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author | Otavio Salvador <otavio@ossystems.com.br> | 2019-12-19 00:14:33 -0300 |
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committer | GitHub <noreply@github.com> | 2019-12-19 00:14:33 -0300 |
commit | fa8a03bec68d9ef89da72277bd3501ed3daa6217 (patch) | |
tree | 3d3218332bcb34cb0afa01d6ad996058a3dbcb77 /include/linux/page-flags.h | |
parent | 6b774eec1f9d3064e9b33634dfa99d5666d0a73a (diff) | |
parent | 1ddf624b0b268fdc0b80b1de618b98f8d117afea (diff) |
Merge pull request #55 from toradex/4.14-2.0.x-imx
4.14 2.0.x imx
Diffstat (limited to 'include/linux/page-flags.h')
-rw-r--r-- | include/linux/page-flags.h | 20 |
1 files changed, 18 insertions, 2 deletions
diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h index 584b14c774c1..5f966c94732b 100644 --- a/include/linux/page-flags.h +++ b/include/linux/page-flags.h @@ -565,12 +565,28 @@ static inline int PageTransCompound(struct page *page) * * Unlike PageTransCompound, this is safe to be called only while * split_huge_pmd() cannot run from under us, like if protected by the - * MMU notifier, otherwise it may result in page->_mapcount < 0 false + * MMU notifier, otherwise it may result in page->_mapcount check false * positives. + * + * We have to treat page cache THP differently since every subpage of it + * would get _mapcount inc'ed once it is PMD mapped. But, it may be PTE + * mapped in the current process so comparing subpage's _mapcount to + * compound_mapcount to filter out PTE mapped case. */ static inline int PageTransCompoundMap(struct page *page) { - return PageTransCompound(page) && atomic_read(&page->_mapcount) < 0; + struct page *head; + + if (!PageTransCompound(page)) + return 0; + + if (PageAnon(page)) + return atomic_read(&page->_mapcount) < 0; + + head = compound_head(page); + /* File THP is PMD mapped and not PTE mapped */ + return atomic_read(&page->_mapcount) == + atomic_read(compound_mapcount_ptr(head)); } /* |