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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> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 498711C000F X-Stat-Signature: ynbp4whboaebqp36k6kea53d9d8h9zbz X-Rspam-User: X-HE-Tag: 1773945090-623881 X-HE-Meta: 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 g76i5N8I GdL5J8VO/+H59NFhm0pQ81krfxJR3ojKrIGLNSJX3w21B9hAmw0ZWoc9XMyIkjn+C0VHFn1pA4GmcrrxLmUN7ZSOrI+BYA35oy7TgUzpzIKpaeCzrC3C5UaOgQLay9WTyH1I18iHc4uSSWQTJ4mLO7N8uBUP5vFLzSuzn88/Bgh/o3wcqhFsjJQa4hYzom8G3fuMzEUcVIQsl3p2Lt8fnhWHvNp1wFdSufKl7BXiiPyLP8We/ShMXgWl6+pfNeMFdYEx/ Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 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 --- 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(struct vm_area_struct *vma, int sub_batch_idx = 0; int len; + /* Optimize for the common order-0 case. */ + if (likely(nr_ptes == 1)) { + prot_commit_flush_ptes(vma, addr, ptep, oldpte, ptent, 1, + 0, PageAnonExclusive(first_page), tlb); + return; + } + while (nr_ptes) { expected_anon_exclusive = PageAnonExclusive(first_page + sub_batch_idx); len = page_anon_exclusive_sub_batch(sub_batch_idx, nr_ptes, -- 2.53.0