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author | Ingo Molnar <mingo@kernel.org> | 2016-06-14 09:17:42 (GMT) |
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committer | Ingo Molnar <mingo@kernel.org> | 2016-06-14 09:17:42 (GMT) |
commit | 245050c287a9176cee9f98109df101909c1eeef4 (patch) | |
tree | 77358451bcc85e3fa2ab824240d5b351894ce74c /kernel/futex.c | |
parent | d4c3be70ca0e7a1ae308bedd3462900c61e97b11 (diff) | |
parent | db06d759d6cf903aeda8c107fd3abd366dd80200 (diff) | |
download | linux-245050c287a9176cee9f98109df101909c1eeef4.tar.xz |
Merge branch 'linus' into locking/core, to pick up fixes before merging new changes
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/futex.c')
-rw-r--r-- | kernel/futex.c | 14 |
1 files changed, 11 insertions, 3 deletions
diff --git a/kernel/futex.c b/kernel/futex.c index ee25f5b..33664f7 100644 --- a/kernel/futex.c +++ b/kernel/futex.c @@ -469,7 +469,7 @@ get_futex_key(u32 __user *uaddr, int fshared, union futex_key *key, int rw) { unsigned long address = (unsigned long)uaddr; struct mm_struct *mm = current->mm; - struct page *page; + struct page *page, *tail; struct address_space *mapping; int err, ro = 0; @@ -530,7 +530,15 @@ again: * considered here and page lock forces unnecessarily serialization * From this point on, mapping will be re-verified if necessary and * page lock will be acquired only if it is unavoidable - */ + * + * Mapping checks require the head page for any compound page so the + * head page and mapping is looked up now. For anonymous pages, it + * does not matter if the page splits in the future as the key is + * based on the address. For filesystem-backed pages, the tail is + * required as the index of the page determines the key. For + * base pages, there is no tail page and tail == page. + */ + tail = page; page = compound_head(page); mapping = READ_ONCE(page->mapping); @@ -654,7 +662,7 @@ again: key->both.offset |= FUT_OFF_INODE; /* inode-based key */ key->shared.inode = inode; - key->shared.pgoff = basepage_index(page); + key->shared.pgoff = basepage_index(tail); rcu_read_unlock(); } |