From aa50d3a7aa8147b9e14dc9d5972a5d2359db4ef8 Mon Sep 17 00:00:00 2001 From: Andi Kleen Date: Wed, 6 Oct 2010 21:45:00 +0200 Subject: [PATCH] Encode huge page size for VM_FAULT_HWPOISON errors This fixes a problem introduced with the hugetlb hwpoison handling The user space SIGBUS signalling wants to know the size of the hugepage that caused a HWPOISON fault. Unfortunately the architecture page fault handlers do not have easy access to the struct page. Pass the information out in the fault error code instead. I added a separate VM_FAULT_HWPOISON_LARGE bit for this case and encode the hpage index in some free upper bits of the fault code. The small page hwpoison keeps stays with the VM_FAULT_HWPOISON name to minimize changes. Also add code to hugetlb.h to convert that index into a page shift. Will be used in a further patch. Cc: Naoya Horiguchi Cc: fengguang.wu@intel.com Signed-off-by: Andi Kleen --- include/linux/hugetlb.h | 6 ++++++ include/linux/mm.h | 12 ++++++++++-- mm/hugetlb.c | 6 ++++-- mm/memory.c | 3 ++- 4 files changed, 22 insertions(+), 5 deletions(-) diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h index 796f30e00806..943c76b3d4bb 100644 --- a/include/linux/hugetlb.h +++ b/include/linux/hugetlb.h @@ -307,6 +307,11 @@ static inline struct hstate *page_hstate(struct page *page) return size_to_hstate(PAGE_SIZE << compound_order(page)); } +static inline unsigned hstate_index_to_shift(unsigned index) +{ + return hstates[index].order + PAGE_SHIFT; +} + #else struct hstate {}; #define alloc_huge_page_node(h, nid) NULL @@ -324,6 +329,7 @@ static inline unsigned int pages_per_huge_page(struct hstate *h) { return 1; } +#define hstate_index_to_shift(index) 0 #endif #endif /* _LINUX_HUGETLB_H */ diff --git a/include/linux/mm.h b/include/linux/mm.h index 74949fbef8c6..f7e9efc6720b 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -718,12 +718,20 @@ static inline int page_mapped(struct page *page) #define VM_FAULT_SIGBUS 0x0002 #define VM_FAULT_MAJOR 0x0004 #define VM_FAULT_WRITE 0x0008 /* Special case for get_user_pages */ -#define VM_FAULT_HWPOISON 0x0010 /* Hit poisoned page */ +#define VM_FAULT_HWPOISON 0x0010 /* Hit poisoned small page */ +#define VM_FAULT_HWPOISON_LARGE 0x0020 /* Hit poisoned large page. Index encoded in upper bits */ #define VM_FAULT_NOPAGE 0x0100 /* ->fault installed the pte, not return page */ #define VM_FAULT_LOCKED 0x0200 /* ->fault locked the returned page */ -#define VM_FAULT_ERROR (VM_FAULT_OOM | VM_FAULT_SIGBUS | VM_FAULT_HWPOISON) +#define VM_FAULT_HWPOISON_LARGE_MASK 0xf000 /* encodes hpage index for large hwpoison */ + +#define VM_FAULT_ERROR (VM_FAULT_OOM | VM_FAULT_SIGBUS | VM_FAULT_HWPOISON | \ + VM_FAULT_HWPOISON_LARGE) + +/* Encode hstate index for a hwpoisoned large page */ +#define VM_FAULT_SET_HINDEX(x) ((x) << 12) +#define VM_FAULT_GET_HINDEX(x) (((x) >> 12) & 0xf) /* * Can be called by the pagefault handler when it gets a VM_FAULT_OOM. diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 67cd03239b75..96991ded82fe 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -2589,7 +2589,8 @@ retry: * So we need to block hugepage fault by PG_hwpoison bit check. */ if (unlikely(PageHWPoison(page))) { - ret = VM_FAULT_HWPOISON; + ret = VM_FAULT_HWPOISON | + VM_FAULT_SET_HINDEX(h - hstates); goto backout_unlocked; } page_dup_rmap(page); @@ -2656,7 +2657,8 @@ int hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma, migration_entry_wait(mm, (pmd_t *)ptep, address); return 0; } else if (unlikely(is_hugetlb_entry_hwpoisoned(entry))) - return VM_FAULT_HWPOISON; + return VM_FAULT_HWPOISON_LARGE | + VM_FAULT_SET_HINDEX(h - hstates); } ptep = huge_pte_alloc(mm, address, huge_page_size(h)); diff --git a/mm/memory.c b/mm/memory.c index 0e18b4d649ec..c2d6dd315659 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -1450,7 +1450,8 @@ int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm, if (ret & VM_FAULT_OOM) return i ? i : -ENOMEM; if (ret & - (VM_FAULT_HWPOISON|VM_FAULT_SIGBUS)) + (VM_FAULT_HWPOISON|VM_FAULT_HWPOISON_LARGE| + VM_FAULT_SIGBUS)) return i ? i : -EFAULT; BUG(); }