Re: [PATCH v12 2/5] fs/proc/task_mmu: Implement IOCTL to get and optionally clear info about PTEs

On Thu, 6 Apr 2023 at 09:40, Muhammad Usama Anjum usama.anjum@collabora.com wrote: [...]

--- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c

[...]

+static int pagemap_scan_pmd_entry(pmd_t *pmd, unsigned long start,

•                             unsigned long end, struct mm_walk *walk)
  

+{

•   struct pagemap_scan_private *p = walk->private;
  

•   bool is_written, is_file, is_present, is_swap;
  

•   struct vm_area_struct *vma = walk->vma;
  

•   unsigned long addr = end;
  

•   spinlock_t *ptl;
  

•   int ret = 0;
  

•   pte_t *pte;
  

+#ifdef CONFIG_TRANSPARENT_HUGEPAGE

•   ptl = pmd_trans_huge_lock(pmd, vma);
  

•   if (ptl) {
  

[...]

•           return ret;
  

•   }
  

+process_smaller_pages:

•   if (pmd_trans_unstable(pmd))
  

•           return 0;
  

Why pmd_trans_unstable() is needed here and not only after split_huge_pmd()?

Best regards Michał Mirosław