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bh=87iK9xe7jEqj8FLY0xzpJ9YnRE4JGcq0drEI9hyBNkg=; b=4GfYCANTWjgXmoHN3XcHAVqKhO Wm5QWX6++YtnjHBHGHTg60GjAXJv2MBHw1WsvoLZQiL4aS3HYRPL8o038Zyy//LYPN/RYVgeyVeQM X6i7qDdmf+qoG5ZqIXTdD3rlXXv2jPXqw4g075XwfVDxzP3KdNKp6mh5iKdURhV0fWZfqvoVebtTK XEdzUgPdfKi+1WkSFhz9VnapS1pwd6iQxOqpytTjH2F6h2JPQXoFKpKBlVqziSdShIbFjFi/DVJXW MivQsut8Fi7nthd99bs6L4ydH/A6Eucfaj0zSPGiVhbBOGE0y1pHBncki098sN+u6OuPqW7q7irHu BJGorXPQ==; Received: from mcgrof by bombadil.infradead.org with local (Exim 4.96 #2 (Red Hat Linux)) id 1prRRU-002Lqt-2S; Tue, 25 Apr 2023 22:47:24 +0000 Date: Tue, 25 Apr 2023 15:47:24 -0700 From: Luis Chamberlain To: Pankaj Raghav , hughd@google.com, willy@infradead.org Cc: akpm@linux-foundation.org, brauner@kernel.org, djwong@kernel.org, da.gomez@samsung.com, a.manzanares@samsung.com, dave@stgolabs.net, yosryahmed@google.com, keescook@chromium.org, hare@suse.de, kbusch@kernel.org, patches@lists.linux.dev, linux-block@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [RFC 2/8] shmem: convert to use folio_test_hwpoison() Message-ID: References: <20230421214400.2836131-1-mcgrof@kernel.org> <20230421214400.2836131-3-mcgrof@kernel.org> <20230425110025.7tq5vdr2jfom2zdh@localhost> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230425110025.7tq5vdr2jfom2zdh@localhost> X-Rspam-User: X-Rspamd-Queue-Id: 437604000F X-Rspamd-Server: rspam01 X-Stat-Signature: y868a7z8uuroc4m3essxks9exknbokdm X-HE-Tag: 1682462857-87737 X-HE-Meta: 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 XUOcIXnr WLnU5Vqzd/X8bwekEXcyz0SPSypkBQb/YBx6qL24uxpuyfmTsWr6yBK8XdOIbFq0DmiHUql1I5TNoB9NtPVJNObNGfkEHH0jlXhb1SAsf4PIbyyKaRzXmfEKAiKF5yWQ5oF83NiFKzIJOdN2V8n67KsKZk3YGXTyvvQxaow0xEPvGSYEkctEbVW/nIAgnf3/QmvI523bybOzJ1ywklVrlWueHyz3MY+gb9VLG28eQMVOM2dhWMvhGgnvEyLXhF2Vm8yGzDCDOTAO3oiGEDirAxf3RytXcU8bllbzacXfGBAX2wjMEUVwzMmaGjvBx3fQl5fAuiPT+gyaM37qQhT1wI/DS9Il3hj/K3wG1oovwd8t8e4g= 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: On Tue, Apr 25, 2023 at 01:00:25PM +0200, Pankaj Raghav wrote: > On Fri, Apr 21, 2023 at 11:42:53PM +0100, Matthew Wilcox wrote: > > On Fri, Apr 21, 2023 at 02:43:54PM -0700, Luis Chamberlain wrote: > > > The PageHWPoison() call can be converted over to the respective folio call > > > folio_test_hwpoison(). This introduces no functional changes. > > > > Um, no. Nobody should use folio_test_hwpoison(), it's a nonsense. > > > > Individual pages are hwpoisoned. You're only testing the head page > > if you use folio_test_hwpoison(). There's folio_has_hwpoisoned() to > > test if _any_ page in the folio is poisoned. But blindly converting > > PageHWPoison to folio_test_hwpoison() is wrong. > > I see a pattern in shmem.c where first the head is tested and for large > folios, any of pages in the folio is tested for poison flag. Should we > factor it out as a helper in shmem.c and use it here? > > static ssize_t shmem_file_splice_read(struct file *in, loff_t *ppos, > ... > if (folio_test_hwpoison(folio) || > (folio_test_large(folio) && > folio_test_has_hwpoisoned(folio))) { > .. Hugh's commit 72887c976a7c9e ("shmem: minor fixes to splice-read implementation") is on point about this : "Perhaps that ugliness can be improved at the mm end later" So how about we put some lipstick on this guy now (notice right above it a similar compound page check for is_page_hwpoison()): diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h index 1c68d67b832f..6a4a571dbe50 100644 --- a/include/linux/page-flags.h +++ b/include/linux/page-flags.h @@ -883,6 +883,13 @@ static inline bool is_page_hwpoison(struct page *page) return PageHuge(page) && PageHWPoison(compound_head(page)); } +static inline bool is_folio_hwpoison(struct folio *folio) +{ + if (folio_test_hwpoison(folio)) + return true; + return folio_test_large(folio) && folio_test_has_hwpoisoned(folio); +} + /* * For pages that are never mapped to userspace (and aren't PageSlab), * page_type may be used. Because it is initialised to -1, we invert the diff --git a/mm/shmem.c b/mm/shmem.c index ef7ad684f4fb..b7f47f6b75d5 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -3013,9 +3013,7 @@ static ssize_t shmem_file_splice_read(struct file *in, loff_t *ppos, if (folio) { folio_unlock(folio); - if (folio_test_hwpoison(folio) || - (folio_test_large(folio) && - folio_test_has_hwpoisoned(folio))) { + if (is_folio_hwpoison(folio)) { error = -EIO; break; }