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[PATCH] Handle spurious page fault for hugetlb region

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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 <rohit.seth@intel.com>

[ 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 <torvalds@osdl.org>
This commit is contained in:
Seth, Rohit 2005-10-18 14:15:12 -07:00 • committed by Linus Torvalds
parent bb7e257ef8
commit 3359b54c8c
2 changed files with 25 additions and 2 deletions
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13
include/linux/hugetlb.h
View file

@ -155,11 +155,24 @@ 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 */