mm: convert FPB_IGNORE_* into FPB_RESPECT_*

Patch series "mm: folio_pte_batch() improvements", v2.

Ever since we added folio_pte_batch() for fork() + munmap() purposes, a
lot more users appeared (and more are being proposed), and more
functionality was added.

Most of the users only need basic functionality, and could benefit from a
non-inlined version.

So let's clean up folio_pte_batch() and split it into a basic
folio_pte_batch() (no flags) and a more advanced folio_pte_batch_ext(). 
Using either variant will now look much cleaner.

This series will likely conflict with some changes in some (old+new)
folio_pte_batch() users, but conflicts should be trivial to resolve.


This patch (of 4):

Respecting these PTE bits is the exception, so let's invert the meaning.

With this change, most callers don't have to pass any flags.  This is a
preparation for splitting folio_pte_batch() into a non-inlined variant
that doesn't consume any flags.

Long-term, we want folio_pte_batch() to probably ignore most common PTE
bits (e.g., write/dirty/young/soft-dirty) that are not relevant for most
page table walkers: uffd-wp and protnone might be bits to consider in the
future.  Only walkers that care about them can opt-in to respect them.

No functional change intended.

Link: https://lkml.kernel.org/r/20250702104926.212243-2-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Lance Yang <lance.yang@linux.dev>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Reviewed-by: Dev Jain <dev.jain@arm.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Byungchul Park <byungchul@sk.com>
Cc: Gregory Price <gourry@gourry.net>
Cc: "Huang, Ying" <ying.huang@linux.alibaba.com>
Cc: Jann Horn <jannh@google.com>
Cc: Joshua Hahn <joshua.hahnjy@gmail.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Mathew Brost <matthew.brost@intel.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Rakie Kim <rakie.kim@sk.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

1 files changed, 5 insertions, 6 deletions

diff --git a/mm/memory.c b/mm/memory.c
index 9944380e947d..a03f1964db33 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -990,10 +990,10 @@ copy_present_ptes(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma
 	 * by keeping the batching logic separate.
 	 */
 	if (unlikely(!*prealloc && folio_test_large(folio) && max_nr != 1)) {
-		if (src_vma->vm_flags & VM_SHARED)
-			flags |= FPB_IGNORE_DIRTY;
-		if (!vma_soft_dirty_enabled(src_vma))
-			flags |= FPB_IGNORE_SOFT_DIRTY;
+		if (!(src_vma->vm_flags & VM_SHARED))
+			flags |= FPB_RESPECT_DIRTY;
+		if (vma_soft_dirty_enabled(src_vma))
+			flags |= FPB_RESPECT_SOFT_DIRTY;
 
 		nr = folio_pte_batch(folio, addr, src_pte, pte, max_nr, flags,
 				     &any_writable, NULL, NULL);
@@ -1535,7 +1535,6 @@ static inline int zap_present_ptes(struct mmu_gather *tlb,
 		struct zap_details *details, int *rss, bool *force_flush,
 		bool *force_break, bool *any_skipped)
 {
-	const fpb_t fpb_flags = FPB_IGNORE_DIRTY | FPB_IGNORE_SOFT_DIRTY;
 	struct mm_struct *mm = tlb->mm;
 	struct folio *folio;
 	struct page *page;
@@ -1565,7 +1564,7 @@ static inline int zap_present_ptes(struct mmu_gather *tlb,
 	 * by keeping the batching logic separate.
 	 */
 	if (unlikely(folio_test_large(folio) && max_nr != 1)) {
-		nr = folio_pte_batch(folio, addr, pte, ptent, max_nr, fpb_flags,
+		nr = folio_pte_batch(folio, addr, pte, ptent, max_nr, 0,
 				     NULL, NULL, NULL);
 
 		zap_present_folio_ptes(tlb, vma, folio, page, pte, ptent, nr,