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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 54288C25B06 for ; Thu, 4 Aug 2022 22:40:54 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 9763C8E0002; Thu, 4 Aug 2022 18:40:53 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 9251C8E0001; Thu, 4 Aug 2022 18:40:53 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 813B18E0002; Thu, 4 Aug 2022 18:40:53 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id 71CB98E0001 for ; Thu, 4 Aug 2022 18:40:53 -0400 (EDT) Received: from smtpin02.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay06.hostedemail.com (Postfix) with ESMTP id 46E10AB545 for ; Thu, 4 Aug 2022 22:40:53 +0000 (UTC) X-FDA: 79763381586.02.CDF7FE6 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by imf27.hostedemail.com (Postfix) with ESMTP id E035F4005D for ; Thu, 4 Aug 2022 22:40:52 +0000 (UTC) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id CCBFA6184D; Thu, 4 Aug 2022 22:40:51 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id EE68EC433D7; Thu, 4 Aug 2022 22:40:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1659652851; bh=HC3VLcyNerHzBCf5Q7tnpfnSFobvXPDPWfF49Lx8cz0=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=OX3gFSgcbaDGFfMXilhc5jn1RKyrYRvXBk9fvrjbTsBnN5Mb7B1RpKicgbcf12l9y j29F6tp81PnKPHHJUjRwbpccWE/+3LYgjjIKDEZfMEwKrFwCHYwsohyzClVCFS6OZg HifyYlqyvM3ckjWoalvRjxmXyaddw6S9wtbDydOQ= Date: Thu, 4 Aug 2022 15:40:50 -0700 From: Andrew Morton To: Peter Xu Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, Yang Shi , Nadav Amit , David Hildenbrand , Konstantin Khlebnikov Subject: Re: [PATCH] mm/smaps: Don't access young/dirty bit if pte unpresent Message-Id: <20220804154050.e6ab9f8c38e2445acc5b57b1@linux-foundation.org> In-Reply-To: <20220803220329.46299-1-peterx@redhat.com> References: <20220803220329.46299-1-peterx@redhat.com> X-Mailer: Sylpheed 3.7.0 (GTK+ 2.24.33; x86_64-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1659652853; a=rsa-sha256; cv=none; b=18fCrLOCFu5mvB2ie1clSqSpXgb63VLxJlRXV79EH4PwMNUHtEwAqBO5HnI0coLN4nTbR4 ZKFz41LM9nulWduaRd3fsvjqJYBQ3qpui+xgvIDEKwWdz2uyVGh8VQpb4uOzDb2LQjdOc8 G9GEdDFb9+jKrldn/XPjSdjy9/slezc= ARC-Authentication-Results: i=1; imf27.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=korg header.b=OX3gFSgc; dmarc=none; spf=pass (imf27.hostedemail.com: domain of akpm@linux-foundation.org designates 139.178.84.217 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1659652853; 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:in-reply-to:references:references:dkim-signature; bh=KK/yBjyZqQ2OihDmxB0NVwN0meZrblS0B/JH4EeE9pg=; b=RmBQk15gkTd7BAoMMu0rvFkeZ84Oc9DD8q+UvuSNHJ17hiFBn1eFuo0c1dQxeABdtZZ1O4 ERLfHhXm4BX+6pT0aJc7YTT2OA/ZAd4oPh/4X/vkdr9xigXRI8kuLKtSCeW0dYicCnY5J4 sgECF4BBxSX4SkJ9e6Na3msrDKQA8ng= X-Stat-Signature: zsdc1qcuh8je8iaiqzny5s13ntc6ta7q X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: E035F4005D Authentication-Results: imf27.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=korg header.b=OX3gFSgc; dmarc=none; spf=pass (imf27.hostedemail.com: domain of akpm@linux-foundation.org designates 139.178.84.217 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org X-Rspam-User: X-HE-Tag: 1659652852-801885 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: On Wed, 3 Aug 2022 18:03:29 -0400 Peter Xu wrote: > These bits should only be valid when the ptes are present. Introducing two > booleans for it and set it to false when !pte_present(). Please (always) describe the user visible runtime effects of the bug which is being fixed? > --- a/fs/proc/task_mmu.c > +++ b/fs/proc/task_mmu.c > @@ -527,10 +527,12 @@ static void smaps_pte_entry(pte_t *pte, unsigned long addr, > struct vm_area_struct *vma = walk->vma; > bool locked = !!(vma->vm_flags & VM_LOCKED); > struct page *page = NULL; > - bool migration = false; > + bool migration = false, young = false, dirty = false; > > if (pte_present(*pte)) { > page = vm_normal_page(vma, addr, *pte); > + young = pte_young(*pte); > + dirty = pte_dirty(*pte); > } else if (is_swap_pte(*pte)) { > swp_entry_t swpent = pte_to_swp_entry(*pte); > > @@ -560,8 +562,7 @@ static void smaps_pte_entry(pte_t *pte, unsigned long addr, > if (!page) > return; > > - smaps_account(mss, page, false, pte_young(*pte), pte_dirty(*pte), > - locked, migration); > + smaps_account(mss, page, false, young, dirty, locked, migration); > } > > #ifdef CONFIG_TRANSPARENT_HUGEPAGE > -- > 2.32.0