From patchwork Fri Dec 10 11:02:08 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Naoya Horiguchi X-Patchwork-Id: 12669299 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 C7AAFC433EF for ; Fri, 10 Dec 2021 11:03:08 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 17CEB6B0071; Fri, 10 Dec 2021 06:02:58 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 12C236B0072; Fri, 10 Dec 2021 06:02:58 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 01AAD6B0074; Fri, 10 Dec 2021 06:02:57 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0144.hostedemail.com [216.40.44.144]) by kanga.kvack.org (Postfix) with ESMTP id E34636B0071 for ; Fri, 10 Dec 2021 06:02:57 -0500 (EST) Received: from smtpin14.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id A11648249980 for ; Fri, 10 Dec 2021 11:02:47 +0000 (UTC) X-FDA: 78901596774.14.B5C0D05 Received: from out0.migadu.com (out0.migadu.com [94.23.1.103]) by imf09.hostedemail.com (Postfix) with ESMTP id 48F34140004 for ; Fri, 10 Dec 2021 11:02:44 +0000 (UTC) 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=1639134163; 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; bh=crOYlgjr6TJQi4fWo9njLpi/uZBGieqA7+/rnQHOBK8=; b=TlsQaoW0afvqpwqbG9OMB38r8CsUgGwszyRJfd2I0pZk+9qAaNVT/oiWmS0IoI3regwT1L gdSVcoPFOT1ldGVqlcettgUBRjqMQaTNq5Tp7OMsZgosc03owNZ4tsc6j1D1Bha9kZKHtP aGEns7ikvMpyTpUqlcWLMxH/Umwi1l0= From: Naoya Horiguchi To: linux-mm@kvack.org Cc: Andrew Morton , luofei@unicloud.com, Naoya Horiguchi , linux-kernel@vger.kernel.org Subject: [PATCH v1] mm, hwpoison: fix condition in free hugetlb page path Date: Fri, 10 Dec 2021 20:02:08 +0900 Message-Id: <20211210110208.879740-1-naoya.horiguchi@linux.dev> MIME-Version: 1.0 X-Migadu-Flow: FLOW_OUT X-Migadu-Auth-User: naoya.horiguchi@linux.dev X-Stat-Signature: opajwd73eg7h9unpzzwywjcfnp387y7o Authentication-Results: imf09.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=TlsQaoW0; spf=pass (imf09.hostedemail.com: domain of naoya.horiguchi@linux.dev designates 94.23.1.103 as permitted sender) smtp.mailfrom=naoya.horiguchi@linux.dev; dmarc=pass (policy=none) header.from=linux.dev X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 48F34140004 X-HE-Tag: 1639134164-735491 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 When a memory error hits a tail page of a free hugepage, __page_handle_poison() is expected to be called to isolate the error in 4kB unit, but it's not called due to the outdated if-condition in memory_failure_hugetlb(). This loses the chance to isolate the error in the finer unit, so it's not optimal. Drop the condition. This "(p != head && TestSetPageHWPoison(head)" condition is based on the old semantics of PageHWPoison on hugepage (where PG_hwpoison flag was set on the subpage), so it's not necessray any more. By getting to set PG_hwpoison on head page for hugepages, concurrent error events on different subpages in a single hugepage can be prevented by TestSetPageHWPoison(head) at the beginning of memory_failure_hugetlb(). So dropping the condition should not reopen the race window originally mentioned in commit b985194c8c0a ("hwpoison, hugetlb: lock_page/unlock_page does not match for handling a free hugepage") Reported-by: Fei Luo Signed-off-by: Naoya Horiguchi Cc: # v5.14+ Reviewed-by: Mike Kravetz --- I set v5.14+ for stable trees because the base code was greatly changed by commit 0ed950d1f281 ("mm,hwpoison: make get_hwpoison_page() call get_any_page()"), and this patch is not cleanly applicable, although the original issue was introduced more previously. --- mm/memory-failure.c | 21 +++++++-------------- 1 file changed, 7 insertions(+), 14 deletions(-) diff --git a/mm/memory-failure.c b/mm/memory-failure.c index 8f0ee5b08696..68d9a35f8908 100644 --- a/mm/memory-failure.c +++ b/mm/memory-failure.c @@ -1521,24 +1521,17 @@ static int memory_failure_hugetlb(unsigned long pfn, int flags) if (!(flags & MF_COUNT_INCREASED)) { res = get_hwpoison_page(p, flags); if (!res) { - /* - * Check "filter hit" and "race with other subpage." - */ lock_page(head); - if (PageHWPoison(head)) { - if ((hwpoison_filter(p) && TestClearPageHWPoison(p)) - || (p != head && TestSetPageHWPoison(head))) { + if (hwpoison_filter(p)) { + if (TestClearPageHWPoison(head)) num_poisoned_pages_dec(); - unlock_page(head); - return 0; - } + unlock_page(head); + return 0; } unlock_page(head); - res = MF_FAILED; - if (__page_handle_poison(p)) { - page_ref_inc(p); - res = MF_RECOVERED; - } + res = MF_RECOVERED; + if (!page_handle_poison(p, true, false)) + res = MF_FAILED; action_result(pfn, MF_MSG_FREE_HUGE, res); return res == MF_RECOVERED ? 0 : -EBUSY; } else if (res < 0) {