On Tue, Feb 27, 2024 at 11:22 PM Lance Yang <ioworker0@xxxxxxxxx> wrote: > > On Tue, Feb 27, 2024 at 5:14 PM David Hildenbrand <david@xxxxxxxxxx> wrote: > > > > On 27.02.24 10:07, Ryan Roberts wrote: > > > On 27/02/2024 02:40, Barry Song wrote: > > >> From: Barry Song <v-songbaohua@xxxxxxxx> > > >> > > >> madvise and some others might need folio_pte_batch to check if a range > > >> of PTEs are completely mapped to a large folio with contiguous physcial > > >> addresses. Let's export it for others to use. > > >> > > >> Cc: Lance Yang <ioworker0@xxxxxxxxx> > > >> Cc: Ryan Roberts <ryan.roberts@xxxxxxx> > > >> Cc: David Hildenbrand <david@xxxxxxxxxx> > > >> Cc: Yin Fengwei <fengwei.yin@xxxxxxxxx> > > >> Signed-off-by: Barry Song <v-songbaohua@xxxxxxxx> > > >> --- > > >> -v1: > > >> at least two jobs madv_free and madv_pageout depend on it. To avoid > > >> conflicts and dependencies, after discussing with Lance, we prefer > > >> this one can land earlier. > > > > > > I think this will also ultimately be useful for mprotect too, though I haven't > > > looked at it properly yet. > > > > > > > Yes, I think we briefly discussed that. > > > > >> > > >> mm/internal.h | 13 +++++++++++++ > > >> mm/memory.c | 11 +---------- > > >> 2 files changed, 14 insertions(+), 10 deletions(-) > > >> > > >> diff --git a/mm/internal.h b/mm/internal.h > > >> index 13b59d384845..8e2bc304f671 100644 > > >> --- a/mm/internal.h > > >> +++ b/mm/internal.h > > >> @@ -83,6 +83,19 @@ static inline void *folio_raw_mapping(struct folio *folio) > > >> return (void *)(mapping & ~PAGE_MAPPING_FLAGS); > > >> } > > >> > > >> +/* 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)) > > >> + > > >> +extern 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); > > >> + > > >> void __acct_reclaim_writeback(pg_data_t *pgdat, struct folio *folio, > > >> int nr_throttled); > > >> static inline void acct_reclaim_writeback(struct folio *folio) > > >> diff --git a/mm/memory.c b/mm/memory.c > > >> index 1c45b6a42a1b..319b3be05e75 100644 > > >> --- a/mm/memory.c > > >> +++ b/mm/memory.c > > >> @@ -953,15 +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) > > >> @@ -982,7 +973,7 @@ static inline pte_t __pte_batch_clear_ignored(pte_t pte, fpb_t flags) > > >> * If "any_writable" is set, it will indicate if any other PTE besides the > > >> * first (given) PTE is writable. > > >> */ > > > > > > David was talking in Lance's patch thread, about improving the docs for this > > > function now that its exported. Might be worth syncing on that. > > > > Here is my take: > > > > Signed-off-by: David Hildenbrand <david@xxxxxxxxxx> > > --- > > mm/memory.c | 22 ++++++++++++++++++---- > > 1 file changed, 18 insertions(+), 4 deletions(-) > > > > diff --git a/mm/memory.c b/mm/memory.c > > index d0b855a1837a8..098356b8805ae 100644 > > --- a/mm/memory.c > > +++ b/mm/memory.c > > @@ -971,16 +971,28 @@ static inline pte_t __pte_batch_clear_ignored(pte_t pte, fpb_t flags) > > 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. > > Nit: > > - * @pte: Page table entry for the first page. > + * @pte: Page table entry for the first page that must be the first subpage of > + * the folio excluding arm64 for now. > > IIUC, pte_batch_hint is always 1 excluding arm64 for now. > I'm not sure if this modification will be helpful? I don't understand how this will be different for arm64 and others. It seems pte_batch_hint with one value > 1 only helps move the PTE pointer faster to finish the call. Thanks Barry