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Commit ac9b9c66 authored by Hugh Dickins's avatar Hugh Dickins Committed by Linus Torvalds
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[PATCH] Fix handling spurious page fault for hugetlb region 



This reverts commit 3359b54c 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: default avatarHugh Dickins <hugh@veritas.com>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 93918e9a

include/linux/hugetlb.h

+3 −13
Original line number Original line Diff line number Diff line
@@ -25,6 +25,8 @@ int is_hugepage_mem_enough(size_t); 
unsigned long hugetlb_total_pages(void);

unsigned long hugetlb_total_pages(void);

struct page *alloc_huge_page(void);

struct page *alloc_huge_page(void);

void free_huge_page(struct page *);

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 unsigned long max_huge_pages;

extern const unsigned long hugetlb_zero, hugetlb_infinity;

extern const unsigned long hugetlb_zero, hugetlb_infinity;
@@ -99,6 +101,7 @@ static inline unsigned long hugetlb_total_pages(void) 
						do { } while (0)

						do { } while (0)

#define alloc_huge_page()			({ NULL; })

#define alloc_huge_page()			({ NULL; })

#define free_huge_page(p)			({ (void)(p); BUG(); })

#define free_huge_page(p)			({ (void)(p); BUG(); })

#define hugetlb_fault(mm, vma, addr, write)	({ BUG(); 0; })





#ifndef HPAGE_MASK

#ifndef HPAGE_MASK

#define HPAGE_MASK	0		/* Keep the compiler happy */

#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;

	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 */

#else /* !CONFIG_HUGETLBFS */





#define is_file_hugepages(file)		0

#define is_file_hugepages(file)		0

#define set_file_hugepages(file)	BUG()

#define set_file_hugepages(file)	BUG()

#define hugetlb_zero_setup(size)	ERR_PTR(-ENOSYS)

#define hugetlb_zero_setup(size)	ERR_PTR(-ENOSYS)

#define valid_hugetlb_file_off(vma, address) 	0





#endif /* !CONFIG_HUGETLBFS */

#endif /* !CONFIG_HUGETLBFS */

mm/hugetlb.c

+22 −0
Original line number Original line Diff line number Diff line
@@ -394,6 +394,28 @@ int hugetlb_prefault(struct address_space *mapping, struct vm_area_struct *vma) 
	return ret;

	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,

int follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma,

			struct page **pages, struct vm_area_struct **vmas,

			struct page **pages, struct vm_area_struct **vmas,

			unsigned long *position, int *length, int i)

			unsigned long *position, int *length, int i)

mm/memory.c

+2 −12
Original line number Original line Diff line number Diff line
@@ -2045,18 +2045,8 @@ int __handle_mm_fault(struct mm_struct *mm, struct vm_area_struct * vma, 




	inc_page_state(pgfault);

	inc_page_state(pgfault);





	if (unlikely(is_vm_hugetlb_page(vma))) {

	if (unlikely(is_vm_hugetlb_page(vma)))

		if (valid_hugetlb_file_off(vma, address))

		return hugetlb_fault(mm, vma, address, write_access);

			/* 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

	 * We need the page table lock to synchronize with kswapd