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futex: Fix futex lock the wrong page

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The upstram commit 65d8fc777f ("futex: Remove requirement
for lock_page() in get_futex_key()") use variable 'page' as
the page head, when merge it to stable branch, the variable
`page_head` is page head.

In the stable branch, the variable `page` not means the page
head, when lock the page head, we should lock 'page_head',
rather than 'page'.

It maybe lead a hung task problem.

Signed-off-by: ZhangXiaoxu <zhangxiaoxu5@huawei.com>
Cc: stable@vger.kernel.org
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
ZhangXiaoxu
2019-06-12 09:54:25 +08:00
committed by Greg Kroah-Hartman
parent 38fbd5c2d5
commit cd23996afa
1 changed files with 2 additions and 2 deletions
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4
kernel/futex.c
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@@ -593,8 +593,8 @@ again:
* applies. If this is really a shmem page then the page lock
* will prevent unexpected transitions.
*/
lock_page(page);
shmem_swizzled = PageSwapCache(page) || page->mapping;
lock_page(page_head);
shmem_swizzled = PageSwapCache(page_head) || page_head->mapping;
unlock_page(page_head);
put_page(page_head);