On Wed 31-07-19 09:45:53, Qian Cai wrote:
> The linux-next commit ("mm/memcontrol.c: fix use after free in
> mem_cgroup_iter()") [1] introduced a compilation warning,
>
> mm/memcontrol.c:1160:17: warning: using the result of an assignment as a
> condition without parentheses [-Wparentheses]
> } while (memcg = parent_mem_cgroup(memcg));
> ~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~
> mm/memcontrol.c:1160:17: note: place parentheses around the assignment
> to silence this warning
> } while (memcg = parent_mem_cgroup(memcg));
> ^
> ( )
> mm/memcontrol.c:1160:17: note: use '==' to turn this assignment into an
> equality comparison
> } while (memcg = parent_mem_cgroup(memcg));
> ^
> ==
>
> Fix it by adding a pair of parentheses.
>
> [1] https://lore.kernel.org/linux-mm/20190730015729.4406-1-miles.chen@xxxxxxxxxxxx/
>
> Signed-off-by: Qian Cai <cai@xxxxxx>
Thanks for the fix. I assume Andrew is going to squash it into the
original patch.
Acked-by: Michal Hocko <mhocko@xxxxxxxx>
> ---
> mm/memcontrol.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index 694b6f8776dc..4f66a8305ae0 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -1157,7 +1157,7 @@ static void invalidate_reclaim_iterators(struct mem_cgroup *dead_memcg)
> do {
> __invalidate_reclaim_iterators(memcg, dead_memcg);
> last = memcg;
> - } while (memcg = parent_mem_cgroup(memcg));
> + } while ((memcg = parent_mem_cgroup(memcg)));
>
> /*
> * When cgruop1 non-hierarchy mode is used,
> --
> 1.8.3.1
--
Michal Hocko
SUSE Labs
