From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 117C0332635 for ; Thu, 19 Mar 2026 19:06:40 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773947201; cv=none; b=MaXl39qazH83ELCyQFWfVtO7lC/CDduk2AEiNi73I8Chnmu+IH+62xQDAYoFKYkYMOhqRkKh1/ZqSaLEDEJmey80UFHOn1cJ4cBI8s3Zs1zEXAytjfFAJE/cGpgBe/2pThbdl4bJpRpv4/zzuGsoa9EekrWg8nSI03zhvZ/+prc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773947201; c=relaxed/simple; bh=TtOiXaSsXkDQakGmG0J2T+Rf2/7IPYdedxtXXKxfg4M=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=RIyfDHNitbnrjZyS2veqKFobNPnJAocEmmkhKLBW2+I1ygEgFbQsNlznLRj5fdTqXQCtMhi1c9T8H8M1nvbZDzBCzUzO0JphD8NjTk55PANSZ2+WNkvGG7hjpt9yEL3FYAu/yf7VG2UkABetmsPZav5DI95zoTXkdqm+pPKDkVo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=ZY4hq0Ne; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="ZY4hq0Ne" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1D68FC19424; Thu, 19 Mar 2026 19:06:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1773947200; bh=TtOiXaSsXkDQakGmG0J2T+Rf2/7IPYdedxtXXKxfg4M=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=ZY4hq0Ne6OXc23ydqpvNNEXtTeIP6E4w9TjijrcMgw1L0v9YfLwzqRwu7pyUVfmv9 m1+c64tC9NVeivWA4oKK1cGpiDQRWQ6od+oTW09dIO8iQol6Sx3tIrAyx+q8iJbnCF 5DfTLjXuW3tPt2QU4yg+kz5X14Npaaa7802X2igUQBysm4EOH11aW9tdjgZhXnZiDG qUf87VHWu63+6D5O6sKT8iWCpR6Dik4Y3p3JSVXLcGuJv9QRnNnxoxH//vezBYN02x 7BAsKtrzAQ0/LYizaDnoRKvwiHwbGqd8IlaGfNlAfDvgo6gfbwpEPjljaYJdAff1bM GPQE4/zBBu19g== Date: Thu, 19 Mar 2026 19:06:35 +0000 From: "Lorenzo Stoakes (Oracle)" To: Pedro Falcato Cc: Andrew Morton , "Liam R. Howlett" , Vlastimil Babka , Jann Horn , David Hildenbrand , Dev Jain , Luke Yang , jhladky@redhat.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/4] mm/mprotect: move softleaf code out of the main function Message-ID: <7217c8b1-1cc2-40c5-a513-7cede7cc1a73@lucifer.local> References: <20260319183108.1105090-1-pfalcato@suse.de> <20260319183108.1105090-3-pfalcato@suse.de> Precedence: bulk X-Mailing-List: linux-kernel@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: <20260319183108.1105090-3-pfalcato@suse.de> On Thu, Mar 19, 2026 at 06:31:06PM +0000, Pedro Falcato wrote: > Move softleaf change_pte_range code into a separate function. This makes > the change_pte_range() function (or where it inlines) a good bit > smaller. Plus it lessens cognitive load when reading through the > function. > > Signed-off-by: Pedro Falcato Honestly I like this as a refactoring, the noinline notwithstanding, so: Reviewed-by: Lorenzo Stoakes (Oracle) > --- > mm/mprotect.c | 128 +++++++++++++++++++++++++++----------------------- > 1 file changed, 68 insertions(+), 60 deletions(-) > > diff --git a/mm/mprotect.c b/mm/mprotect.c > index 1bd0d4aa07c2..8d4fa38a8a26 100644 > --- a/mm/mprotect.c > +++ b/mm/mprotect.c > @@ -211,6 +211,73 @@ 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 noinline long change_pte_softleaf(struct vm_area_struct *vma, > + unsigned long addr, pte_t *pte, pte_t oldpte, unsigned long cp_flags) > +{ > + bool uffd_wp = cp_flags & MM_CP_UFFD_WP; > + 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; This just continues in the original: if (softleaf_is_poison_marker(entry) || softleaf_is_guard_marker(entry)) continue; So this is correct. > + /* > + * 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; This incrmements pages and continues in the orignal: if (uffd_wp_resolve) { pte_clear(vma->vm_mm, addr, pte); pages++; } continue; So this is correct. > + } > + } 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; This increments pages and is at the end of the loop in the original: if (!pte_same(oldpte, newpte)) { set_pte_at(vma->vm_mm, addr, pte, newpte); pages++; } So this is correct. > + } > + 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 +384,7 @@ 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_pte_softleaf(vma, addr, pte, oldpte, cp_flags); > } > } while (pte += nr_ptes, addr += nr_ptes * PAGE_SIZE, addr != end); > lazy_mmu_mode_disable(); > -- > 2.53.0 >