From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) (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 C50C7175B7; Mon, 15 Jan 2024 15:08:24 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="aNuSjlCh" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=h1zJVN/StgdtGJ+KvowsDPSUZpuVAQLtb4Gk0WK6sxU=; b=aNuSjlChQOa5cvpTN5zXyWQTQs P71JqXtroWZ63bfc4xkj1dF/AqNZArT6Ohf9opFouJrwod6mEL/QCECd9A9YiOByYWqgANJ51MIxB NgXvJ/qbRyEMsKUE9ANEEQ7t2ColgxlZ4X0DEfa49MW/SxKD7E+r070K/jdaiWDyfeuKfrwawA2kP iZjdPET9Nz5F9Qy5Z7jiU2Zh2n46cyC8T8UlIRO0F1ZU5nsjzRaXDfz6j4hEKg3CYr31HCVmHlAyE 0Ws04qhwYB6ZOVBBRVziJCG/yrQWDb+ULrqYDN3TbwGGi0G3UdAfNyBxsA1i3pPGVZMlR7Co49WoH 7LK+S/Tw==; Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1rPOZO-00A0HG-59; Mon, 15 Jan 2024 15:08:10 +0000 Date: Mon, 15 Jan 2024 15:08:10 +0000 From: Matthew Wilcox To: Muchun Song Cc: Sidhartha Kumar , linux-kernel@vger.kernel.org, linux-mm@kvack.org, akpm@linux-foundation.org, usama.anjum@collabora.com, jiaqiyan@google.com, linmiaohe@huawei.com, naoya.horiguchi@nec.com, shy828301@gmail.com, jthoughton@google.com, jane.chu@oracle.com, stable@vger.kernel.org Subject: Re: [PATCH v2] fs/hugetlbfs/inode.c: mm/memory-failure.c: fix hugetlbfs hwpoison handling Message-ID: References: <20240112180840.367006-1-sidhartha.kumar@oracle.com> <03168121-080f-41e4-a242-02638f5787f7@linux.dev> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <03168121-080f-41e4-a242-02638f5787f7@linux.dev> On Mon, Jan 15, 2024 at 08:02:51PM +0800, Muchun Song wrote: > On 2024/1/13 02:08, 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. > > > > 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)); > > IIUC, It seems than this also fix shmem of THP, because has_extra_refcount() > is called > from me_pagecache_clean(), right? Usually we split THPs before we get to this point, but we always poison an entire hugetlb page. This should probably change, but it's not high on my list of things to do.