On 4/21/26 13:12, David Hildenbrand (Arm) wrote: > On 4/21/26 12:58, David Hildenbrand (Arm) wrote: >> On 4/20/26 14:50, Michael S. Tsirkin wrote: >>> Use vma_alloc_folio_hints() and check PGHINT_ZEROED to skip >>> clear_user_highpage() when the page is already zeroed. >>> >>> On x86, vma_alloc_zeroed_movable_folio is overridden by a macro >>> that uses __GFP_ZERO directly, so this change has no effect there. >>> >>> Signed-off-by: Michael S. Tsirkin <[email protected]> >>> Assisted-by: Claude:claude-opus-4-6 >>> Assisted-by: cursor-agent:GPT-5.4-xhigh >>> --- >>> include/linux/highmem.h | 6 ++++-- >>> 1 file changed, 4 insertions(+), 2 deletions(-) >>> >>> diff --git a/include/linux/highmem.h b/include/linux/highmem.h >>> index af03db851a1d..8bb67772c1cb 100644 >>> --- a/include/linux/highmem.h >>> +++ b/include/linux/highmem.h >>> @@ -321,9 +321,11 @@ struct folio *vma_alloc_zeroed_movable_folio(struct >>> vm_area_struct *vma, >>> unsigned long vaddr) >>> { >>> struct folio *folio; >>> + pghint_t hints; >>> >>> - folio = vma_alloc_folio(GFP_HIGHUSER_MOVABLE, 0, vma, vaddr); >>> - if (folio && user_alloc_needs_zeroing()) >>> + folio = vma_alloc_folio_hints(GFP_HIGHUSER_MOVABLE, 0, vma, vaddr, >>> + &hints); >>> + if (folio && user_alloc_needs_zeroing() && !(hints & PGHINT_ZEROED)) >>> clear_user_highpage(&folio->page, vaddr); >>> >>> return folio; >> >> >> For others reading along, the variant on your other branch: >> >> diff --git a/include/linux/highmem.h b/include/linux/highmem.h >> index af03db851a1d9..ffa683f64f1d1 100644 >> --- a/include/linux/highmem.h >> +++ b/include/linux/highmem.h >> @@ -320,13 +320,8 @@ static inline >> struct folio *vma_alloc_zeroed_movable_folio(struct vm_area_struct *vma, >> unsigned long vaddr) >> { >> - struct folio *folio; >> - >> - folio = vma_alloc_folio(GFP_HIGHUSER_MOVABLE, 0, vma, vaddr); >> - if (folio && user_alloc_needs_zeroing()) >> - clear_user_highpage(&folio->page, vaddr); >> - >> - return folio; >> + return vma_alloc_folio(GFP_HIGHUSER_MOVABLE | __GFP_ZERO, >> + 0, vma, vaddr); >> } >> #endif >> >> Looks like an extremely clean interface. >> > > And we could likely just do the following on top I assume. > > diff --git a/arch/m68k/include/asm/page_no.h b/arch/m68k/include/asm/page_no.h > index d2532bc407ef..f511b763a235 100644 > --- a/arch/m68k/include/asm/page_no.h > +++ b/arch/m68k/include/asm/page_no.h > @@ -12,9 +12,6 @@ extern unsigned long memory_end; > > #define copy_user_page(to, from, vaddr, pg) copy_page(to, from) > > -#define vma_alloc_zeroed_movable_folio(vma, vaddr) \ > - vma_alloc_folio(GFP_HIGHUSER_MOVABLE | __GFP_ZERO, 0, vma, vaddr) > - > #define __pa(vaddr) ((unsigned long)(vaddr)) > #define __va(paddr) ((void *)((unsigned long)(paddr))) > > diff --git a/arch/s390/include/asm/page.h b/arch/s390/include/asm/page.h > index 56da819a79e6..e995d2a413f9 100644 > --- a/arch/s390/include/asm/page.h > +++ b/arch/s390/include/asm/page.h > @@ -67,9 +67,6 @@ static inline void copy_page(void *to, void *from) > > #define copy_user_page(to, from, vaddr, pg) copy_page(to, from) > > -#define vma_alloc_zeroed_movable_folio(vma, vaddr) \ > - vma_alloc_folio(GFP_HIGHUSER_MOVABLE | __GFP_ZERO, 0, vma, vaddr) > - > #ifdef CONFIG_STRICT_MM_TYPECHECKS > #define STRICT_MM_TYPECHECKS > #endif > diff --git a/arch/x86/include/asm/page.h b/arch/x86/include/asm/page.h > index 416dc88e35c1..92fa975b46f3 100644 > --- a/arch/x86/include/asm/page.h > +++ b/arch/x86/include/asm/page.h > @@ -28,9 +28,6 @@ static inline void copy_user_page(void *to, void *from, > unsigned long vaddr, > copy_page(to, from); > } > > -#define vma_alloc_zeroed_movable_folio(vma, vaddr) \ > - vma_alloc_folio(GFP_HIGHUSER_MOVABLE | __GFP_ZERO, 0, vma, vaddr) > - > #ifndef __pa > #define __pa(x) __phys_addr((unsigned long)(x)) > #endif > >
... and I wonder whether we could then convert the arm64 variant into a simple helper that just returns additional gfp flags. We might even be able to call that from inside vma_alloc_folio(), to just get __GFP_ZEROTAGS whenever the VMA has VM_MTE. But that's obviously some additional work on top. -- Cheers, David
