selftests: memcg: test high limit for single entry allocation

Test the enforcement of memory.high limit for large amount of memory
allocation within a single kernel entry.  There are valid use-cases
where the application can trigger large amount of memory allocation
within a single syscall e.g.  mlock() or mmap(MAP_POPULATE).

Make sure memory.high limit enforcement works for such use-cases.

Link: https://lkml.kernel.org/r/20220211064917.2028469-4-shakeelb@google.com
Signed-off-by: Shakeel Butt <shakeelb@google.com>
Reviewed-by: Roman Gushchin <guro@fb.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Chris Down <chris@chrisdown.name>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/tools/testing/selftests/cgroup/cgroup_util.c b/tools/testing/selftests/cgroup/cgroup_util.c
index 0cf7e90..dbaa7aa 100644 (file)
--- a/tools/testing/selftests/cgroup/cgroup_util.c
+++ b/tools/testing/selftests/cgroup/cgroup_util.c
@@ -583,7 +583,7 @@ int clone_into_cgroup_run_wait(const char *cgroup)
        return 0;
 }
 
-int cg_prepare_for_wait(const char *cgroup)
+static int __prepare_for_wait(const char *cgroup, const char *filename)
 {
        int fd, ret = -1;
 
@@ -591,8 +591,7 @@ int cg_prepare_for_wait(const char *cgroup)
        if (fd == -1)
                return fd;
 
-       ret = inotify_add_watch(fd, cg_control(cgroup, "cgroup.events"),
-                               IN_MODIFY);
+       ret = inotify_add_watch(fd, cg_control(cgroup, filename), IN_MODIFY);
        if (ret == -1) {
                close(fd);
                fd = -1;
@@ -601,6 +600,16 @@ int cg_prepare_for_wait(const char *cgroup)
        return fd;
 }
 
+int cg_prepare_for_wait(const char *cgroup)
+{
+       return __prepare_for_wait(cgroup, "cgroup.events");
+}
+
+int memcg_prepare_for_wait(const char *cgroup)
+{
+       return __prepare_for_wait(cgroup, "memory.events");
+}
+
 int cg_wait_for(int fd)
 {
        int ret = -1;

diff --git a/tools/testing/selftests/cgroup/cgroup_util.h b/tools/testing/selftests/cgroup/cgroup_util.h
index 4f66d10..6287385 100644 (file)
--- a/tools/testing/selftests/cgroup/cgroup_util.h
+++ b/tools/testing/selftests/cgroup/cgroup_util.h
@@ -55,4 +55,5 @@ extern int clone_reap(pid_t pid, int options);
 extern int clone_into_cgroup_run_wait(const char *cgroup);
 extern int dirfd_open_opath(const char *dir);
 extern int cg_prepare_for_wait(const char *cgroup);
+extern int memcg_prepare_for_wait(const char *cgroup);
 extern int cg_wait_for(int fd);

diff --git a/tools/testing/selftests/cgroup/test_memcontrol.c b/tools/testing/selftests/cgroup/test_memcontrol.c
index c19a97d..36ccf23 100644 (file)
--- a/tools/testing/selftests/cgroup/test_memcontrol.c
+++ b/tools/testing/selftests/cgroup/test_memcontrol.c
@@ -16,6 +16,7 @@
 #include <netinet/in.h>
 #include <netdb.h>
 #include <errno.h>
+#include <sys/mman.h>
 
 #include "../kselftest.h"
 #include "cgroup_util.h"
@@ -628,6 +629,82 @@ cleanup:
        return ret;
 }
 
+static int alloc_anon_mlock(const char *cgroup, void *arg)
+{
+       size_t size = (size_t)arg;
+       void *buf;
+
+       buf = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANON,
+                  0, 0);
+       if (buf == MAP_FAILED)
+               return -1;
+
+       mlock(buf, size);
+       munmap(buf, size);
+       return 0;
+}
+
+/*
+ * This test checks that memory.high is able to throttle big single shot
+ * allocation i.e. large allocation within one kernel entry.
+ */
+static int test_memcg_high_sync(const char *root)
+{
+       int ret = KSFT_FAIL, pid, fd = -1;
+       char *memcg;
+       long pre_high, pre_max;
+       long post_high, post_max;
+
+       memcg = cg_name(root, "memcg_test");
+       if (!memcg)
+               goto cleanup;
+
+       if (cg_create(memcg))
+               goto cleanup;
+
+       pre_high = cg_read_key_long(memcg, "memory.events", "high ");
+       pre_max = cg_read_key_long(memcg, "memory.events", "max ");
+       if (pre_high < 0 || pre_max < 0)
+               goto cleanup;
+
+       if (cg_write(memcg, "memory.swap.max", "0"))
+               goto cleanup;
+
+       if (cg_write(memcg, "memory.high", "30M"))
+               goto cleanup;
+
+       if (cg_write(memcg, "memory.max", "140M"))
+               goto cleanup;
+
+       fd = memcg_prepare_for_wait(memcg);
+       if (fd < 0)
+               goto cleanup;
+
+       pid = cg_run_nowait(memcg, alloc_anon_mlock, (void *)MB(200));
+       if (pid < 0)
+               goto cleanup;
+
+       cg_wait_for(fd);
+
+       post_high = cg_read_key_long(memcg, "memory.events", "high ");
+       post_max = cg_read_key_long(memcg, "memory.events", "max ");
+       if (post_high < 0 || post_max < 0)
+               goto cleanup;
+
+       if (pre_high == post_high || pre_max != post_max)
+               goto cleanup;
+
+       ret = KSFT_PASS;
+
+cleanup:
+       if (fd >= 0)
+               close(fd);
+       cg_destroy(memcg);
+       free(memcg);
+
+       return ret;
+}
+
 /*
  * This test checks that memory.max limits the amount of
  * memory which can be consumed by either anonymous memory
@@ -1180,6 +1257,7 @@ struct memcg_test {
        T(test_memcg_min),
        T(test_memcg_low),
        T(test_memcg_high),
+       T(test_memcg_high_sync),
        T(test_memcg_max),
        T(test_memcg_oom_events),
        T(test_memcg_swap_max),