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Thu, 19 Mar 2026 18:31:25 +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 2PsGOf1AvGmbdgAAD6G6ig (envelope-from ); Thu, 19 Mar 2026 18:31:25 +0000 From: Pedro Falcato To: Andrew Morton , "Liam R. Howlett" , Lorenzo Stoakes Cc: Pedro Falcato , Vlastimil Babka , Jann Horn , David Hildenbrand , Dev Jain , Luke Yang , jhladky@redhat.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH 4/4] mm/mprotect: special-case small folios when applying write permissions Date: Thu, 19 Mar 2026 18:31:08 +0000 Message-ID: <20260319183108.1105090-5-pfalcato@suse.de> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260319183108.1105090-1-pfalcato@suse.de> References: <20260319183108.1105090-1-pfalcato@suse.de> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Spam-Score: -6.80 X-Spam-Level: X-Spamd-Result: default: False [-6.80 / 50.00]; REPLY(-4.00)[]; BAYES_HAM(-3.00)[100.00%]; MID_CONTAINS_FROM(1.00)[]; NEURAL_HAM_LONG(-1.00)[-1.000]; R_MISSING_CHARSET(0.50)[]; NEURAL_HAM_SHORT(-0.20)[-0.996]; MIME_GOOD(-0.10)[text/plain]; FUZZY_RATELIMITED(0.00)[rspamd.com]; ARC_NA(0.00)[]; MIME_TRACE(0.00)[0:+]; RCPT_COUNT_TWELVE(0.00)[12]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; TO_MATCH_ENVRCPT_ALL(0.00)[]; FROM_HAS_DN(0.00)[]; FROM_EQ_ENVFROM(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; RCVD_COUNT_TWO(0.00)[2]; R_RATELIMIT(0.00)[to_ip_from(RL8d8xedm6iu8o66torxsk6bwd)]; TO_DN_SOME(0.00)[]; RCVD_TLS_ALL(0.00)[]; DBL_BLOCKED_OPENRESOLVER(0.00)[suse.de:mid,suse.de:email,imap1.dmz-prg2.suse.org:helo] X-Spam-Flag: NO Content-Type: text/plain; charset="utf-8" The common order-0 case is important enough to want its own branch, and avoids the hairy, large loop logic that the CPU does not seem to handle particularly well. Signed-off-by: Pedro Falcato Reviewed-by: Lorenzo Stoakes (Oracle) --- mm/mprotect.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/mm/mprotect.c b/mm/mprotect.c index aa845f5bf14d..23a741f9a4c8 100644 --- a/mm/mprotect.c +++ b/mm/mprotect.c @@ -170,6 +170,13 @@ static __always_inline void commit_anon_folio_batch(st= ruct vm_area_struct *vma, int sub_batch_idx =3D 0; int len; =20 + /* Optimize for the common order-0 case. */ + if (likely(nr_ptes =3D=3D 1)) { + prot_commit_flush_ptes(vma, addr, ptep, oldpte, ptent, 1, + 0, PageAnonExclusive(first_page), tlb); + return; + } + while (nr_ptes) { expected_anon_exclusive =3D PageAnonExclusive(first_page + sub_batch_idx= ); len =3D page_anon_exclusive_sub_batch(sub_batch_idx, nr_ptes, --=20 2.53.0