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Shutemov" , Matthew Wilcox , Andrew Morton , Linux MM , Linux Kernel Mailing List Content-Type: text/plain; charset="UTF-8" ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1654880395; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=6oCcDIZ6NGhYZEWuS6OCQMXStNToq7DhXXPf8Kj6NnM=; b=o05WLLmnYu5iA2AJhMIrTWGodokGVASA7ug1m4rgmgYgA9C0iPaWpq+2Kq87Rc2Ae+siwb 9J7+CxrEc60je86aKZBXbzYOHBULV+L3Nhbp2YviCE+VJSCUaAvr81V7Eeu9EL5m0dnO2q FXzY2Yo/UFqyRgammjAnCnTtNq+VCRg= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1654880395; a=rsa-sha256; cv=none; b=wkR6UgRoh9jmh777kh6YyULGgTqd1IGkWlPaxw0/bvROgyry6IjpmUKpvEqHk/9ygiEGTn rGzPDiev3wFmzI/BEvWnyEbPN2EIjQeubppG4X8t5Dr42+KIZdtmzmmmJjFYJvnsFLpzZM PzWuXpps6l+uD2EAUl5tEHCgNYECj0s= ARC-Authentication-Results: i=1; imf26.hostedemail.com; dkim=pass header.d=gmail.com header.s=20210112 header.b=lqwHwach; dmarc=pass (policy=none) header.from=gmail.com; spf=pass (imf26.hostedemail.com: domain of shy828301@gmail.com designates 209.85.210.181 as permitted sender) smtp.mailfrom=shy828301@gmail.com Authentication-Results: imf26.hostedemail.com; dkim=pass header.d=gmail.com header.s=20210112 header.b=lqwHwach; dmarc=pass (policy=none) header.from=gmail.com; spf=pass (imf26.hostedemail.com: domain of shy828301@gmail.com designates 209.85.210.181 as permitted sender) smtp.mailfrom=shy828301@gmail.com X-Rspamd-Server: rspam08 X-Rspam-User: X-Stat-Signature: 7u4yy61txxyiik8ef177endw6taqjf61 X-Rspamd-Queue-Id: AF9E5140066 X-HE-Tag: 1654880395-100496 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 Thu, Jun 9, 2022 at 6:52 PM Zach O'Keefe wrote: > > 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 Yeah, you are right. > 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. I'm not fully sure I understand this 100%. I think this is related to how page cache is structured. I will try to add more comments. > > Also I wonder while we're at it if we can rename this to > transhuge_addr_aligned() or transhuge_addr_suitable() or something. I think it is still actually used to check vma. > > 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 > > > >