diff options
| author | Arnd Bergmann <arnd@arndb.de> | 2012-01-09 16:14:07 +0000 |
|---|---|---|
| committer | Arnd Bergmann <arnd@arndb.de> | 2012-01-09 16:14:07 +0000 |
| commit | 142f2101a86ade2d6c9dfbedf82e1b5b31c8fce6 (patch) | |
| tree | 8cced517382b7087df4e89a9e2a00ccac9676a92 /kernel/futex.c | |
| parent | 155bc27fdfbdf65a07a4f8ef3eafa25e57d8b511 (diff) | |
| parent | a07613a54d700a974f3a4a657da78ef5d097315d (diff) | |
| download | linux-142f2101a86ade2d6c9dfbedf82e1b5b31c8fce6.tar.bz2 | |
Merge branch 'samsung/cleanup' into samsung/driver
Conflicts:
arch/arm/mach-s5p64x0/cpu.c -> common.c
More changes to a file that got moved into common.c,
see previous conflict resolutions.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Diffstat (limited to 'kernel/futex.c')
| -rw-r--r-- | kernel/futex.c | 28 |
1 files changed, 20 insertions, 8 deletions
diff --git a/kernel/futex.c b/kernel/futex.c index ea87f4d2f455..1614be20173d 100644 --- a/kernel/futex.c +++ b/kernel/futex.c @@ -314,17 +314,29 @@ again: #endif lock_page(page_head); + + /* + * If page_head->mapping is NULL, then it cannot be a PageAnon + * page; but it might be the ZERO_PAGE or in the gate area or + * in a special mapping (all cases which we are happy to fail); + * or it may have been a good file page when get_user_pages_fast + * found it, but truncated or holepunched or subjected to + * invalidate_complete_page2 before we got the page lock (also + * cases which we are happy to fail). And we hold a reference, + * so refcount care in invalidate_complete_page's remove_mapping + * prevents drop_caches from setting mapping to NULL beneath us. + * + * The case we do have to guard against is when memory pressure made + * shmem_writepage move it from filecache to swapcache beneath us: + * an unlikely race, but we do need to retry for page_head->mapping. + */ if (!page_head->mapping) { + int shmem_swizzled = PageSwapCache(page_head); unlock_page(page_head); put_page(page_head); - /* - * ZERO_PAGE pages don't have a mapping. Avoid a busy loop - * trying to find one. RW mapping would have COW'd (and thus - * have a mapping) so this page is RO and won't ever change. - */ - if ((page_head == ZERO_PAGE(address))) - return -EFAULT; - goto again; + if (shmem_swizzled) + goto again; + return -EFAULT; } /* |