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 X-Spam-Level: X-Spam-Status: No, score=-10.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 40B31C4338F for ; Fri, 20 Aug 2021 17:14:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1B4DA61164 for ; Fri, 20 Aug 2021 17:14:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232240AbhHTRPc (ORCPT ); Fri, 20 Aug 2021 13:15:32 -0400 Received: from ms.lwn.net ([45.79.88.28]:36302 "EHLO ms.lwn.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230052AbhHTRPb (ORCPT ); Fri, 20 Aug 2021 13:15:31 -0400 Received: from localhost (unknown [IPv6:2601:281:8300:104d::5f6]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ms.lwn.net (Postfix) with ESMTPSA id 1720A5ED5; Fri, 20 Aug 2021 17:14:53 +0000 (UTC) DKIM-Filter: OpenDKIM Filter v2.11.0 ms.lwn.net 1720A5ED5 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=lwn.net; s=20201203; t=1629479693; bh=LEEzvaGgi9neocvERnESXJLRXIyANpPsPlpoWwhgMzg=; h=From:To:Cc:Subject:In-Reply-To:References:Date:From; b=l71Ggs9Xm0sZMxMd3et6JCRyidOzNNhwyjPjeSM+65Hf5x9tfwSwTYnd7PxjDNhi3 ZvqmSDepF5opOUfHAxWh7zF7ey1FJ4lTS4BN++jmPeT1RelgWEk8S58TIIrUGfmuF5 4XVBeHrO2+Tfx8GTXvwnGNF4CH6xYZ8iil7BoeaHMu82gGG+F9MNqmaB+A1Hd4SE4c ItSI9ihWE/W+f5rjJbAj2rJKkAHbiSd2T9tyZfpiIqtSgYBBd6SDoNrjZzucxEn0fX NtQTJH7KO2phgHvr2T9EYNoaMNj0GTaYcSYJ5BNL3g75yZbbnesb1pHWYHnlH4TUSi H7zKkHpW1s+kA== From: Jonathan Corbet To: Joerg Roedel , Peilin Ye Cc: Andrew Morton , x86@kernel.org, Thomas Gleixner , Ingo Molnar , Borislav Petkov , "H. Peter Anvin" , linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, Muchun Song , Cong Wang , Peilin Ye Subject: Re: [PATCH RESEND v2] docs: x86: Remove obsolete information about x86_64 vmalloc() faulting In-Reply-To: References: <20210818220123.2623-1-yepeilin.cs@gmail.com> Date: Fri, 20 Aug 2021 11:14:52 -0600 Message-ID: <87bl5srqb7.fsf@meer.lwn.net> MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org Joerg Roedel writes: > On Wed, Aug 18, 2021 at 03:01:23PM -0700, Peilin Ye wrote: >> From: Peilin Ye >> >> x86_64 vmalloc() mappings are no longer "synchronized" among page tables >> via faulting since commit 6eb82f994026 ("x86/mm: Pre-allocate P4D/PUD >> pages for vmalloc area"), since the corresponding P4D or PUD pages are >> now preallocated at boot, by preallocate_vmalloc_pages(). Drop the >> "lazily synchronized" description for less confusion. >> >> While this file is x86_64-specific, it is worth noting that things are >> different for x86_32, where vmalloc()-related changes to `init_mm.pgd` are >> synchronized to all page tables in the system during runtime, via >> arch_sync_kernel_mappings(). Unfortunately, this synchronization is >> subject to race condition, which is further handled via faulting, see >> vmalloc_fault(). See commit 4819e15f740e ("x86/mm/32: Bring back vmalloc >> faulting on x86_32") for more details. >> >> Reviewed-by: Muchun Song >> Signed-off-by: Peilin Ye > > Reviewed-by: Joerg Roedel Applied, thanks. jon