From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from szxga07-in.huawei.com (szxga07-in.huawei.com [45.249.212.35]) (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 710A47E; Tue, 16 Jan 2024 02:36:12 +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 [172.19.163.44]) by szxga07-in.huawei.com (SkyGuard) with ESMTP id 4TDY4S31fxz1V47r; Tue, 16 Jan 2024 10:34:32 +0800 (CST) Received: from canpemm500002.china.huawei.com (unknown [7.192.104.244]) by mail.maildlp.com (Postfix) with ESMTPS id B17FE14011F; Tue, 16 Jan 2024 10:36:09 +0800 (CST) Received: from [10.173.135.154] (10.173.135.154) 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; Tue, 16 Jan 2024 10:36:09 +0800 Subject: Re: [PATCH v2] fs/hugetlbfs/inode.c: mm/memory-failure.c: fix hugetlbfs hwpoison handling To: Sidhartha Kumar , , CC: , , , , , , , , , References: <20240112180840.367006-1-sidhartha.kumar@oracle.com> From: Miaohe Lin Message-ID: <1e59e3c8-63d5-bba1-9c00-218c3cc8f5ff@huawei.com> Date: Tue, 16 Jan 2024 10:36:08 +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: <20240112180840.367006-1-sidhartha.kumar@oracle.com> Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit X-ClientProxiedBy: dggems706-chm.china.huawei.com (10.3.19.183) To canpemm500002.china.huawei.com (7.192.104.244) On 2024/1/13 2:08, Sidhartha Kumar wrote: > has_extra_refcount() makes the assumption that the page cache adds a ref > count of 1 and subtracts this in the extra_pins case. 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 adjust the number of references coming from the page cache by > subtracing the number of pages rather than 1. > > 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 > --- > > v1 -> v2: > move ref_count adjustment to if(extra_pins) block as that represents > ref counts from the page cache per Miaohe Lin. Thanks for your update of patch. > > 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..ef7ae73b65bd 100644 > --- a/mm/memory-failure.c > +++ b/mm/memory-failure.c > @@ -976,7 +976,7 @@ static bool has_extra_refcount(struct page_state *ps, struct page *p, > int count = page_count(p) - 1; > > if (extra_pins) > - count -= 1; > + count -= folio_nr_pages(page_folio(p)); I think this should be the right solution. @extra_pins indicates the extra page refcnt from page cache. Acked-by: Miaohe Lin Thanks. > > if (count > 0) { > pr_err("%#lx: %s still referenced by %d users\n", >