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authorGerald Schaefer <gerald.schaefer@de.ibm.com>2016-04-28 16:18:35 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2016-04-28 19:34:04 -0700
commit28093f9f34cedeaea0f481c58446d9dac6dd620f (patch)
treeda930385a854ae9cb95239b84fa9bac9b677c812 /fs
parent3486b85a29c1741db99d0c522211c82d2b7a56d0 (diff)
downloadlinux-28093f9f34cedeaea0f481c58446d9dac6dd620f.tar.bz2
numa: fix /proc/<pid>/numa_maps for THP
In gather_pte_stats() a THP pmd is cast into a pte, which is wrong because the layouts may differ depending on the architecture. On s390 this will lead to inaccurate numa_maps accounting in /proc because of misguided pte_present() and pte_dirty() checks on the fake pte. On other architectures pte_present() and pte_dirty() may work by chance, but there may be an issue with direct-access (dax) mappings w/o underlying struct pages when HAVE_PTE_SPECIAL is set and THP is available. In vm_normal_page() the fake pte will be checked with pte_special() and because there is no "special" bit in a pmd, this will always return false and the VM_PFNMAP | VM_MIXEDMAP checking will be skipped. On dax mappings w/o struct pages, an invalid struct page pointer would then be returned that can crash the kernel. This patch fixes the numa_maps THP handling by introducing new "_pmd" variants of the can_gather_numa_stats() and vm_normal_page() functions. Signed-off-by: Gerald Schaefer <gerald.schaefer@de.ibm.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com> Cc: Konstantin Khlebnikov <koct9i@gmail.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Jerome Marchand <jmarchan@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Michael Holzheu <holzheu@linux.vnet.ibm.com> Cc: <stable@vger.kernel.org> [4.3+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs')
-rw-r--r--fs/proc/task_mmu.c33
1 files changed, 30 insertions, 3 deletions
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 229cb546bee0..541583510cfb 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -1518,6 +1518,32 @@ static struct page *can_gather_numa_stats(pte_t pte, struct vm_area_struct *vma,
return page;
}
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+static struct page *can_gather_numa_stats_pmd(pmd_t pmd,
+ struct vm_area_struct *vma,
+ unsigned long addr)
+{
+ struct page *page;
+ int nid;
+
+ if (!pmd_present(pmd))
+ return NULL;
+
+ page = vm_normal_page_pmd(vma, addr, pmd);
+ if (!page)
+ return NULL;
+
+ if (PageReserved(page))
+ return NULL;
+
+ nid = page_to_nid(page);
+ if (!node_isset(nid, node_states[N_MEMORY]))
+ return NULL;
+
+ return page;
+}
+#endif
+
static int gather_pte_stats(pmd_t *pmd, unsigned long addr,
unsigned long end, struct mm_walk *walk)
{
@@ -1527,14 +1553,14 @@ static int gather_pte_stats(pmd_t *pmd, unsigned long addr,
pte_t *orig_pte;
pte_t *pte;
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
ptl = pmd_trans_huge_lock(pmd, vma);
if (ptl) {
- pte_t huge_pte = *(pte_t *)pmd;
struct page *page;
- page = can_gather_numa_stats(huge_pte, vma, addr);
+ page = can_gather_numa_stats_pmd(*pmd, vma, addr);
if (page)
- gather_stats(page, md, pte_dirty(huge_pte),
+ gather_stats(page, md, pmd_dirty(*pmd),
HPAGE_PMD_SIZE/PAGE_SIZE);
spin_unlock(ptl);
return 0;
@@ -1542,6 +1568,7 @@ static int gather_pte_stats(pmd_t *pmd, unsigned long addr,
if (pmd_trans_unstable(pmd))
return 0;
+#endif
orig_pte = pte = pte_offset_map_lock(walk->mm, pmd, addr, &ptl);
do {
struct page *page = can_gather_numa_stats(*pte, vma, addr);