fix undefined reference to user_shm_unlock

My 353d5c30c666580347515da609dd74a2b8e9b828 "mm: fix hugetlb bug due to
user_shm_unlock call" broke the CONFIG_SYSVIPC !CONFIG_MMU build of both
2.6.31 and 2.6.30.6: "undefined reference to `user_shm_unlock'".

gcc didn't understand my comment! so couldn't figure out to optimize
away user_shm_unlock() from the error path in the hugetlb-less case, as
it does elsewhere.  Help it to do so, in a language it understands.

Reported-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Hugh Dickins <hugh.dickins@tiscali.co.uk>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/ipc/shm.c b/ipc/shm.c
index 1bc4701..30162a5 100644 (file)
--- a/ipc/shm.c
+++ b/ipc/shm.c
@@ -410,7 +410,7 @@ static int newseg(struct ipc_namespace *ns, struct ipc_params *params)
        return error;
 
 no_id:
-       if (shp->mlock_user)    /* shmflg & SHM_HUGETLB case */
+       if (is_file_hugepages(file) && shp->mlock_user)
                user_shm_unlock(size, shp->mlock_user);
        fput(file);
 no_file: