Jul 2023 13:06:56 -0700 Mime-Version: 1.0 X-Mailer: git-send-email 2.41.0.255.g8b1d071c50-goog Message-ID: <20230704200656.2526715-1-surenb@google.com> Subject: [PATCH 1/1] fork: lock VMAs of the parent process when forking From: Suren Baghdasaryan To: akpm@linux-foundation.org Cc: jirislaby@kernel.org, jacobly.alt@gmail.com, holger@applied-asynchrony.com, hdegoede@redhat.com, michel@lespinasse.org, jglisse@google.com, mhocko@suse.com, vbabka@suse.cz, hannes@cmpxchg.org, mgorman@techsingularity.net, dave@stgolabs.net, willy@infradead.org, liam.howlett@oracle.com, peterz@infradead.org, ldufour@linux.ibm.com, paulmck@kernel.org, mingo@redhat.com, will@kernel.org, luto@kernel.org, songliubraving@fb.com, peterx@redhat.com, david@redhat.com, dhowells@redhat.com, hughd@google.com, bigeasy@linutronix.de, kent.overstreet@linux.dev, punit.agrawal@bytedance.com, lstoakes@gmail.com, peterjung1337@gmail.com, rientjes@google.com, chriscli@google.com, axelrasmussen@google.com, joelaf@google.com, minchan@google.com, rppt@kernel.org, jannh@google.com, shakeelb@google.com, tatashin@google.com, edumazet@google.com, gthelen@google.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org, Suren Baghdasaryan X-Rspamd-Queue-Id: 89F7AA0012 X-Rspam-User: X-Rspamd-Server: rspam05 X-Stat-Signature: ueujqkyxhymwpcx6pnp7p486kyghz4sd X-HE-Tag: 1688501222-929834 X-HE-Meta: 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 VO5+6/CE 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 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 forking a child process, parent write-protects an anonymous page and COW-shares it with the child being forked using copy_present_pte(). Parent's TLB is flushed right before we drop the parent's mmap_lock in dup_mmap(). If we get a write-fault before that TLB flush in the parent, and we end up replacing that anonymous page in the parent process in do_wp_page() (because, COW-shared with the child), this might lead to some stale writable TLB entries targeting the wrong (old) page. Similar issue happened in the past with userfaultfd (see flush_tlb_page() call inside do_wp_page()). Lock VMAs of the parent process when forking a child, which prevents concurrent page faults during fork operation and avoids this issue. This fix can potentially regress some fork-heavy workloads. Kernel build time did not show noticeable regression on a 56-core machine while a stress test mapping 10000 VMAs and forking 5000 times in a tight loop shows ~5% regression. If such fork time regression is unacceptable, disabling CONFIG_PER_VMA_LOCK should restore its performance. Further optimizations are possible if this regression proves to be problematic. Suggested-by: David Hildenbrand Reported-by: Jiri Slaby Closes: https://lore.kernel.org/all/dbdef34c-3a07-5951-e1ae-e9c6e3cdf51b@kernel.org/ Reported-by: Holger Hoffstätte Closes: https://lore.kernel.org/all/b198d649-f4bf-b971-31d0-e8433ec2a34c@applied-asynchrony.com/ Reported-by: Jacob Young Closes: https://bugzilla.kernel.org/show_bug.cgi?id=217624 Fixes: 0bff0aaea03e ("x86/mm: try VMA lock-based page fault handling first") Signed-off-by: Suren Baghdasaryan --- kernel/fork.c | 1 + 1 file changed, 1 insertion(+) diff --git a/kernel/fork.c b/kernel/fork.c index b85814e614a5..d2e12b6d2b18 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -686,6 +686,7 @@ static __latent_entropy int dup_mmap(struct mm_struct *mm, for_each_vma(old_vmi, mpnt) { struct file *file; + vma_start_write(mpnt); if (mpnt->vm_flags & VM_DONTCOPY) { vm_stat_account(mm, mpnt->vm_flags, -vma_pages(mpnt)); continue;