From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f70.google.com (mail-wm0-f70.google.com [74.125.82.70]) by kanga.kvack.org (Postfix) with ESMTP id 6FB476B025E for ; Thu, 30 Nov 2017 17:15:15 -0500 (EST) Received: by mail-wm0-f70.google.com with SMTP id e70so84618wmc.6 for ; Thu, 30 Nov 2017 14:15:15 -0800 (PST) Received: from mail.linuxfoundation.org (mail.linuxfoundation.org. [140.211.169.12]) by mx.google.com with ESMTPS id r64si3674280wma.131.2017.11.30.14.15.13 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 30 Nov 2017 14:15:14 -0800 (PST) Date: Thu, 30 Nov 2017 14:15:11 -0800 From: akpm@linux-foundation.org Subject: [patch 01/15] mm: skip HWPoisoned pages when onlining pages Message-ID: <5a2082ef.O5KuTYIgAA5wXBLf%akpm@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: linux-mm@kvack.org, akpm@linux-foundation.org, ldufour@linux.vnet.ibm.com, avagin@openvz.org, bsingharora@gmail.com, glommer@openvz.org, n-horiguchi@ah.jp.nec.com, vdavydov.dev@gmail.com From: Laurent Dufour Subject: mm: skip HWPoisoned pages when onlining pages b023f46813cd ("memory-hotplug: skip HWPoisoned page when offlining pages") skipped the HWPoisoned pages when offlining pages, but this should be skipped when onlining the pages too. n-horiguchi@ah.jp.nec.com said: : If I read correctly, to "skip HWPoiosned page" in commit b023f46813cd : means that we skip the page status check for hwpoisoned pages *not* to : prevent memory offlining for memblocks with hwpoisoned pages. That : means that hwpoisoned pages can be offlined. : : And another reason to clear PageReserved is that we could reuse the : hwpoisoned page after onlining back with replacing the broken DIMM. In : this usecase, we first do unpoisoning to clear PageHWPoison, but it : doesn't work if PageReserved is set. My simple testing shows the BUG : below in unpoisoning (without the ClearPageReserved): : : Unpoison: Software-unpoisoned page 0x18000 : BUG: Bad page state in process page-types pfn:18000 : page:ffffda5440600000 count:0 mapcount:0 mapping: (null) index:0x70006b599 : flags: 0x1fffc00004081a(error|uptodate|dirty|reserved|swapbacked) : raw: 001fffc00004081a 0000000000000000 000000070006b599 00000000ffffffff : raw: dead000000000100 dead000000000200 0000000000000000 0000000000000000 : page dumped because: PAGE_FLAGS_CHECK_AT_FREE flag(s) set : bad because of flags: 0x800(reserved) Link: http://lkml.kernel.org/r/1493130472-22843-3-git-send-email-ldufour@linux.vnet.ibm.com Signed-off-by: Laurent Dufour Cc: Naoya Horiguchi Cc: Andrey Vagin Cc: Glauber Costa Cc: Vladimir Davydov Cc: Balbir Singh Signed-off-by: Andrew Morton --- mm/memory_hotplug.c | 4 ++++ 1 file changed, 4 insertions(+) diff -puN mm/memory_hotplug.c~mm-skip-hwpoisoned-pages-when-onlining-pages mm/memory_hotplug.c --- a/mm/memory_hotplug.c~mm-skip-hwpoisoned-pages-when-onlining-pages +++ a/mm/memory_hotplug.c @@ -696,6 +696,10 @@ static int online_pages_range(unsigned l if (PageReserved(pfn_to_page(start_pfn))) for (i = 0; i < nr_pages; i++) { page = pfn_to_page(start_pfn + i); + if (PageHWPoison(page)) { + ClearPageReserved(page); + continue; + } (*online_page_callback)(page); onlined_pages++; } _ -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org