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numa: fix /proc/<pid>/numa_maps for hugetlbfs on s390

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commit 5c2ff95e41 upstream.

When working with hugetlbfs ptes (which are actually pmds) is not valid to
directly use pte functions like pte_present() because the hardware bit
layout of pmds and ptes can be different.  This is the case on s390.
Therefore we have to convert the hugetlbfs ptes first into a valid pte
encoding with huge_ptep_get().

Currently the /proc/<pid>/numa_maps code uses hugetlbfs ptes without
huge_ptep_get().  On s390 this leads to the following two problems:

1) The pte_present() function returns false (instead of true) for
   PROT_NONE hugetlb ptes. Therefore PROT_NONE vmas are missing
   completely in the "numa_maps" output.

2) The pte_dirty() function always returns false for all hugetlb ptes.
   Therefore these pages are reported as "mapped=xxx" instead of
   "dirty=xxx".

Therefore use huge_ptep_get() to correctly convert the hugetlb ptes.

Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Reviewed-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Michael Holzheu
2016-02-02 16:57:26 -08:00
committed by Greg Kroah-Hartman
parent db33368ca3
commit 4b20545910
1 changed files with 4 additions and 3 deletions
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7
fs/proc/task_mmu.c
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@@ -1473,18 +1473,19 @@ static int gather_pte_stats(pmd_t *pmd, unsigned long addr,
static int gather_hugetlb_stats(pte_t *pte, unsigned long hmask,
unsigned long addr, unsigned long end, struct mm_walk *walk)
{
pte_t huge_pte = huge_ptep_get(pte);
struct numa_maps *md;
struct page *page;
if (!pte_present(*pte))
if (!pte_present(huge_pte))
return 0;
page = pte_page(*pte);
page = pte_page(huge_pte);
if (!page)
return 0;
md = walk->private;
gather_stats(page, md, pte_dirty(*pte), 1);
gather_stats(page, md, pte_dirty(huge_pte), 1);
return 0;
}