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[2003:cb:c704:3500:b8a3:191c:eae:cc05]) by smtp.gmail.com with ESMTPSA id o16-20020a056000011000b002c703d59fa7sm9956231wrx.12.2023.03.06.05.59.09 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 06 Mar 2023 05:59:10 -0800 (PST) Message-ID: Date: Mon, 6 Mar 2023 14:59:08 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.8.0 Subject: Re: [PATCH 1/6] shmem: remove check for folio lock on writepage() To: Luis Chamberlain , hughd@google.com, akpm@linux-foundation.org, willy@infradead.org, brauner@kernel.org Cc: linux-mm@kvack.org, p.raghav@samsung.com, da.gomez@samsung.com, a.manzanares@samsung.com, dave@stgolabs.net, yosryahmed@google.com, keescook@chromium.org, patches@lists.linux.dev, linux-kernel@vger.kernel.org References: <20230302232758.888157-1-mcgrof@kernel.org> <20230302232758.888157-2-mcgrof@kernel.org> From: David Hildenbrand Organization: Red Hat In-Reply-To: <20230302232758.888157-2-mcgrof@kernel.org> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Stat-Signature: bxy91gwxi1jmwiyx8rjoz7y7gosuqw4a X-Rspam-User: X-Rspamd-Queue-Id: 76E0240018 X-Rspamd-Server: rspam06 X-HE-Tag: 1678111153-604152 X-HE-Meta: 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 /StiPn9O 9jJ8uF4gCv+CW6NYyb75T2rQnOla/c5ad+CXyt3kI4Qu3InbMKfik/48vDNoLiFfQ/KbvGZyTIN1rkADi/iVyAGEP31jSNHUE8qdSpGkob92MJ2L7dBQJcR0UrLOc7SeBZbR1VDPC8VjwY4NcfZi4CmOkMNs7c9T4goqUym9ae62VarqBiNS6a4Ea2mkbGbyyRnmEvdb60LxhC31xkOzvrvFswPKNm+2lxzVUpt14U2uOFF/7/g+fzfyP74mybVWMrGSIig85MECfnLXo8dcSH+wrb5W9imfkoLqxy6916KtHblp+OJYQQitd98rxzWWefwbTfSKZvXpo/1hpdTuQogMnOztmagPRzJF6yK2Zl0r2R7DPclHKAH/jIdLqnA6Ig0pxnaDNnw5z1o9TN9sxgeyGWHPAW4uy4/RAAjcKk6oBxsZCjGl/0Ag1IoJUaBk8zIgE 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 03.03.23 00:27, Luis Chamberlain wrote: > Matthew notes we should not need to check the folio lock > on the writepage() callback so remove it. This sanity check > has been lingering since linux-history days. We remove this > as we tidy up the writepage() callback to make things a bit > clearer. > > Suggested-by: Matthew Wilcox > Signed-off-by: Luis Chamberlain > --- > mm/shmem.c | 1 - > 1 file changed, 1 deletion(-) > > diff --git a/mm/shmem.c b/mm/shmem.c > index 1af85259b6fc..7fff1a3af092 100644 > --- a/mm/shmem.c > +++ b/mm/shmem.c > @@ -1354,7 +1354,6 @@ static int shmem_writepage(struct page *page, struct writeback_control *wbc) > folio_clear_dirty(folio); > } > > - BUG_ON(!folio_test_locked(folio)); > mapping = folio->mapping; > index = folio->index; > inode = mapping->host; It's still required IIUC. At least for split_huge_page() and setting/clearing some page flags in there. At least split_huge_page() also contains a VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio); So it's probably reasonable to remove this unconditional sanity check here; removing BUG_ON's is always nice. Acked-by: David Hildenbrand -- Thanks, David / dhildenb