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dkim=pass header.d=google.com header.s=20210112 header.b=HCmGBSWP; dmarc=pass (policy=reject) header.from=google.com; spf=pass (imf01.hostedemail.com: domain of zokeefe@google.com designates 209.85.167.44 as permitted sender) smtp.mailfrom=zokeefe@google.com X-HE-Tag: 1654825929-728809 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Mon, Jun 6, 2022 at 2:44 PM Yang Shi wrote: > > The hugepage_vma_revalidate() needs to check if the address is still in > the aligned HPAGE_PMD_SIZE area of the vma when reacquiring mmap_lock, > but it was open-coded, use transhuge_vma_suitable() to do the job. And > add proper comments for transhuge_vma_suitable(). > > Signed-off-by: Yang Shi > --- > include/linux/huge_mm.h | 6 ++++++ > mm/khugepaged.c | 5 +---- > 2 files changed, 7 insertions(+), 4 deletions(-) > > diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h > index a8f61db47f2a..79d5919beb83 100644 > --- a/include/linux/huge_mm.h > +++ b/include/linux/huge_mm.h > @@ -128,6 +128,12 @@ static inline bool transhuge_vma_size_ok(struct vm_area_struct *vma) > return false; > } > > +/* > + * Do the below checks: > + * - For non-anon vma, check if the vm_pgoff is HPAGE_PMD_NR aligned. > + * - For all vmas, check if the haddr is in an aligned HPAGE_PMD_SIZE > + * area. > + */ AFAIK we aren't checking if vm_pgoff is HPAGE_PMD_NR aligned, but rather that linear_page_index(vma, round_up(vma->vm_start, HPAGE_PMD_SIZE)) is HPAGE_PMD_NR aligned within vma->vm_file. I was pretty confused about this (hopefully I have it right now - if not - case and point :) ), so it might be a good opportunity to add some extra commentary to help future travelers understand why this constraint exists. Also I wonder while we're at it if we can rename this to transhuge_addr_aligned() or transhuge_addr_suitable() or something. Otherwise I think the change is a nice cleanup. > static inline bool transhuge_vma_suitable(struct vm_area_struct *vma, > unsigned long addr) > { > diff --git a/mm/khugepaged.c b/mm/khugepaged.c > index 7a5d1c1a1833..ca1754d3a827 100644 > --- a/mm/khugepaged.c > +++ b/mm/khugepaged.c > @@ -951,7 +951,6 @@ static int hugepage_vma_revalidate(struct mm_struct *mm, unsigned long address, > struct vm_area_struct **vmap) > { > struct vm_area_struct *vma; > - unsigned long hstart, hend; > > if (unlikely(khugepaged_test_exit(mm))) > return SCAN_ANY_PROCESS; > @@ -960,9 +959,7 @@ static int hugepage_vma_revalidate(struct mm_struct *mm, unsigned long address, > if (!vma) > return SCAN_VMA_NULL; > > - hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK; > - hend = vma->vm_end & HPAGE_PMD_MASK; > - if (address < hstart || address + HPAGE_PMD_SIZE > hend) > + if (!transhuge_vma_suitable(vma, address)) > return SCAN_ADDRESS_RANGE; > if (!hugepage_vma_check(vma, vma->vm_flags)) > return SCAN_VMA_CHECK; > -- > 2.26.3 > >