From patchwork Thu Jul 16 12:37:57 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Oscar Salvador X-Patchwork-Id: 11667315 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 123B4618 for ; Thu, 16 Jul 2020 12:38:37 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id DC5CC207CB for ; Thu, 16 Jul 2020 12:38:36 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org DC5CC207CB Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 2ACEC8D0001; Thu, 16 Jul 2020 08:38:32 -0400 (EDT) Delivered-To: linux-mm-outgoing@kvack.org Received: by kanga.kvack.org (Postfix, from userid 40) id 260608D000C; 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Thu, 16 Jul 2020 12:38:30 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id A8FF6B93D; Thu, 16 Jul 2020 12:38:33 +0000 (UTC) From: Oscar Salvador To: akpm@linux-foundation.org Cc: mhocko@suse.com, linux-mm@kvack.org, mike.kravetz@oracle.com, david@redhat.com, aneesh.kumar@linux.vnet.ibm.com, naoya.horiguchi@nec.com, linux-kernel@vger.kernel.org, Naoya Horiguchi , Oscar Salvador Subject: [PATCH v4 03/15] mm,madvise: call soft_offline_page() without MF_COUNT_INCREASED Date: Thu, 16 Jul 2020 14:37:57 +0200 Message-Id: <20200716123810.25292-4-osalvador@suse.de> X-Mailer: git-send-email 2.13.7 In-Reply-To: <20200716123810.25292-1-osalvador@suse.de> References: <20200716123810.25292-1-osalvador@suse.de> X-Rspamd-Queue-Id: 6DE0628A4ED X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam05 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: From: Naoya Horiguchi The call to get_user_pages_fast is only to get the pointer to a struct page of a given address, pinning it is memory-poisoning handler's job, so drop the refcount grabbed by get_user_pages_fast Signed-off-by: Naoya Horiguchi Signed-off-by: Oscar Salvador Reviewed-by: Mike Kravetz --- mm/madvise.c | 24 ++++++++++++------------ 1 file changed, 12 insertions(+), 12 deletions(-) diff --git a/mm/madvise.c b/mm/madvise.c index a16dba21cdf6..1fe89a5b8d33 100644 --- a/mm/madvise.c +++ b/mm/madvise.c @@ -910,16 +910,24 @@ static int madvise_inject_error(int behavior, */ size = page_size(compound_head(page)); - if (PageHWPoison(page)) { - put_page(page); + /* + * The get_user_pages_fast() is just to get the pfn of the + * given address, and the refcount has nothing to do with + * what we try to test, so it should be released immediately. + * This is racy but it's intended because the real hardware + * errors could happen at any moment and memory error handlers + * must properly handle the race. + */ + put_page(page); + + if (PageHWPoison(page)) continue; - } if (behavior == MADV_SOFT_OFFLINE) { pr_info("Soft offlining pfn %#lx at process virtual address %#lx\n", pfn, start); - ret = soft_offline_page(pfn, MF_COUNT_INCREASED); + ret = soft_offline_page(pfn, 0); if (ret) return ret; continue; @@ -927,14 +935,6 @@ static int madvise_inject_error(int behavior, pr_info("Injecting memory failure for pfn %#lx at process virtual address %#lx\n", pfn, start); - - /* - * Drop the page reference taken by get_user_pages_fast(). In - * the absence of MF_COUNT_INCREASED the memory_failure() - * routine is responsible for pinning the page to prevent it - * from being released back to the page allocator. - */ - put_page(page); ret = memory_failure(pfn, 0); if (ret) return ret;