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mm: convert FPB_IGNORE_* into FPB_RESPECT_*

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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>
This commit is contained in:
David Hildenbrand
2025-07-02 12:49:23 +02:00
committed by Andrew Morton
parent 7765794810
commit e66d7a4f55
7 changed files with 18 additions and 25 deletions
Download Patch File Download Diff File Expand all files Collapse all files

16
mm/internal.h
View File

@@ -202,17 +202,17 @@ static inline void vma_close(struct vm_area_struct *vma)
/* Flags for folio_pte_batch(). */
typedef int __bitwise fpb_t;
/* Compare PTEs after pte_mkclean(), ignoring the dirty bit. */
#define FPB_IGNORE_DIRTY ((__force fpb_t)BIT(0))
/* Compare PTEs respecting the dirty bit. */
#define FPB_RESPECT_DIRTY ((__force fpb_t)BIT(0))
/* Compare PTEs after pte_clear_soft_dirty(), ignoring the soft-dirty bit. */
#define FPB_IGNORE_SOFT_DIRTY ((__force fpb_t)BIT(1))
/* Compare PTEs respecting the soft-dirty bit. */
#define FPB_RESPECT_SOFT_DIRTY ((__force fpb_t)BIT(1))
static inline pte_t __pte_batch_clear_ignored(pte_t pte, fpb_t flags)
{
if (flags & FPB_IGNORE_DIRTY)
if (!(flags & FPB_RESPECT_DIRTY))
pte = pte_mkclean(pte);
if (likely(flags & FPB_IGNORE_SOFT_DIRTY))
if (likely(!(flags & FPB_RESPECT_SOFT_DIRTY)))
pte = pte_clear_soft_dirty(pte);
return pte_wrprotect(pte_mkold(pte));
}
@@ -236,8 +236,8 @@ static inline pte_t __pte_batch_clear_ignored(pte_t pte, fpb_t flags)
* pages of the same large folio.
*
* All PTEs inside a PTE batch have the same PTE bits set, excluding the PFN,
* the accessed bit, writable bit, dirty bit (with FPB_IGNORE_DIRTY) and
* soft-dirty bit (with FPB_IGNORE_SOFT_DIRTY).
* the accessed bit, writable bit, dirty bit (unless FPB_RESPECT_DIRTY is set)
* and soft-dirty bit (unless FPB_RESPECT_SOFT_DIRTY is set).
*
* start_ptep must map any page of the folio. max_nr must be at least one and
* must be limited by the caller so scanning cannot exceed a single page table.

3
mm/madvise.c
View File

@@ -346,10 +346,9 @@ static inline int madvise_folio_pte_batch(unsigned long addr, unsigned long end,
pte_t pte, bool *any_young,
bool *any_dirty)
{
const fpb_t fpb_flags = FPB_IGNORE_DIRTY | FPB_IGNORE_SOFT_DIRTY;
int max_nr = (end - addr) / PAGE_SIZE;
return folio_pte_batch(folio, addr, ptep, pte, max_nr, fpb_flags, NULL,
return folio_pte_batch(folio, addr, ptep, pte, max_nr, 0, NULL,
any_young, any_dirty);
}

11
mm/memory.c
View File

@@ -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,

4
mm/mempolicy.c
View File

@@ -675,7 +675,6 @@ static void queue_folios_pmd(pmd_t *pmd, struct mm_walk *walk)
static int queue_folios_pte_range(pmd_t *pmd, unsigned long addr,
unsigned long end, struct mm_walk *walk)
{
const fpb_t fpb_flags = FPB_IGNORE_DIRTY | FPB_IGNORE_SOFT_DIRTY;
struct vm_area_struct *vma = walk->vma;
struct folio *folio;
struct queue_pages *qp = walk->private;
@@ -713,8 +712,7 @@ static int queue_folios_pte_range(pmd_t *pmd, unsigned long addr,
continue;
if (folio_test_large(folio) && max_nr != 1)
nr = folio_pte_batch(folio, addr, pte, ptent,
max_nr, fpb_flags,
NULL, NULL, NULL);
max_nr, 0, NULL, NULL, NULL);
/*
* vm_normal_folio() filters out zero pages, but there might
* still be reserved folios to skip, perhaps in a VDSO.

3
mm/mlock.c
View File

@@ -307,14 +307,13 @@ void munlock_folio(struct folio *folio)
static inline unsigned int folio_mlock_step(struct folio *folio,
pte_t *pte, unsigned long addr, unsigned long end)
{
const fpb_t fpb_flags = FPB_IGNORE_DIRTY | FPB_IGNORE_SOFT_DIRTY;
unsigned int count = (end - addr) >> PAGE_SHIFT;
pte_t ptent = ptep_get(pte);
if (!folio_test_large(folio))
return 1;
return folio_pte_batch(folio, addr, pte, ptent, count, fpb_flags, NULL,
return folio_pte_batch(folio, addr, pte, ptent, count, 0, NULL,
NULL, NULL);
}

3
mm/mremap.c
View File

@@ -173,7 +173,6 @@ static pte_t move_soft_dirty_pte(pte_t pte)
static int mremap_folio_pte_batch(struct vm_area_struct *vma, unsigned long addr,
pte_t *ptep, pte_t pte, int max_nr)
{
const fpb_t flags = FPB_IGNORE_DIRTY | FPB_IGNORE_SOFT_DIRTY;
struct folio *folio;
if (max_nr == 1)
@@ -183,7 +182,7 @@ static int mremap_folio_pte_batch(struct vm_area_struct *vma, unsigned long addr
if (!folio || !folio_test_large(folio))
return 1;
return folio_pte_batch(folio, addr, ptep, pte, max_nr, flags, NULL,
return folio_pte_batch(folio, addr, ptep, pte, max_nr, 0, NULL,
NULL, NULL);
}

3
mm/rmap.c
View File

@@ -1849,7 +1849,6 @@ static inline unsigned int folio_unmap_pte_batch(struct folio *folio,
struct page_vma_mapped_walk *pvmw,
enum ttu_flags flags, pte_t pte)
{
const fpb_t fpb_flags = FPB_IGNORE_DIRTY | FPB_IGNORE_SOFT_DIRTY;
unsigned long end_addr, addr = pvmw->address;
struct vm_area_struct *vma = pvmw->vma;
unsigned int max_nr;
@@ -1869,7 +1868,7 @@ static inline unsigned int folio_unmap_pte_batch(struct folio *folio,
if (pte_unused(pte))
return 1;
return folio_pte_batch(folio, addr, pvmw->pte, pte, max_nr, fpb_flags,
return folio_pte_batch(folio, addr, pvmw->pte, pte, max_nr, 0,
NULL, NULL, NULL);
}