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Wed, 25 Jun 2025 08:15:23 +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 u4CpJxuwW2iOGQAAD6G6ig (envelope-from ); Wed, 25 Jun 2025 08:15:23 +0000 Date: Wed, 25 Jun 2025 10:15:22 +0200 From: Oscar Salvador To: David Hildenbrand Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, nvdimm@lists.linux.dev, Andrew Morton , Juergen Gross , Stefano Stabellini , Oleksandr Tyshchenko , Dan Williams , Alistair Popple , Matthew Wilcox , Jan Kara , Alexander Viro , Christian Brauner , Zi Yan , Baolin Wang , Lorenzo Stoakes , "Liam R. Howlett" , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Jann Horn , Pedro Falcato Subject: Re: [PATCH RFC 06/14] mm/huge_memory: support huge zero folio in vmf_insert_folio_pmd() Message-ID: References: <20250617154345.2494405-1-david@redhat.com> <20250617154345.2494405-7-david@redhat.com> Precedence: bulk X-Mailing-List: nvdimm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250617154345.2494405-7-david@redhat.com> X-Rspamd-Server: rspamd2.dmz-prg2.suse.org X-Rspamd-Queue-Id: 2B4CD1F441 X-Rspamd-Action: no action X-Spam-Flag: NO X-Spamd-Result: default: False [-4.51 / 50.00]; BAYES_HAM(-3.00)[100.00%]; NEURAL_HAM_LONG(-1.00)[-1.000]; 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)[]; FROM_HAS_DN(0.00)[]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; FUZZY_BLOCKED(0.00)[rspamd.com]; RBL_SPAMHAUS_BLOCKED_OPENRESOLVER(0.00)[2a07:de40:b281:104:10:150:64:97:from]; SPAMHAUS_XBL(0.00)[2a07:de40:b281:104:10:150:64:97:from]; ARC_NA(0.00)[]; RCPT_COUNT_TWELVE(0.00)[29]; MIME_TRACE(0.00)[0:+]; TO_MATCH_ENVRCPT_ALL(0.00)[]; RCVD_TLS_ALL(0.00)[]; DKIM_TRACE(0.00)[suse.de:+]; DNSWL_BLOCKED(0.00)[2a07:de40:b281:106:10:150:64:167:received,2a07:de40:b281:104:10:150:64:97:from]; RCVD_COUNT_TWO(0.00)[2]; FROM_EQ_ENVFROM(0.00)[]; TO_DN_SOME(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)[]; R_RATELIMIT(0.00)[to_ip_from(RL88oxspsx4bg3gu1yybyqiqt4)]; DBL_BLOCKED_OPENRESOLVER(0.00)[localhost.localdomain:mid,imap1.dmz-prg2.suse.org:rdns,imap1.dmz-prg2.suse.org:helo,suse.de:dkim] X-Spam-Score: -4.51 X-Spam-Level: On Tue, Jun 17, 2025 at 05:43:37PM +0200, David Hildenbrand wrote: > Just like we do for vmf_insert_page_mkwrite() -> ... -> > insert_page_into_pte_locked(), support the huge zero folio. > > Signed-off-by: David Hildenbrand insert_page_into_pte_locked() creates a special pte in case it finds the zero folio while insert_pmd() doesn't. I know that we didn't want to create special mappings for normal refcount folios but this seems inconsistent? I'm pretty sure there's a reason but could you elaborate on that? > --- > mm/huge_memory.c | 8 +++++--- > 1 file changed, 5 insertions(+), 3 deletions(-) > > diff --git a/mm/huge_memory.c b/mm/huge_memory.c > index 1ea23900b5adb..92400f3baa9ff 100644 > --- a/mm/huge_memory.c > +++ b/mm/huge_memory.c > @@ -1418,9 +1418,11 @@ static vm_fault_t insert_pmd(struct vm_area_struct *vma, unsigned long addr, > if (fop.is_folio) { > entry = folio_mk_pmd(fop.folio, vma->vm_page_prot); > > - folio_get(fop.folio); > - folio_add_file_rmap_pmd(fop.folio, &fop.folio->page, vma); > - add_mm_counter(mm, mm_counter_file(fop.folio), HPAGE_PMD_NR); > + if (!is_huge_zero_folio(fop.folio)) { > + folio_get(fop.folio); > + folio_add_file_rmap_pmd(fop.folio, &fop.folio->page, vma); > + add_mm_counter(mm, mm_counter_file(fop.folio), HPAGE_PMD_NR); > + } > } else { > entry = pmd_mkhuge(pfn_pmd(fop.pfn, prot)); > entry = pmd_mkspecial(entry); > -- > 2.49.0 > > -- Oscar Salvador SUSE Labs