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mm: make folio_pte_batch available outside of mm/memory.c 

madvise, mprotect and some others might need folio_pte_batch to check if a
range of PTEs are completely mapped to a large folio with contiguous
physical addresses.  Let's make it available in mm/internal.h.

While at it, add proper kernel doc and sanity-check more input parameters
using two additional VM_WARN_ON_FOLIO().

[21cnbao@gmail.com: build fix]
  Link: https://lkml.kernel.org/r/CAGsJ_4wWzG-37D82vqP_zt+Fcbz+URVe5oXLBc4M5wbN8A_gpQ@mail.gmail.com
[david@redhat.com: improve the doc for the exported func]
Link: https://lkml.kernel.org/r/20240227104201.337988-1-21cnbao@gmail.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Barry Song <v-songbaohua@oppo.com>
Suggested-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Ryan Roberts <ryan.roberts@arm.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Lance Yang <ioworker0@gmail.com>
Cc: Yin Fengwei <fengwei.yin@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Barry Song 2024-02-27 23:42:01 +13:00 committed by Andrew Morton
parent 9164448d31
commit ac96cc4d1c
2 changed files with 93 additions and 76 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

93
mm/internal.h
View File

@ -83,6 +83,99 @@ static inline void *folio_raw_mapping(struct folio *folio)
return (void *)(mapping & ~PAGE_MAPPING_FLAGS);
}
#ifdef CONFIG_MMU
/* 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 after pte_clear_soft_dirty(), ignoring the soft-dirty bit. */
#define FPB_IGNORE_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)
pte = pte_mkclean(pte);
if (likely(flags & FPB_IGNORE_SOFT_DIRTY))
pte = pte_clear_soft_dirty(pte);
return pte_wrprotect(pte_mkold(pte));
}
/**
* folio_pte_batch - detect a PTE batch for a large folio
* @folio: The large folio to detect a PTE batch for.
* @addr: The user virtual address the first page is mapped at.
* @start_ptep: Page table pointer for the first entry.
* @pte: Page table entry for the first page.
* @max_nr: The maximum number of table entries to consider.
* @flags: Flags to modify the PTE batch semantics.
* @any_writable: Optional pointer to indicate whether any entry except the
* first one is writable.
*
* Detect a PTE batch: consecutive (present) PTEs that map consecutive
* 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).
*
* 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.
*
* Return: the number of table entries in the batch.
*/
static inline int folio_pte_batch(struct folio *folio, unsigned long addr,
pte_t *start_ptep, pte_t pte, int max_nr, fpb_t flags,
bool *any_writable)
{
unsigned long folio_end_pfn = folio_pfn(folio) + folio_nr_pages(folio);
const pte_t *end_ptep = start_ptep + max_nr;
pte_t expected_pte, *ptep;
bool writable;
int nr;
if (any_writable)
*any_writable = false;
VM_WARN_ON_FOLIO(!pte_present(pte), folio);
VM_WARN_ON_FOLIO(!folio_test_large(folio) || max_nr < 1, folio);
VM_WARN_ON_FOLIO(page_folio(pfn_to_page(pte_pfn(pte))) != folio, folio);
nr = pte_batch_hint(start_ptep, pte);
expected_pte = __pte_batch_clear_ignored(pte_advance_pfn(pte, nr), flags);
ptep = start_ptep + nr;
while (ptep < end_ptep) {
pte = ptep_get(ptep);
if (any_writable)
writable = !!pte_write(pte);
pte = __pte_batch_clear_ignored(pte, flags);
if (!pte_same(pte, expected_pte))
break;
/*
* Stop immediately once we reached the end of the folio. In
* corner cases the next PFN might fall into a different
* folio.
*/
if (pte_pfn(pte) >= folio_end_pfn)
break;
if (any_writable)
*any_writable |= writable;
nr = pte_batch_hint(ptep, pte);
expected_pte = pte_advance_pfn(expected_pte, nr);
ptep += nr;
}
return min(ptep - start_ptep, max_nr);
}
#endif /* CONFIG_MMU */
void __acct_reclaim_writeback(pg_data_t *pgdat, struct folio *folio,
int nr_throttled);
static inline void acct_reclaim_writeback(struct folio *folio)

76
mm/memory.c
View File

@ -953,82 +953,6 @@ static __always_inline void __copy_present_ptes(struct vm_area_struct *dst_vma,
set_ptes(dst_vma->vm_mm, addr, dst_pte, pte, nr);
}
/* 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 after pte_clear_soft_dirty(), ignoring the soft-dirty bit. */
#define FPB_IGNORE_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)
pte = pte_mkclean(pte);
if (likely(flags & FPB_IGNORE_SOFT_DIRTY))
pte = pte_clear_soft_dirty(pte);
return pte_wrprotect(pte_mkold(pte));
}
/*
* Detect a PTE batch: consecutive (present) PTEs that map consecutive
* pages of the same 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).
*
* If "any_writable" is set, it will indicate if any other PTE besides the
* first (given) PTE is writable.
*/
static inline int folio_pte_batch(struct folio *folio, unsigned long addr,
pte_t *start_ptep, pte_t pte, int max_nr, fpb_t flags,
bool *any_writable)
{
unsigned long folio_end_pfn = folio_pfn(folio) + folio_nr_pages(folio);
const pte_t *end_ptep = start_ptep + max_nr;
pte_t expected_pte, *ptep;
bool writable;
int nr;
if (any_writable)
*any_writable = false;
VM_WARN_ON_FOLIO(!pte_present(pte), folio);
nr = pte_batch_hint(start_ptep, pte);
expected_pte = __pte_batch_clear_ignored(pte_advance_pfn(pte, nr), flags);
ptep = start_ptep + nr;
while (ptep < end_ptep) {
pte = ptep_get(ptep);
if (any_writable)
writable = !!pte_write(pte);
pte = __pte_batch_clear_ignored(pte, flags);
if (!pte_same(pte, expected_pte))
break;
/*
* Stop immediately once we reached the end of the folio. In
* corner cases the next PFN might fall into a different
* folio.
*/
if (pte_pfn(pte) >= folio_end_pfn)
break;
if (any_writable)
*any_writable |= writable;
nr = pte_batch_hint(ptep, pte);
expected_pte = pte_advance_pfn(expected_pte, nr);
ptep += nr;
}
return min(ptep - start_ptep, max_nr);
}
/*
* Copy one present PTE, trying to batch-process subsequent PTEs that map
* consecutive pages of the same folio by copying them as well.