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Encode huge page size for VM_FAULT_HWPOISON errors

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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 <n-horiguchi@ah.jp.nec.com>
Cc: fengguang.wu@intel.com
Signed-off-by: Andi Kleen <ak@linux.intel.com>
This commit is contained in:
Andi Kleen
2010-10-06 21:45:00 +02:00
parent 6f39ce056a
commit aa50d3a7aa
4 changed files with 22 additions and 5 deletions
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6
include/linux/hugetlb.h
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@ -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 */