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Wed, 1 Jul 2026 12:05:14 +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 7SVzLXoCRWoPMwAAD6G6ig (envelope-from ); Wed, 01 Jul 2026 12:05:14 +0000 Date: Wed, 1 Jul 2026 13:05:13 +0100 From: Pedro Falcato To: Zi Yan Cc: Gregg Leventhal , Alexander Viro , Christian Brauner , Jan Kara , Matthew Wilcox , Andrew Morton , Song Liu , linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Eric Hagberg , David Hildenbrand , Lorenzo Stoakes Subject: Re: Subject: [BUG/RFC] write-open file THP cache purge can discard dirty page cache Message-ID: References: Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Action: no action X-Rspamd-Queue-Id: C2A4673A87 X-Spam-Flag: NO X-Spam-Score: -4.01 X-Spam-Level: X-Spamd-Result: default: False [-4.01 / 50.00]; BAYES_HAM(-3.00)[100.00%]; NEURAL_HAM_LONG(-1.00)[-1.000]; MID_RHS_NOT_FQDN(0.50)[]; R_DKIM_ALLOW(-0.20)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; MX_GOOD(-0.01)[]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; MIME_TRACE(0.00)[0:+]; FUZZY_RATELIMITED(0.00)[rspamd.com]; RBL_SPAMHAUS_BLOCKED_OPENRESOLVER(0.00)[2a07:de40:b281:104:10:150:64:97:from]; RCPT_COUNT_TWELVE(0.00)[14]; SPAMHAUS_XBL(0.00)[2a07:de40:b281:104:10:150:64:97:from]; ARC_NA(0.00)[]; FROM_HAS_DN(0.00)[]; TO_DN_SOME(0.00)[]; DNSWL_BLOCKED(0.00)[2a07:de40:b281:104:10:150:64:97:from,2a07:de40:b281:106:10:150:64:167:received]; RCVD_COUNT_TWO(0.00)[2]; FROM_EQ_ENVFROM(0.00)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; RECEIVED_SPAMHAUS_BLOCKED_OPENRESOLVER(0.00)[2a07:de40:b281:106:10:150:64:167:received]; MISSING_XM_UA(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; RCVD_TLS_ALL(0.00)[]; DKIM_TRACE(0.00)[suse.de:+]; DBL_BLOCKED_OPENRESOLVER(0.00)[nvidia.com:email,imap1.dmz-prg2.suse.org:rdns,imap1.dmz-prg2.suse.org:helo,suse.de:dkim] X-Rspamd-Server: rspamd1.dmz-prg2.suse.org On Tue, Jun 30, 2026 at 06:48:39PM -0400, Zi Yan wrote: > On Tue Jun 30, 2026 at 3:55 PM EDT, Pedro Falcato wrote: > > On Tue, Jun 30, 2026 at 07:49:12PM +0100, Pedro Falcato wrote: > > snip > >> > >> Other idea: perhaps doing filemap_write_and_wait() after the nr_thps > >> increment in collapse_file() will Just Work and result in a _much_ > >> simpler fix. And it avoids any weird forward-progress issues as no one can > >> write to folios at that point. > >> > > > > Gregg, if you could test this patch, it would be much appreciated. This patch > > (hopefully) makes it so no dirty folio will ever coexist with a ro-THP, thus > > hopefully sidestepping the entire issue in a simple way. Only compile-tested > > and not reviewed. > > I tested the patch on v6.12 kernel with the reproducer from Gregg and > confirmed that the issue is fixed. > > Feel free to add > Tested-by: Zi Yan Awesome, thanks! -- Pedro