| From | Greg Kroah-Hartman <> | Subject | [PATCH 4.4 111/137] numa: fix /proc/<pid>/numa_maps for hugetlbfs on s390 | Date | Tue, 23 Feb 2016 19:34:02 -0800 |
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4.4-stable review patch. If anyone has any objections, please let me know.
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From: Michael Holzheu <holzheu@linux.vnet.ibm.com>
commit 5c2ff95e41c9290d16556cd02e35b25d81be8fe0 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>
--- fs/proc/task_mmu.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-)
--- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -1473,18 +1473,19 @@ static int gather_pte_stats(pmd_t *pmd, 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; }
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