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| author | Seth, Rohit <rohit.seth@intel.com> | 2005-10-19 01:15:12 +0400 |
|---|---|---|
| committer | Linus Torvalds <torvalds@g5.osdl.org> | 2005-10-20 00:56:27 +0400 |
| commit | 3359b54c8c07338f3a863d1109b42eebccdcf379 (patch) | |
| tree | f91edd52c71e57ce4b46e3875c9054666ca4e24c | |
| parent | bb7e257ef8d8ba43cab356aa1cc1b20d0106d45f (diff) | |
| download | linux-3359b54c8c07338f3a863d1109b42eebccdcf379.tar.xz | |
[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 <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>
| -rw-r--r-- | include/linux/hugetlb.h | 13 | ||||
| -rw-r--r-- | mm/memory.c | 14 |
2 files changed, 25 insertions, 2 deletions
diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h index e670b0d13fe0..42cb7d70f9ac 100644 --- a/include/linux/hugetlb.h +++ b/include/linux/hugetlb.h @@ -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 */ 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 |