From 3359b54c8c07338f3a863d1109b42eebccdcf379 Mon Sep 17 00:00:00 2001 From: "Seth, Rohit" Date: Tue, 18 Oct 2005 14:15:12 -0700 Subject: [PATCH] Handle spurious page fault for hugetlb region The hugetlb pages are currently pre-faulted. At the time of mmap of hugepages, we populate the new PTEs. It is possible that HW has already cached some of the unused PTEs internally. These stale entries never get a chance to be purged in existing control flow. This patch extends the check in page fault code for hugepages. Check if a faulted address falls with in size for the hugetlb file backing it. We return VM_FAULT_MINOR for these cases (assuming that the arch specific page-faulting code purges the stale entry for the archs that need it). Signed-off-by: Rohit Seth [ This is apparently arguably an ia64 port bug. But the code won't hurt, and for now it fixes a real problem on some ia64 machines ] Signed-off-by: Linus Torvalds --- mm/memory.c | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 deletions(-) (limited to 'mm/memory.c') diff --git a/mm/memory.c b/mm/memory.c index ae8161f1f459..8c88b973abc5 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -2045,8 +2045,18 @@ int __handle_mm_fault(struct mm_struct *mm, struct vm_area_struct * vma, inc_page_state(pgfault); - if (is_vm_hugetlb_page(vma)) - return VM_FAULT_SIGBUS; /* mapping truncation does this. */ + if (unlikely(is_vm_hugetlb_page(vma))) { + if (valid_hugetlb_file_off(vma, address)) + /* We get here only if there was a stale(zero) TLB entry + * (because of HW prefetching). + * Low-level arch code (if needed) should have already + * purged the stale entry as part of this fault handling. + * Here we just return. + */ + return VM_FAULT_MINOR; + else + return VM_FAULT_SIGBUS; /* mapping truncation does this. */ + } /* * We need the page table lock to synchronize with kswapd -- cgit v1.2.1