From mboxrd@z Thu Jan 1 00:00:00 1970 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7EB9ECCA479 for ; Mon, 18 Jul 2022 19:37:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236168AbiGRThL (ORCPT ); Mon, 18 Jul 2022 15:37:11 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57304 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236147AbiGRThG (ORCPT ); Mon, 18 Jul 2022 15:37:06 -0400 Received: from mail-pg1-x535.google.com (mail-pg1-x535.google.com [IPv6:2607:f8b0:4864:20::535]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4CB15E00D for ; Mon, 18 Jul 2022 12:37:06 -0700 (PDT) Received: by mail-pg1-x535.google.com with SMTP id bh13so11528720pgb.4 for ; Mon, 18 Jul 2022 12:37:06 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=IufP9Zf+LxI7/ja1tm+EfHoZ34yAqbNH4YNdr2fLKzg=; b=qG3NzQadQYCy4rNcC/00/m1k00Rdnq8ihunEXn9ko/dtWH2HiC/JLZcB0XE3Fmrnme 4uHW7JOvxcluNfpQxgbQVqeUgNSwGxPrf47yeAbr1vPKr2M8T3ojhSwKcIotbVOpuGpC 03vIgXyGqL1xqLnoRk6HZYGbEsfTuBQb3UTilxepLrrh6di54zWWHrvnUwafOcNixDvI mAiMqZJOgnaD3MYRYn1evGphPH12+idguFStTv1WGAkRhN95WV3+4haBwVkVtpdhUTwQ dAycGnGYVMeeHc5jfDHQcsMcyMaz2Yv5VlzLzbDlj5bMe2rXOZ12FUP7+Pdwyzf05Qjg mXxg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=IufP9Zf+LxI7/ja1tm+EfHoZ34yAqbNH4YNdr2fLKzg=; b=Sx9D+ZvR5pwK654JVRdbB36EzIVM6722qUAAoNfk59ypgWGOzSk3+7SX3Q3k0cL3JI EMWsv0L9tNN/Aoin9i/6i9r6yJlGf0tksrYW4Zmab6Ti9o+appr+4KEykGDMhOI1jzFG +/6+HEGi8upQIuLqptlAI9OmhyYLr2AvAr85M8Hy1KReptu51pguEec4//UrnPQuyu5v gNkINVzMLskN0kYUKFyU7ARypqLGk0+OgvKxD3vmLcl6Gg/nIJamOvG+MjeD9+5dMq6t FChh5OipG1Z02xJqU79dClL/E0kv1r14+QDPMqc7tFr1GD3ljByGGBwdaO0wGtEVvog8 SGeQ== X-Gm-Message-State: AJIora9kjgNshVgvCmBYjunY/YTiSw2lWLCqk4nr89qjMY549MQcs4XM I6DAKSUUDWWfYcLpLLHZ9lC1+d3pnkMDvw== X-Google-Smtp-Source: AGRyM1s4dUG7omvru0Q+c8qc7tyPUfIKb/kzYGzarbIemngP+tEUPjt2ISjbd7jZhK5SI6J3kDZqpg== X-Received: by 2002:a63:504c:0:b0:419:d02e:f42a with SMTP id q12-20020a63504c000000b00419d02ef42amr17915418pgl.566.1658173025597; Mon, 18 Jul 2022 12:37:05 -0700 (PDT) Received: from sc2-haas01-esx0118.eng.vmware.com ([66.170.99.1]) by smtp.gmail.com with ESMTPSA id q6-20020a170902a3c600b0016bc4a6ce28sm9907887plb.98.2022.07.18.12.37.04 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 18 Jul 2022 12:37:05 -0700 (PDT) From: Nadav Amit X-Google-Original-From: Nadav Amit To: linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org, Andrew Morton , Mike Rapoport , Axel Rasmussen , Nadav Amit , Andrea Arcangeli , Andrew Cooper , Andy Lutomirski , Dave Hansen , David Hildenbrand , Peter Xu , Peter Zijlstra , Thomas Gleixner , Will Deacon , Yu Zhao , Nick Piggin Subject: [RFC PATCH 02/14] userfaultfd: try to map write-unprotected pages Date: Mon, 18 Jul 2022 05:02:00 -0700 Message-Id: <20220718120212.3180-3-namit@vmware.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20220718120212.3180-1-namit@vmware.com> References: <20220718120212.3180-1-namit@vmware.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Nadav Amit When using userfaultfd write-(un)protect ioctl, try to change the PTE to be writable. This would save a page-fault afterwards. Cc: Andrea Arcangeli Cc: Andrew Cooper Cc: Andrew Morton Cc: Andy Lutomirski Cc: Dave Hansen Cc: David Hildenbrand Cc: Peter Xu Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Will Deacon Cc: Yu Zhao Cc: Nick Piggin Signed-off-by: Nadav Amit --- mm/userfaultfd.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c index e0492f5f06a0..6013b217e9f3 100644 --- a/mm/userfaultfd.c +++ b/mm/userfaultfd.c @@ -799,6 +799,8 @@ int mwriteprotect_range(struct mm_struct *dst_mm, unsigned long start, cp_flags = enable_wp ? MM_CP_UFFD_WP : MM_CP_UFFD_WP_RESOLVE; if (uffd_flags & (UFFD_FLAGS_ACCESS_LIKELY|UFFD_FLAGS_WRITE_LIKELY)) cp_flags |= MM_CP_WILL_NEED; + if (!enable_wp && (uffd_flags & UFFD_FLAGS_WRITE_LIKELY)) + cp_flags |= MM_CP_TRY_CHANGE_WRITABLE; tlb_gather_mmu(&tlb, dst_mm); change_protection(&tlb, dst_vma, start, start + len, newprot, cp_flags); -- 2.25.1