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Fri, 1 Aug 2025 17:07:29 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id QAChBFH0jGjxTAAAD6G6ig (envelope-from ); Fri, 01 Aug 2025 17:07:29 +0000 Received: by quack3.suse.cz (Postfix, from userid 1000) id 65535A09FB; Fri, 1 Aug 2025 19:07:28 +0200 (CEST) Date: Fri, 1 Aug 2025 19:07:28 +0200 From: Jan Kara To: Joanne Koong Cc: linux-mm@kvack.org, brauner@kernel.org, willy@infradead.org, jack@suse.cz, hch@infradead.org, djwong@kernel.org, linux-fsdevel@vger.kernel.org, kernel-team@meta.com Subject: Re: [RFC PATCH v1 05/10] mm: add filemap_dirty_folio_pages() helper Message-ID: References: <20250801002131.255068-1-joannelkoong@gmail.com> <20250801002131.255068-6-joannelkoong@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250801002131.255068-6-joannelkoong@gmail.com> X-Stat-Signature: uge3r7dn581yqu6d4q811n1iqbkhc7ow X-Rspam-User: X-Rspamd-Queue-Id: B41DC4001F X-Rspamd-Server: rspam02 X-HE-Tag: 1754068050-69147 X-HE-Meta: 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 EiVP8xoL MXEfnqvA83HZYvZRh28Yb5ja3hUoF7GGIuSLy5zobz14L17ZRhOKCNEI+ln7BI+93LjEMEuDG5ftkWYI5JOLpt0ZXfKcsPEYkYPzj6OlmmWc0BSbiC/lZ+cSrIWkSbaTSLFGuk0upJQkyj4pwk8EvNXJ1mIliT2bMgXGh/7NTnpG3FcCb8EP3Y2wu2SaufXU2Z8ZIXKiNh8i5OUzC/mlat/a5RYkCpM+9O6fdV/u6Cmw2v0/sV/z4COMLY8M/6KBd+iYaZ92mgI6CWX+2rI0kdJ9rIstQgQQGxLlwugK60u5KUFtbB63Y/O4jBlBe0GPd8fTPe5oukGti0UjYir236gZBtBPHaIFuiaiohc2cFd4miQ3rU+uyHWS/7ziCvii/EExtu/6pp5WE4qaM2LOKesl3Uulvf/B8kkUC+sFj2kCxE3jIEYwfJcVpi5yqhJeaDHA1 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 Thu 31-07-25 17:21:26, Joanne Koong wrote: > Add filemap_dirty_folio_pages() which takes in the number of pages to dirty. > > Signed-off-by: Joanne Koong ... > diff --git a/mm/page-writeback.c b/mm/page-writeback.c > index b0ae10a6687d..a3805988f3ad 100644 > --- a/mm/page-writeback.c > +++ b/mm/page-writeback.c > @@ -2732,7 +2732,7 @@ void folio_account_cleaned(struct folio *folio, struct bdi_writeback *wb) > * try_to_free_buffers() to fail. > */ > void __folio_mark_dirty(struct folio *folio, struct address_space *mapping, > - int warn, long nr_pages) > + int warn, long nr_pages, bool newly_dirty) > { > unsigned long flags; > > @@ -2740,12 +2740,29 @@ void __folio_mark_dirty(struct folio *folio, struct address_space *mapping, > if (folio->mapping) { /* Race with truncate? */ > WARN_ON_ONCE(warn && !folio_test_uptodate(folio)); > folio_account_dirtied(folio, mapping, nr_pages); > - __xa_set_mark(&mapping->i_pages, folio_index(folio), > - PAGECACHE_TAG_DIRTY); > + if (newly_dirty) > + __xa_set_mark(&mapping->i_pages, folio_index(folio), > + PAGECACHE_TAG_DIRTY); > } > xa_unlock_irqrestore(&mapping->i_pages, flags); I think this is a dangerous coding pattern. What is making sure that by the time you get here newly_dirty is still valid? I mean the dirtying can race e.g. with writeback and so it can happen that the page is clean by the time we get here but newly_dirty is false. We are often protected by page lock when dirtying a folio but not always... So if nothing else this requires a careful documentation about correct use. Honza -- Jan Kara SUSE Labs, CR