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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id B7B67C433EF for ; Fri, 8 Jul 2022 05:38:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237307AbiGHFib (ORCPT ); Fri, 8 Jul 2022 01:38:31 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52474 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237227AbiGHFiH (ORCPT ); Fri, 8 Jul 2022 01:38:07 -0400 Received: from out2.migadu.com (out2.migadu.com [IPv6:2001:41d0:2:aacc::]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 29ADF7B349 for ; Thu, 7 Jul 2022 22:38:04 -0700 (PDT) X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1657258682; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=vOmKEsP5qHLQsoJSDPiON+o/eMH2bk607wMScNN4r/I=; b=sM2ptqqmr90GKbmlteE88gbqhMsdouCnpfczZuEQd0cSpbWUr3S6Vqwtdci2TBB40cVSWM qstknsxn//EHkKpCWkMk+BeNkNsTs4B31iyaZCfJVYoBVxsIw96s78oVZyhPOycCPLBz2A tIGf4MA0iAEtUbrJFRzU9hw3dpkzVBw= From: Naoya Horiguchi To: linux-mm@kvack.org Cc: Andrew Morton , David Hildenbrand , Mike Kravetz , Miaohe Lin , Liu Shixin , Yang Shi , Oscar Salvador , Muchun Song , Naoya Horiguchi , linux-kernel@vger.kernel.org Subject: [mm-unstable PATCH v5 7/8] mm, hwpoison: skip raw hwpoison page in freeing 1GB hugepage Date: Fri, 8 Jul 2022 14:36:52 +0900 Message-Id: <20220708053653.964464-8-naoya.horiguchi@linux.dev> In-Reply-To: <20220708053653.964464-1-naoya.horiguchi@linux.dev> References: <20220708053653.964464-1-naoya.horiguchi@linux.dev> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT X-Migadu-Auth-User: linux.dev Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Naoya Horiguchi Currently if memory_failure() (modified to remove blocking code with subsequent patch) is called on a page in some 1GB hugepage, memory error handling fails and the raw error page gets into leaked state. The impact is small in production systems (just leaked single 4kB page), but this limits the testability because unpoison doesn't work for it. We can no longer create 1GB hugepage on the 1GB physical address range with such leaked pages, that's not useful when testing on small systems. When a hwpoison page in a 1GB hugepage is handled, it's caught by the PageHWPoison check in free_pages_prepare() because the 1GB hugepage is broken down into raw error pages before coming to this point: if (unlikely(PageHWPoison(page)) && !order) { ... return false; } Then, the page is not sent to buddy and the page refcount is left 0. Originally this check is supposed to work when the error page is freed from page_handle_poison() (that is called from soft-offline), but now we are opening another path to call it, so the callers of __page_handle_poison() need to handle the case by considering the return value 0 as success. Then page refcount for hwpoison is properly incremented so unpoison works. Signed-off-by: Naoya Horiguchi Reviewed-by: Miaohe Lin --- v2 -> v3: - remove "res = MF_FAILED" in try_memory_failure_hugetlb (by Miaohe) --- mm/memory-failure.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/mm/memory-failure.c b/mm/memory-failure.c index e38a94007ffe..cdf266aaabdf 100644 --- a/mm/memory-failure.c +++ b/mm/memory-failure.c @@ -1084,7 +1084,6 @@ static int me_huge_page(struct page_state *ps, struct page *p) res = truncate_error_page(hpage, page_to_pfn(p), mapping); unlock_page(hpage); } else { - res = MF_FAILED; unlock_page(hpage); /* * migration entry prevents later access on error hugepage, @@ -1092,9 +1091,11 @@ static int me_huge_page(struct page_state *ps, struct page *p) * subpages. */ put_page(hpage); - if (__page_handle_poison(p) > 0) { + if (__page_handle_poison(p) >= 0) { page_ref_inc(p); res = MF_RECOVERED; + } else { + res = MF_FAILED; } } @@ -1860,10 +1861,11 @@ static int try_memory_failure_hugetlb(unsigned long pfn, int flags, int *hugetlb */ if (res == 0) { unlock_page(head); - res = MF_FAILED; - if (__page_handle_poison(p) > 0) { + if (__page_handle_poison(p) >= 0) { page_ref_inc(p); res = MF_RECOVERED; + } else { + res = MF_FAILED; } action_result(pfn, MF_MSG_FREE_HUGE, res); return res == MF_RECOVERED ? 0 : -EBUSY; -- 2.25.1