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[PATCH] Fix handling spurious page fault for hugetlb region

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This reverts commit 3359b54c8c 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>
This commit is contained in:
Hugh Dickins 2005-10-20 16:24:28 +01:00 committed by Linus Torvalds
parent 93918e9afc
commit ac9b9c667c
3 changed files with 27 additions and 25 deletions
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16
include/linux/hugetlb.h
View file

@ -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 */

22
mm/hugetlb.c
View file

@ -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)

14
mm/memory.c
View file

@ -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