[PATCH 7/8] HWPOISON, hugetlb: detect hwpoison in hugetlb code
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From: Naoya Horiguchi on 27 May 2010 20:40 This patch enables to block access to hwpoisoned hugepage and also enables to block unmapping for it. Dependency: "HWPOISON, hugetlb: enable error handling path for hugepage" Signed-off-by: Naoya Horiguchi <n-horiguchi(a)ah.jp.nec.com> Cc: Andi Kleen <andi(a)firstfloor.org> Cc: Andrew Morton <akpm(a)linux-foundation.org> Cc: Wu Fengguang <fengguang.wu(a)intel.com> --- mm/hugetlb.c | 40 ++++++++++++++++++++++++++++++++++++++++ 1 files changed, 40 insertions(+), 0 deletions(-) diff --git v2.6.34/mm/hugetlb.c v2.6.34/mm/hugetlb.c index aaba3cc..5580568 100644 --- v2.6.34/mm/hugetlb.c +++ v2.6.34/mm/hugetlb.c @@ -19,6 +19,8 @@ #include <linux/sysfs.h> #include <linux/slab.h> #include <linux/rmap.h> +#include <linux/swap.h> +#include <linux/swapops.h> #include <asm/page.h> #include <asm/pgtable.h> @@ -2145,6 +2147,19 @@ nomem: return -ENOMEM; } +static int is_hugetlb_entry_hwpoisoned(pte_t pte) +{ + swp_entry_t swp; + + if (huge_pte_none(pte) || pte_present(pte)) + return 0; + swp = pte_to_swp_entry(pte); + if (non_swap_entry(swp) && is_hwpoison_entry(swp)) { + return 1; + } else + return 0; +} + void __unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start, unsigned long end, struct page *ref_page) { @@ -2203,6 +2218,12 @@ void __unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start, if (huge_pte_none(pte)) continue; + /* + * HWPoisoned hugepage is already unmapped and dropped reference + */ + if (unlikely(is_hugetlb_entry_hwpoisoned(pte))) + continue; + page = pte_page(pte); if (pte_dirty(pte)) set_page_dirty(page); @@ -2487,6 +2508,18 @@ retry: } /* + * Since memory error handler replaces pte into hwpoison swap entry + * at the time of error handling, a process which reserved but not have + * the mapping to the error hugepage does not have hwpoison swap entry. + * So we need to block accesses from such a process by checking + * PG_hwpoison bit here. + */ + if (unlikely(PageHWPoison(page))) { + ret = VM_FAULT_HWPOISON; + goto backout_unlocked; + } + + /* * If we are going to COW a private mapping later, we examine the * pending reservations for this page now. This will ensure that * any allocations necessary to record that reservation occur outside @@ -2540,6 +2573,13 @@ int hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma, static DEFINE_MUTEX(hugetlb_instantiation_mutex); struct hstate *h = hstate_vma(vma); + ptep = huge_pte_offset(mm, address); + if (ptep) { + entry = huge_ptep_get(ptep); + if (unlikely(is_hugetlb_entry_hwpoisoned(entry))) + return VM_FAULT_HWPOISON; + } + ptep = huge_pte_alloc(mm, address, huge_page_size(h)); if (!ptep) return VM_FAULT_OOM; -- 1.7.0 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |