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SubjectRe: [PATCH] mm/hugetlbfs: Unmap pages if page fault raced with hole punch
On Mon, 11 Jan 2016 19:21:15 -0800 Mike Kravetz <mike.kravetz@oracle.com> wrote:

> >> Just let me know what is easiest/best for you.
> >
> > If you're saying that
> > http://ozlabs.org/~akpm/mmots/broken-out/mm-mempolicy-skip-non-migratable-vmas-when-setting-mpol_mf_lazy.patch
>
> That should be,
> http://ozlabs.org/~akpm/mmots/broken-out/mm-hugetlbfs-fix-bugs-in-hugetlb_vmtruncate_list.patch

yup.

> > and
> > http://ozlabs.org/~akpm/mmots/broken-out/mm-hugetlbfs-unmap-pages-if-page-fault-raced-with-hole-punch.patch
> > are the final everything-works versions then we're all good to go now.
> >
>
> The only thing that 'might' be an issue is the new reference to
> hugetlb_vmdelete_list() from remove_inode_hugepages().
> hugetlb_vmdelete_list() was after remove_inode_hugepages() in the source
> file.
>
> The original patch moved hugetlb_vmdelete_list() to satisfy the new
> reference. I can not tell if that was taken into account in the way the
> patches were pulled into your tree. Will certainly know when it comes
> time to build.

um, yes.

--- a/fs/hugetlbfs/inode.c~mm-hugetlbfs-unmap-pages-if-page-fault-raced-with-hole-punch-fix
+++ a/fs/hugetlbfs/inode.c
@@ -324,6 +324,44 @@ static void remove_huge_page(struct page
delete_from_page_cache(page);
}

+static void
+hugetlb_vmdelete_list(struct rb_root *root, pgoff_t start, pgoff_t end)
+{
+ struct vm_area_struct *vma;
+
+ /*
+ * end == 0 indicates that the entire range after
+ * start should be unmapped.
+ */
+ vma_interval_tree_foreach(vma, root, start, end ? end : ULONG_MAX) {
+ unsigned long v_offset;
+ unsigned long v_end;
+
+ /*
+ * Can the expression below overflow on 32-bit arches?
+ * No, because the interval tree returns us only those vmas
+ * which overlap the truncated area starting at pgoff,
+ * and no vma on a 32-bit arch can span beyond the 4GB.
+ */
+ if (vma->vm_pgoff < start)
+ v_offset = (start - vma->vm_pgoff) << PAGE_SHIFT;
+ else
+ v_offset = 0;
+
+ if (!end)
+ v_end = vma->vm_end;
+ else {
+ v_end = ((end - vma->vm_pgoff) << PAGE_SHIFT)
+ + vma->vm_start;
+ if (v_end > vma->vm_end)
+ v_end = vma->vm_end;
+ }
+
+ unmap_hugepage_range(vma, vma->vm_start + v_offset, v_end,
+ NULL);
+ }
+}
+
/*
* remove_inode_hugepages handles two distinct cases: truncation and hole
* punch. There are subtle differences in operation for each case.
@@ -458,44 +496,6 @@ static void hugetlbfs_evict_inode(struct
clear_inode(inode);
}

-static inline void
-hugetlb_vmdelete_list(struct rb_root *root, pgoff_t start, pgoff_t end)
-{
- struct vm_area_struct *vma;
-
- /*
- * end == 0 indicates that the entire range after
- * start should be unmapped.
- */
- vma_interval_tree_foreach(vma, root, start, end ? end : ULONG_MAX) {
- unsigned long v_offset;
- unsigned long v_end;
-
- /*
- * Can the expression below overflow on 32-bit arches?
- * No, because the interval tree returns us only those vmas
- * which overlap the truncated area starting at pgoff,
- * and no vma on a 32-bit arch can span beyond the 4GB.
- */
- if (vma->vm_pgoff < start)
- v_offset = (start - vma->vm_pgoff) << PAGE_SHIFT;
- else
- v_offset = 0;
-
- if (!end)
- v_end = vma->vm_end;
- else {
- v_end = ((end - vma->vm_pgoff) << PAGE_SHIFT)
- + vma->vm_start;
- if (v_end > vma->vm_end)
- v_end = vma->vm_end;
- }
-
- unmap_hugepage_range(vma, vma->vm_start + v_offset, v_end,
- NULL);
- }
-}
-
static int hugetlb_vmtruncate(struct inode *inode, loff_t offset)
{
pgoff_t pgoff;
_
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