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Mon, 15 Jan 2024 07:49:37 +0000 (UTC) Message-ID: Date: Mon, 15 Jan 2024 12:49:45 +0500 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Cc: Muhammad Usama Anjum , akpm@linux-foundation.org, muchun.song@linux.dev, jiaqiyan@google.com, willy@infradead.org, linmiaohe@huawei.com, naoya.horiguchi@nec.com, shy828301@gmail.com, jthoughton@google.com, jane.chu@oracle.com, stable@vger.kernel.org, "kernel@collabora.com" Subject: Re: [PATCH v2] fs/hugetlbfs/inode.c: mm/memory-failure.c: fix hugetlbfs hwpoison handling Content-Language: en-US To: Sidhartha Kumar , linux-kernel@vger.kernel.org, linux-mm@kvack.org References: <20240112180840.367006-1-sidhartha.kumar@oracle.com> From: Muhammad Usama Anjum In-Reply-To: <20240112180840.367006-1-sidhartha.kumar@oracle.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 7FA9114001A X-Stat-Signature: 5tcdmiuw1c53ie1yzg37ezauzwjxxefp X-Rspam-User: X-HE-Tag: 1705304981-216710 X-HE-Meta: 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 CNkkk3KA 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 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: List-Subscribe: List-Unsubscribe: On 1/12/24 11:08 PM, 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 Tested-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)); > > if (count > 0) { > pr_err("%#lx: %s still referenced by %d users\n", -- BR, Muhammad Usama Anjum