diff options
| author | Ross Zwisler <ross.zwisler@linux.intel.com> | 2015-10-01 15:36:59 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2015-10-01 21:42:35 -0400 |
| commit | 8346c416d17bf5b4ea1508662959bb62e73fd6a5 (patch) | |
| tree | 059bcaf04ab8cce9fdc5b3d6698044da7ade9de8 | |
| parent | 2f84a8990ebbe235c59716896e017c6b2ca1200f (diff) | |
| download | linux-8346c416d17bf5b4ea1508662959bb62e73fd6a5.tar.gz | |
dax: fix NULL pointer in __dax_pmd_fault()
Commit 46c043ede471 ("mm: take i_mmap_lock in unmap_mapping_range() for
DAX") moved some code in __dax_pmd_fault() that was responsible for
zeroing newly allocated PMD pages. The new location didn't properly set
up 'kaddr', so when run this code resulted in a NULL pointer BUG.
Fix this by getting the correct 'kaddr' via bdev_direct_access().
Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Reported-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Matthew Wilcox <willy@linux.intel.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Dave Chinner <david@fromorbit.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | fs/dax.c | 13 |
1 files changed, 12 insertions, 1 deletions
diff --git a/fs/dax.c b/fs/dax.c index 7ae6df7ea1d2..bcfb14bfc1e4 100644 --- a/fs/dax.c +++ b/fs/dax.c @@ -569,8 +569,20 @@ int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address, if (!buffer_size_valid(&bh) || bh.b_size < PMD_SIZE) goto fallback; + sector = bh.b_blocknr << (blkbits - 9); + if (buffer_unwritten(&bh) || buffer_new(&bh)) { int i; + + length = bdev_direct_access(bh.b_bdev, sector, &kaddr, &pfn, + bh.b_size); + if (length < 0) { + result = VM_FAULT_SIGBUS; + goto out; + } + if ((length < PMD_SIZE) || (pfn & PG_PMD_COLOUR)) + goto fallback; + for (i = 0; i < PTRS_PER_PMD; i++) clear_pmem(kaddr + i * PAGE_SIZE, PAGE_SIZE); wmb_pmem(); @@ -623,7 +635,6 @@ int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address, result = VM_FAULT_NOPAGE; spin_unlock(ptl); } else { - sector = bh.b_blocknr << (blkbits - 9); length = bdev_direct_access(bh.b_bdev, sector, &kaddr, &pfn, bh.b_size); if (length < 0) { |