[Devel] [PATCH RH7] mm/memcontrol: prohibit writing to memory.numa_migrate from container

[Pavel Tikhomirov]

We might want to put containers on designated numa nodes for optimal
perfomance, it will be all ruinied if container could force its memory
pages to move to any node it wants.

This memory.numa_migrate file was originaly made for vcmmd which works
from ve0, so we should be fine with this additional restriction.

Fixes: dfc0b63bfd50c ("mm: memcontrol: add memory.numa_migrate file")
https://virtuozzo.atlassian.net/browse/PSBM-152372
Signed-off-by: Pavel Tikhomirov <ptikhomirov at virtuozzo.com>

Feature: mm: interface to migrate memory between NUMA nodes upon userspace request
---
 mm/memcontrol.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index a2fe48d93d02a..5d65b523a0ec8 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -5812,8 +5812,8 @@ static int memcg_numa_migrate_pages(struct mem_cgroup *memcg,
  *
  * The call may be interrupted by a signal, in which case -EINTR is returned.
  */
-static int memcg_numa_migrate_write(struct cgroup *cont,
-		struct cftype *cft, const char *buf)
+static int __memcg_numa_migrate_write(struct cgroup *cont, struct cftype *cft,
+				      const char *buf)
 {
 	struct mem_cgroup *memcg = mem_cgroup_from_cont(cont);
 	NODEMASK_ALLOC(nodemask_t, target_nodes, GFP_KERNEL);
@@ -5851,6 +5851,14 @@ static int memcg_numa_migrate_write(struct cgroup *cont,
 	return ret;
 }
 
+static int memcg_numa_migrate_write(struct cgroup *cont, struct cftype *cft,
+				    const char *buf)
+	if (!ve_is_super(get_exec_env()))
+		return -EPERM;
+
+	return __memcg_numa_migrate_write(cont, cft, buf);
+}
+
 #endif /* CONFIG_NUMA */
 
 static inline void mem_cgroup_lru_names_not_uptodate(void)
-- 
2.43.0