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author | Kirill A. Shutemov <kirill.shutemov@linux.intel.com> | 2016-02-12 03:13:03 +0300 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2016-02-12 05:35:48 +0300 |
commit | 6b9116a652bd9e0e2994505cfaaa5f66deaa2a05 (patch) | |
tree | 9e9ae34807081abbec6ed856f4ed7c1f9b33d225 /init | |
parent | 7eb391299419a03cbe0fa5ab0e6b0932e42c7a36 (diff) | |
download | linux-6b9116a652bd9e0e2994505cfaaa5f66deaa2a05.tar.xz |
mm, dax: check for pmd_none() after split_huge_pmd()
DAX implements split_huge_pmd() by clearing pmd. This simple approach
reduces memory overhead, as we don't need to deposit page table on huge
page mapping to make split_huge_pmd() never-fail. PTE table can be
allocated and populated later on page fault from backing store.
But one side effect is that have to check if pmd is pmd_none() after
split_huge_pmd(). In most places we do this already to deal with
parallel MADV_DONTNEED.
But I found two call sites which is not affected by MADV_DONTNEED (due
down_write(mmap_sem)), but need to have the check to work with DAX
properly.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Matthew Wilcox <willy@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.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 'init')
0 files changed, 0 insertions, 0 deletions