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| author | Toshi Kani <toshi.kani@hpe.com> | 2016-01-16 01:56:05 +0100 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2016-01-16 02:56:32 +0100 |
| commit | 59bf4fb9d386601cbaa70a9b00159abb846dedaa (patch) | |
| tree | 0735bb6400f6ed0a3c3be69e1e10018a17fe6a63 /fs/dax.c | |
| parent | mm, dax: fix livelock, allow dax pmd mappings to become writeable (diff) | |
| download | linux-59bf4fb9d386601cbaa70a9b00159abb846dedaa.tar.xz linux-59bf4fb9d386601cbaa70a9b00159abb846dedaa.zip | |
dax: Split pmd map when fallback on COW
An infinite loop of PMD faults was observed when attempted to mlock() a
private read-only PMD mmap'd range of a DAX file.
__dax_pmd_fault() simply returns with VM_FAULT_FALLBACK when falling
back to PTE on COW. However, __handle_mm_fault() returns without
falling back to handle_pte_fault() because a PMD map is present in this
case.
Change __dax_pmd_fault() to split the PMD map, if present, before
returning with VM_FAULT_FALLBACK.
Signed-off-by: Toshi Kani <toshi.kani@hpe.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Matthew Wilcox <willy@linux.intel.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to '')
| -rw-r--r-- | fs/dax.c | 4 |
1 files changed, 3 insertions, 1 deletions
@@ -578,8 +578,10 @@ int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address, return VM_FAULT_FALLBACK; /* Fall back to PTEs if we're going to COW */ - if (write && !(vma->vm_flags & VM_SHARED)) + if (write && !(vma->vm_flags & VM_SHARED)) { + split_huge_pmd(vma, pmd, address); return VM_FAULT_FALLBACK; + } /* If the PMD would extend outside the VMA */ if (pmd_addr < vma->vm_start) return VM_FAULT_FALLBACK; |