From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from szxga08-in.huawei.com (szxga08-in.huawei.com [45.249.212.255]) (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 BADEF10A15; Fri, 12 Jan 2024 03:02:10 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huawei.com Received: from mail.maildlp.com (unknown [172.19.88.105]) by szxga08-in.huawei.com (SkyGuard) with ESMTP id 4TB5sF3MFmz1Q7m0; Fri, 12 Jan 2024 11:01:21 +0800 (CST) Received: from canpemm500002.china.huawei.com (unknown [7.192.104.244]) by mail.maildlp.com (Postfix) with ESMTPS id 0BB5114093A; Fri, 12 Jan 2024 11:01:53 +0800 (CST) Received: from [10.174.151.185] (10.174.151.185) by canpemm500002.china.huawei.com (7.192.104.244) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.35; Fri, 12 Jan 2024 11:01:52 +0800 Subject: Re: [PATCH] fix hugetlbfs hwpoison handling To: Sidhartha Kumar CC: , , , , , , , , , , , , References: <20240111191655.295530-1-sidhartha.kumar@oracle.com> From: Miaohe Lin Message-ID: <3b1206e2-85e5-7c66-b5eb-288cc7117420@huawei.com> Date: Fri, 12 Jan 2024 11:01:35 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.6.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 In-Reply-To: <20240111191655.295530-1-sidhartha.kumar@oracle.com> Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit X-ClientProxiedBy: dggems701-chm.china.huawei.com (10.3.19.178) To canpemm500002.china.huawei.com (7.192.104.244) On 2024/1/12 3:16, Sidhartha Kumar wrote: > has_extra_refcount() makes the assumption that a ref count of 1 means > the page is not referenced by other users. Commit a08c7193e4f1 > (mm/filemap: remove hugetlb special casing in filemap.c) modifies > __filemap_add_folio() by calling folio_ref_add(folio, nr); for all cases > (including hugtetlb) where nr is the number of pages in the folio. We > should check if the page is not referenced by other users by checking > the page count against the number of pages rather than 1. Thanks for your patch. > > In hugetlbfs_read_iter(), folio_test_has_hwpoisoned() is testing the wrong > flag as, in the hugetlb case, memory-failure code calls > folio_test_set_hwpoison() to indicate poison. folio_test_hwpoison() is the > correct function to test for that flag. > > After these fixes, the hugetlb hwpoison read selftest passes all cases. > > Fixes: a08c7193e4f1 ("mm/filemap: remove hugetlb special casing in filemap.c") > Closes: https://lore.kernel.org/linux-mm/20230713001833.3778937-1-jiaqiyan@google.com/T/#m8e1469119e5b831bbd05d495f96b842e4a1c5519 > Cc: # 6.7+ > Signed-off-by: Sidhartha Kumar > Reported-by: Muhammad Usama Anjum > Tested-by: Muhammad Usama Anjum > --- > fs/hugetlbfs/inode.c | 2 +- > mm/memory-failure.c | 2 +- > 2 files changed, 2 insertions(+), 2 deletions(-) > > diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c > index 36132c9125f9..3a248e4f7e93 100644 > --- a/fs/hugetlbfs/inode.c > +++ b/fs/hugetlbfs/inode.c > @@ -340,7 +340,7 @@ static ssize_t hugetlbfs_read_iter(struct kiocb *iocb, struct iov_iter *to) > } else { > folio_unlock(folio); > > - if (!folio_test_has_hwpoisoned(folio)) > + if (!folio_test_hwpoison(folio)) > want = nr; > else { > /* > diff --git a/mm/memory-failure.c b/mm/memory-failure.c > index d8c853b35dbb..87f6bf7d8bc1 100644 > --- a/mm/memory-failure.c > +++ b/mm/memory-failure.c > @@ -973,7 +973,7 @@ struct page_state { > static bool has_extra_refcount(struct page_state *ps, struct page *p, > bool extra_pins) > { > - int count = page_count(p) - 1; > + int count = page_count(p) - folio_nr_pages(page_folio(p)); IIRC, the refcnt of 1 here means the page is held by memory-failure. So I think it shouldn't be changed to folio_nr_pages(page_folio(p)). > > if (extra_pins) > count -= 1; Indeed @extra_pins indicates whether hugetlb page is kept in page cache. So the page refcnt of 'folio_nr_pages(page_folio(p))' might be used here. Thanks.