fork, memcg: fix cached_stacks case

BugLink: https://bugs.launchpad.net/bugs/1863019
[ Upstream commit ba4a45746c362b665e245c50b870615f02f34781 ]

Commit 5eed6f1dff87 ("fork,memcg: fix crash in free_thread_stack on
memcg charge fail") fixes a crash caused due to failed memcg charge of
the kernel stack.  However the fix misses the cached_stacks case which
this patch fixes.  So, the same crash can happen if the memcg charge of
a cached stack is failed.

Link: http://lkml.kernel.org/r/20190102180145.57406-1-shakeelb@google.com
Fixes: 5eed6f1dff87 ("fork,memcg: fix crash in free_thread_stack on memcg charge fail")
Signed-off-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Rik van Riel <riel@surriel.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

diff --git a/kernel/fork.c b/kernel/fork.c
index acbd476dce2cc04a2d3d308d531d40fb68f1f9c9..8358236909d724073cec2463b802fd7afe95e1bd 100644 (file)
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -220,6 +220,7 @@ static unsigned long *alloc_thread_stack_node(struct task_struct *tsk, int node)
                memset(s->addr, 0, THREAD_SIZE);
 
                tsk->stack_vm_area = s;
+               tsk->stack = s->addr;
                return s->addr;
        }