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Wed, 1 Jul 2026 12:04:56 +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 ZRmcIWgCRWr6MgAAD6G6ig (envelope-from ); Wed, 01 Jul 2026 12:04:56 +0000 Date: Wed, 1 Jul 2026 13:04:54 +0100 From: Pedro Falcato To: Matthew Wilcox Cc: Gregg Leventhal , Alexander Viro , Christian Brauner , Jan Kara , Andrew Morton , Song Liu , linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Eric Hagberg , David Hildenbrand , Lorenzo Stoakes , Zi Yan Subject: Re: Subject: [BUG/RFC] write-open file THP cache purge can discard dirty page cache Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Queue-Id: 0FAF9160011 X-Stat-Signature: y9jbq8k87mitozg3hbaqczbfh9qti75z X-Rspam-User: X-Rspamd-Server: rspam03 X-HE-Tag: 1782907498-394070 X-HE-Meta: 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 KXIia6b0 j9sqLOIK6ajLsLBPg2eHuPhwRsuzRB8Q5j+LTIgJe++aCd4Ow4PrbejZhRtZQvG1hFChmk/u3BLKV6MBNJCz0EOV2oV9qpC1xg1Pgyo0xxlqKnaPFnAxodc9UwAj/Nddi19oU00ap3F6H0bhJUOzXLRcg4zK4TvKfvWhpcxk1F525eUYf3zv2Jt5Ch9TLQZwWvwIpSi6mS/uz3TSpeEe5vqaY/vy51fqiK88XBg0SsmUz4pffjE8xNOkFYAbo/3BN4jteQPlCS6Wxu+WXZU8euKwTc5gKiw/LosVISbvDWEfe/oSBMM/YdVu9Eg== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, Jul 01, 2026 at 12:54:52PM +0100, Matthew Wilcox wrote: > On Tue, Jun 30, 2026 at 08:55:12PM +0100, Pedro Falcato wrote: > > @@ -2043,6 +2044,17 @@ static int collapse_file(struct mm_struct *mm, unsigned long addr, > > */ > > try_to_unmap_flush(); > > > > + /* > > + * If collapse looks to be successful, flush any dirty pages > > + * out the page cache. With the nr_thps incremented, there won't be > > + * any new writers (nor new dirties). > > + */ > > + if (result == SCAN_SUCCEED && !is_shmem) { > > + err = filemap_write_and_wait(mapping); > > + if (err) > > + result = SCAN_WRITEBACK_FAIL; > > + } > > Oh, the other thing is that this should be conditioned on > !mapping_large_folio_support(). ACK to both of your suggestions, I'll send a proper version (once I figure out the proper way to send a stable fix that does not hit mainline). -- Pedro