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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 v3 1/2] mm/mprotect: move softleaf code out of the main function Date: Thu, 2 Apr 2026 15:16:27 +0100 Message-ID: <20260402141628.3367596-2-pfalcato@suse.de> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260402141628.3367596-1-pfalcato@suse.de> References: <20260402141628.3367596-1-pfalcato@suse.de> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Pre-Result: action=no action; module=replies; Message is reply to one we originated X-Rspamd-Pre-Result: action=no action; module=replies; Message is reply to one we originated X-Rspamd-Action: no action X-Stat-Signature: umojc6xz97xya1zpzkuk94xmhsnau5b5 X-Rspamd-Queue-Id: E22588000C X-Rspam-User: X-Rspamd-Server: rspam03 X-HE-Tag: 1775139415-939450 X-HE-Meta: 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 yEJZW9CW 7xGjbIaOAVpv6u0xnVVwtqIX69dKRymxxVeIHl5Fpbmk+5WCTzZ+V0zez2xI9Qy60qbRtSEn3kayHWXxB5hwR86RfcVoUjZlTSy8YzVGTn6P5FTJVaC/EJysJsrit95CjHfRPpE9N6Sy5wZY8XTvqKJeEU7a+RF/Xxh+XYtugrjNzh/Q= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Move softleaf change_pte_range code into a separate function. This makes the change_pte_range() function a good bit smaller, and lessens cognitive load when reading through the function. Reviewed-by: Lorenzo Stoakes (Oracle) Acked-by: David Hildenbrand (Arm) Tested-by: Luke Yang Signed-off-by: Pedro Falcato --- mm/mprotect.c | 127 ++++++++++++++++++++++++++------------------------ 1 file changed, 67 insertions(+), 60 deletions(-) diff --git a/mm/mprotect.c b/mm/mprotect.c index 9681f055b9fc..5929ce792c7b 100644 --- a/mm/mprotect.c +++ b/mm/mprotect.c @@ -211,6 +211,72 @@ static void set_write_prot_commit_flush_ptes(struct vm_area_struct *vma, commit_anon_folio_batch(vma, folio, page, addr, ptep, oldpte, ptent, nr_ptes, tlb); } +static long change_softleaf_pte(struct vm_area_struct *vma, + unsigned long addr, pte_t *pte, pte_t oldpte, unsigned long cp_flags) +{ + const bool uffd_wp = cp_flags & MM_CP_UFFD_WP; + const bool uffd_wp_resolve = cp_flags & MM_CP_UFFD_WP_RESOLVE; + softleaf_t entry = softleaf_from_pte(oldpte); + pte_t newpte; + + if (softleaf_is_migration_write(entry)) { + const struct folio *folio = softleaf_to_folio(entry); + + /* + * A protection check is difficult so + * just be safe and disable write + */ + if (folio_test_anon(folio)) + entry = make_readable_exclusive_migration_entry(swp_offset(entry)); + else + entry = make_readable_migration_entry(swp_offset(entry)); + newpte = swp_entry_to_pte(entry); + if (pte_swp_soft_dirty(oldpte)) + newpte = pte_swp_mksoft_dirty(newpte); + } else if (softleaf_is_device_private_write(entry)) { + /* + * We do not preserve soft-dirtiness. See + * copy_nonpresent_pte() for explanation. + */ + entry = make_readable_device_private_entry(swp_offset(entry)); + newpte = swp_entry_to_pte(entry); + if (pte_swp_uffd_wp(oldpte)) + newpte = pte_swp_mkuffd_wp(newpte); + } else if (softleaf_is_marker(entry)) { + /* + * Ignore error swap entries unconditionally, + * because any access should sigbus/sigsegv + * anyway. + */ + if (softleaf_is_poison_marker(entry) || + softleaf_is_guard_marker(entry)) + return 0; + /* + * If this is uffd-wp pte marker and we'd like + * to unprotect it, drop it; the next page + * fault will trigger without uffd trapping. + */ + if (uffd_wp_resolve) { + pte_clear(vma->vm_mm, addr, pte); + return 1; + } + return 0; + } else { + newpte = oldpte; + } + + if (uffd_wp) + newpte = pte_swp_mkuffd_wp(newpte); + else if (uffd_wp_resolve) + newpte = pte_swp_clear_uffd_wp(newpte); + + if (!pte_same(oldpte, newpte)) { + set_pte_at(vma->vm_mm, addr, pte, newpte); + return 1; + } + return 0; +} + static long change_pte_range(struct mmu_gather *tlb, struct vm_area_struct *vma, pmd_t *pmd, unsigned long addr, unsigned long end, pgprot_t newprot, unsigned long cp_flags) @@ -317,66 +383,7 @@ static long change_pte_range(struct mmu_gather *tlb, pages++; } } else { - softleaf_t entry = softleaf_from_pte(oldpte); - pte_t newpte; - - if (softleaf_is_migration_write(entry)) { - const struct folio *folio = softleaf_to_folio(entry); - - /* - * A protection check is difficult so - * just be safe and disable write - */ - if (folio_test_anon(folio)) - entry = make_readable_exclusive_migration_entry( - swp_offset(entry)); - else - entry = make_readable_migration_entry(swp_offset(entry)); - newpte = swp_entry_to_pte(entry); - if (pte_swp_soft_dirty(oldpte)) - newpte = pte_swp_mksoft_dirty(newpte); - } else if (softleaf_is_device_private_write(entry)) { - /* - * We do not preserve soft-dirtiness. See - * copy_nonpresent_pte() for explanation. - */ - entry = make_readable_device_private_entry( - swp_offset(entry)); - newpte = swp_entry_to_pte(entry); - if (pte_swp_uffd_wp(oldpte)) - newpte = pte_swp_mkuffd_wp(newpte); - } else if (softleaf_is_marker(entry)) { - /* - * Ignore error swap entries unconditionally, - * because any access should sigbus/sigsegv - * anyway. - */ - if (softleaf_is_poison_marker(entry) || - softleaf_is_guard_marker(entry)) - continue; - /* - * If this is uffd-wp pte marker and we'd like - * to unprotect it, drop it; the next page - * fault will trigger without uffd trapping. - */ - if (uffd_wp_resolve) { - pte_clear(vma->vm_mm, addr, pte); - pages++; - } - continue; - } else { - newpte = oldpte; - } - - if (uffd_wp) - newpte = pte_swp_mkuffd_wp(newpte); - else if (uffd_wp_resolve) - newpte = pte_swp_clear_uffd_wp(newpte); - - if (!pte_same(oldpte, newpte)) { - set_pte_at(vma->vm_mm, addr, pte, newpte); - pages++; - } + pages += change_softleaf_pte(vma, addr, pte, oldpte, cp_flags); } } while (pte += nr_ptes, addr += nr_ptes * PAGE_SIZE, addr != end); lazy_mmu_mode_disable(); -- 2.53.0