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authorHugh Dickins <hugh@veritas.com>2005-10-20 16:24:28 +0100
committerLinus Torvalds <torvalds@g5.osdl.org>2005-10-20 09:02:07 -0700
commitac9b9c667c2e1194e22ebe0a441ae1c37aaa9b90 (patch)
tree3903d87d0b56a49ead39c0460b5bc0b86b040775
parent93918e9afc76717176e9e114e79cdbb602a45ae8 (diff)
downloadop-kernel-dev-ac9b9c667c2e1194e22ebe0a441ae1c37aaa9b90.zip
op-kernel-dev-ac9b9c667c2e1194e22ebe0a441ae1c37aaa9b90.tar.gz
[PATCH] Fix handling spurious page fault for hugetlb region
This reverts commit 3359b54c8c07338f3a863d1109b42eebccdcf379 and replaces it with a cleaner version that is purely based on page table operations, so that the synchronization between inode size and hugetlb mappings becomes moot. Signed-off-by: Hugh Dickins <hugh@veritas.com> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
-rw-r--r--include/linux/hugetlb.h16
-rw-r--r--mm/hugetlb.c22
-rw-r--r--mm/memory.c14
3 files changed, 27 insertions, 25 deletions
diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index 42cb7d70..d664330 100644
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -25,6 +25,8 @@ int is_hugepage_mem_enough(size_t);
unsigned long hugetlb_total_pages(void);
struct page *alloc_huge_page(void);
void free_huge_page(struct page *);
+int hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma,
+ unsigned long address, int write_access);
extern unsigned long max_huge_pages;
extern const unsigned long hugetlb_zero, hugetlb_infinity;
@@ -99,6 +101,7 @@ static inline unsigned long hugetlb_total_pages(void)
do { } while (0)
#define alloc_huge_page() ({ NULL; })
#define free_huge_page(p) ({ (void)(p); BUG(); })
+#define hugetlb_fault(mm, vma, addr, write) ({ BUG(); 0; })
#ifndef HPAGE_MASK
#define HPAGE_MASK 0 /* Keep the compiler happy */
@@ -155,24 +158,11 @@ static inline void set_file_hugepages(struct file *file)
{
file->f_op = &hugetlbfs_file_operations;
}
-
-static inline int valid_hugetlb_file_off(struct vm_area_struct *vma,
- unsigned long address)
-{
- struct inode *inode = vma->vm_file->f_dentry->d_inode;
- loff_t file_off = address - vma->vm_start;
-
- file_off += (vma->vm_pgoff << PAGE_SHIFT);
-
- return (file_off < inode->i_size);
-}
-
#else /* !CONFIG_HUGETLBFS */
#define is_file_hugepages(file) 0
#define set_file_hugepages(file) BUG()
#define hugetlb_zero_setup(size) ERR_PTR(-ENOSYS)
-#define valid_hugetlb_file_off(vma, address) 0
#endif /* !CONFIG_HUGETLBFS */
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index a1b30d4..61d3806 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -394,6 +394,28 @@ out:
return ret;
}
+/*
+ * On ia64 at least, it is possible to receive a hugetlb fault from a
+ * stale zero entry left in the TLB from earlier hardware prefetching.
+ * Low-level arch code should already have flushed the stale entry as
+ * part of its fault handling, but we do need to accept this minor fault
+ * and return successfully. Whereas the "normal" case is that this is
+ * an access to a hugetlb page which has been truncated off since mmap.
+ */
+int hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma,
+ unsigned long address, int write_access)
+{
+ int ret = VM_FAULT_SIGBUS;
+ pte_t *pte;
+
+ spin_lock(&mm->page_table_lock);
+ pte = huge_pte_offset(mm, address);
+ if (pte && !pte_none(*pte))
+ ret = VM_FAULT_MINOR;
+ spin_unlock(&mm->page_table_lock);
+ return ret;
+}
+
int follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma,
struct page **pages, struct vm_area_struct **vmas,
unsigned long *position, int *length, int i)
diff --git a/mm/memory.c b/mm/memory.c
index 8c88b97..1db40e9 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2045,18 +2045,8 @@ int __handle_mm_fault(struct mm_struct *mm, struct vm_area_struct * vma,
inc_page_state(pgfault);
- 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. */
- }
+ if (unlikely(is_vm_hugetlb_page(vma)))
+ return hugetlb_fault(mm, vma, address, write_access);
/*
* We need the page table lock to synchronize with kswapd
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