lkml.org 
[lkml]   [2019]   [Aug]   [6]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH v4 1/2] khugepaged: enable collapse pmd for pte-mapped THP
On 08/02, Song Liu wrote:
>
> +void collapse_pte_mapped_thp(struct mm_struct *mm, unsigned long addr)
> +{
> + unsigned long haddr = addr & HPAGE_PMD_MASK;
> + struct vm_area_struct *vma = find_vma(mm, haddr);
> + pmd_t *pmd = mm_find_pmd(mm, haddr);
> + struct page *hpage = NULL;
> + spinlock_t *ptl;
> + int count = 0;
> + pmd_t _pmd;
> + int i;
> +
> + if (!vma || !vma->vm_file || !pmd ||
> + vma->vm_start > haddr || vma->vm_end < haddr + HPAGE_PMD_SIZE)
> + return;

I still can't understand why is it safe to blindly use mm_find_pmd().

Say, what pmd_offset(pud, address) will return to this function if
pud_huge() == T? IIUC, this is possible if is_file_hugepages(vm_file).
How the code below can use this result?

I think you need something like hugepage_vma_check() or even
hugepage_vma_revalidate().

Oleg.

\
 
 \ /
  Last update: 2019-08-06 12:03    [W:0.086 / U:3.464 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site