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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id DF1AEC433F5 for ; Thu, 4 Nov 2021 08:19:06 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 77836610D0 for ; Thu, 4 Nov 2021 08:19:06 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 77836610D0 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linuxfoundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvack.org Received: by kanga.kvack.org (Postfix) id BAE166B006C; Thu, 4 Nov 2021 04:19:05 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id B5D806B0072; Thu, 4 Nov 2021 04:19:05 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id A73C36B0073; Thu, 4 Nov 2021 04:19:05 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0195.hostedemail.com [216.40.44.195]) by kanga.kvack.org (Postfix) with ESMTP id 96A936B006C for ; Thu, 4 Nov 2021 04:19:05 -0400 (EDT) Received: from smtpin01.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 3DC436E137 for ; Thu, 4 Nov 2021 08:19:05 +0000 (UTC) X-FDA: 78770547492.01.06FDEA7 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf19.hostedemail.com (Postfix) with ESMTP id E3758B0000B2 for ; Thu, 4 Nov 2021 08:18:57 +0000 (UTC) Received: by mail.kernel.org (Postfix) with ESMTPSA id 361346109F; Thu, 4 Nov 2021 08:19:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1636013943; bh=39bmnQD+ialegzjYuN+MfJdUlFzG0QI1Y/efWM8IaRM=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=e0xmht4BEtvIt4tkkSM/k07FA+pbFHXjyWh+DR9mhncTebVq6q7poxG7fdQpHPeCa ZJCEvFZvGnQtyvhXmSNuB9m+SHToKzWjOpCOqeL6GSj1TD+Ir/VUGmd2RDOfBn9DK1 cU3/xJIEBpJ82i5HXAcG/3+Sdp986MUJs0sO7+dA= Date: Thu, 4 Nov 2021 09:19:01 +0100 From: Greg KH To: Yang Shi Cc: hughd@google.com, sunhao.th@gmail.com, willy@infradead.org, kirill.shutemov@linux.intel.com, songliubraving@fb.com, andrea.righi@canonical.com, akpm@linux-foundation.org, stable@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [stable 5.10 PATCH] mm: khugepaged: skip huge page collapse for special files Message-ID: References: <20211103202258.3564-1-shy828301@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20211103202258.3564-1-shy828301@gmail.com> X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: E3758B0000B2 X-Stat-Signature: hn6kb1u39hmwjdgxo75terya3e9rbi99 Authentication-Results: imf19.hostedemail.com; dkim=pass header.d=linuxfoundation.org header.s=korg header.b=e0xmht4B; dmarc=pass (policy=none) header.from=linuxfoundation.org; spf=pass (imf19.hostedemail.com: domain of gregkh@linuxfoundation.org designates 198.145.29.99 as permitted sender) smtp.mailfrom=gregkh@linuxfoundation.org X-HE-Tag: 1636013937-981727 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000003, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Wed, Nov 03, 2021 at 01:22:58PM -0700, Yang Shi wrote: > commit a4aeaa06d45e90f9b279f0b09de84bd00006e733 upstream. > > The read-only THP for filesystems will collapse THP for files opened > readonly and mapped with VM_EXEC. The intended usecase is to avoid TLB > misses for large text segments. But it doesn't restrict the file types > so a THP could be collapsed for a non-regular file, for example, block > device, if it is opened readonly and mapped with EXEC permission. This > may cause bugs, like [1] and [2]. > > This is definitely not the intended usecase, so just collapse THP for > regular files in order to close the attack surface. > > [shy828301@gmail.com: fix vm_file check [3]] Now queued up, thanks. greg k-h