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=-8.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS 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 03D73C433F5 for ; Wed, 15 Sep 2021 11:46:14 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 64BDA6128C for ; Wed, 15 Sep 2021 11:46:13 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 64BDA6128C Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=shutemov.name Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvack.org Received: by kanga.kvack.org (Postfix) id E0CE3900002; Wed, 15 Sep 2021 07:46:12 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id DBC676B0072; Wed, 15 Sep 2021 07:46:12 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id C5D10900002; Wed, 15 Sep 2021 07:46:12 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0243.hostedemail.com [216.40.44.243]) by kanga.kvack.org (Postfix) with ESMTP id B74BD6B0071 for ; Wed, 15 Sep 2021 07:46:12 -0400 (EDT) Received: from smtpin16.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 6ED2839464 for ; Wed, 15 Sep 2021 11:46:12 +0000 (UTC) X-FDA: 78589629384.16.A02A85F Received: from mail-lj1-f176.google.com (mail-lj1-f176.google.com [209.85.208.176]) by imf28.hostedemail.com (Postfix) with ESMTP id 2B33E90000A4 for ; Wed, 15 Sep 2021 11:46:12 +0000 (UTC) Received: by mail-lj1-f176.google.com with SMTP id l18so497076lji.12 for ; Wed, 15 Sep 2021 04:46:11 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=shutemov-name.20150623.gappssmtp.com; s=20150623; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=4uYqvhZeHXv+ssAcqC18NkCUO7S23+uQI3/MrtalBV0=; b=jyiV1pAooDObXMWnm3SrBe9VySDlVMgGIdz0ZOAqYFqHTDbGSqfGlclgEpgSJnLk9Q DFka1G8+6sSoD3HNSqa0AppZDm2J1kkZRyV+Ekj0m8uHjXRySHiMBmH7WY9nhKnUr/VT 35oCwlYebNGuHog/4c3gCuRkJXVh/bIk6Tdk5zhvhNarQQSivcYCtFgJSW/Rz12DW7GL jUh7hMukNOAQHN5HvXwrMx8rRg97dA6+kwG/LTGpn5AomPepMFIPfwm6cWNOVFkW6QI6 7bHQrFQgbUXL52514a9fKrhGs8YBnPNc3rmHQ/wM43OJGLye+GKaW5qLT1AkYcVARpnv qFHw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=4uYqvhZeHXv+ssAcqC18NkCUO7S23+uQI3/MrtalBV0=; b=xrgmMv9w9XE2z5IzRcqUV5bQeCE8Hu3QeWsA7VGHZjNofjka0SVginwGmVH8EBR529 l7+aiRjuFK5VI3lz3F6m5RaNI9D9dpNEsicAy16TpliZp7wZn0wTaV+pxfVJEWniV2y2 T0esURLqio84eDMylaxrGX1ZYaBHZYc1c6+XRpTrWzNow07gC6Slv2OL45K8fg+Ynraw 0LT/Un24y1V6aKuVwr9mGPRG4EUSlbve38lBkFGD+vWm6vgVf+SJxOuHn94E3+SUU4Vv Bk+xBybb5HNBr1HbbfTV3n65P4lJbNFM4Ah0v0DGbqtxlPhGKRt+cSwO9cvHKpzS58Sg wgOg== X-Gm-Message-State: AOAM5303BkZKUNN2ib+Lpqm9tJg01FTx6JQAJ50P+0BrfK9ZZJ0oe+XY wNfwpfgdJmF4ZWJe78CZIo7uhw== X-Google-Smtp-Source: ABdhPJwCBpDqQI2MR/6gQuQDuaPc18SeGMEV9d5/MeeH65Opge+QdGLHvzx00+xc1e2k20cqP9RBww== X-Received: by 2002:a2e:a546:: with SMTP id e6mr20030432ljn.117.1631706370471; Wed, 15 Sep 2021 04:46:10 -0700 (PDT) Received: from box.localdomain ([86.57.175.117]) by smtp.gmail.com with ESMTPSA id y14sm107725lfk.237.2021.09.15.04.46.09 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 15 Sep 2021 04:46:10 -0700 (PDT) Received: by box.localdomain (Postfix, from userid 1000) id 310A7102F4D; Wed, 15 Sep 2021 14:46:13 +0300 (+03) Date: Wed, 15 Sep 2021 14:46:13 +0300 From: "Kirill A. Shutemov" To: Yang Shi Cc: naoya.horiguchi@nec.com, hughd@google.com, kirill.shutemov@linux.intel.com, willy@infradead.org, osalvador@suse.de, akpm@linux-foundation.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/4] mm: filemap: check if any subpage is hwpoisoned for PMD page fault Message-ID: <20210915114613.lo26l64iqjz2qo6a@box.shutemov.name> References: <20210914183718.4236-1-shy828301@gmail.com> <20210914183718.4236-2-shy828301@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210914183718.4236-2-shy828301@gmail.com> X-Stat-Signature: n8azkq7m66mu7j494tkmewojt8eyii3k Authentication-Results: imf28.hostedemail.com; dkim=pass header.d=shutemov-name.20150623.gappssmtp.com header.s=20150623 header.b=jyiV1pAo; dmarc=none; spf=none (imf28.hostedemail.com: domain of kirill@shutemov.name has no SPF policy when checking 209.85.208.176) smtp.mailfrom=kirill@shutemov.name X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 2B33E90000A4 X-HE-Tag: 1631706372-701467 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 Tue, Sep 14, 2021 at 11:37:15AM -0700, Yang Shi wrote: > diff --git a/mm/memory.c b/mm/memory.c > index 25fc46e87214..1765bf72ed16 100644 > --- a/mm/memory.c > +++ b/mm/memory.c > @@ -3920,8 +3920,17 @@ vm_fault_t do_set_pmd(struct vm_fault *vmf, struct page *page) > if (unlikely(!pmd_none(*vmf->pmd))) > goto out; > > - for (i = 0; i < HPAGE_PMD_NR; i++) > + for (i = 0; i < HPAGE_PMD_NR; i++) { > + /* > + * Just backoff if any subpage of a THP is corrupted otherwise > + * the corrupted page may mapped by PMD silently to escape the > + * check. This kind of THP just can be PTE mapped. Access to > + * the corrupted subpage should trigger SIGBUS as expected. > + */ > + if (PageHWPoison(page + i)) > + goto out; > flush_icache_page(vma, page + i); > + } This is somewhat costly. flush_icache_page() is empty on most archs so compiler makes the loop go away before the change. Also page->flags for most of the pages will not necessary be hot. I wounder if we should consider making PG_hwpoison to cover full compound page. On marking page hwpoison we try to split it and mark relevant base page, if split fails -- mark full compound page. As alternative we can have one more flag that indicates that the compound page contains at least one hwpoisoned base page. We should have enough space in the first tail page. -- Kirill A. Shutemov