From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 44CCA6453 for ; Tue, 22 Mar 2022 21:44:22 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0F3C2C340F4; Tue, 22 Mar 2022 21:44:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1647985462; bh=5knbsc9OlMkSq/1JDIMEwr7Iq1plkwPjCJe2HFT5o5s=; h=Date:To:From:In-Reply-To:Subject:From; b=MeK1pPSadAhOJHBjCXNBdOmV+lXNgwsEfcOI13rfFlmV9IErLT7PNfJfGbBAVpHrZ cbcxiG7B3uFjJbh0Uxn7g6odnIgKVY30iMto9aENL2BdtTrO8t+2c/pyvwk6/apStt gnte1kXO3Hf7vQjMK2HKUtlR4E2cXLaOvsipj5hk= Date: Tue, 22 Mar 2022 14:44:21 -0700 To: naoya.horiguchi@nec.com,linmiaohe@huawei.com,akpm@linux-foundation.org,patches@lists.linux.dev,linux-mm@kvack.org,mm-commits@vger.kernel.org,torvalds@linux-foundation.org,akpm@linux-foundation.org From: Andrew Morton In-Reply-To: <20220322143803.04a5e59a07e48284f196a2f9@linux-foundation.org> Subject: [patch 115/227] mm/memory-failure.c: fix race with changing page more robustly Message-Id: <20220322214422.0F3C2C340F4@smtp.kernel.org> Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: From: Miaohe Lin Subject: mm/memory-failure.c: fix race with changing page more robustly We're only intended to deal with the non-Compound page after we split thp in memory_failure. However, the page could have changed compound pages due to race window. If this happens, we could retry once to hopefully handle the page next round. Also remove unneeded orig_head. It's always equal to the hpage. So we can use hpage directly and remove this redundant one. Link: https://lkml.kernel.org/r/20220218090118.1105-5-linmiaohe@huawei.com Signed-off-by: Miaohe Lin Acked-by: Naoya Horiguchi Signed-off-by: Andrew Morton --- mm/memory-failure.c | 20 +++++++++++++++----- 1 file changed, 15 insertions(+), 5 deletions(-) --- a/mm/memory-failure.c~mm-memory-failurec-fix-race-with-changing-page-more-robustly +++ a/mm/memory-failure.c @@ -1686,7 +1686,6 @@ int memory_failure(unsigned long pfn, in { struct page *p; struct page *hpage; - struct page *orig_head; struct dev_pagemap *pgmap; int res = 0; unsigned long page_flags; @@ -1732,7 +1731,7 @@ try_again: goto unlock_mutex; } - orig_head = hpage = compound_head(p); + hpage = compound_head(p); num_poisoned_pages_inc(); /* @@ -1813,10 +1812,21 @@ try_again: lock_page(p); /* - * The page could have changed compound pages during the locking. - * If this happens just bail out. + * We're only intended to deal with the non-Compound page here. + * However, the page could have changed compound pages due to + * race window. If this happens, we could try again to hopefully + * handle the page next round. */ - if (PageCompound(p) && compound_head(p) != orig_head) { + if (PageCompound(p)) { + if (retry) { + if (TestClearPageHWPoison(p)) + num_poisoned_pages_dec(); + unlock_page(p); + put_page(p); + flags &= ~MF_COUNT_INCREASED; + retry = false; + goto try_again; + } action_result(pfn, MF_MSG_DIFFERENT_COMPOUND, MF_IGNORED); res = -EBUSY; goto unlock_page; _