From: Shakeel Butt <shakeelb@xxxxxxxxxx> Subject: 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@xxxxxxxxxx Signed-off-by: Shakeel Butt <shakeelb@xxxxxxxxxx> Reviewed-by: Roman Gushchin <guro@xxxxxx> Cc: Roman Gushchin <roman.gushchin@xxxxxxxxx> Cc: Chris Down <chris@xxxxxxxxxxxxxx> Cc: Johannes Weiner <hannes@xxxxxxxxxxx> Cc: Michal Hocko <mhocko@xxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- tools/testing/selftests/cgroup/cgroup_util.c | 15 ++ tools/testing/selftests/cgroup/cgroup_util.h | 1 tools/testing/selftests/cgroup/test_memcontrol.c | 78 +++++++++++++ 3 files changed, 91 insertions(+), 3 deletions(-) --- a/tools/testing/selftests/cgroup/cgroup_util.c~selftests-memcg-test-high-limit-for-single-entry-allocation +++ a/tools/testing/selftests/cgroup/cgroup_util.c @@ -583,7 +583,7 @@ int clone_into_cgroup_run_wait(const cha 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 *cgro 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 *cgro 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; --- a/tools/testing/selftests/cgroup/cgroup_util.h~selftests-memcg-test-high-limit-for-single-entry-allocation +++ a/tools/testing/selftests/cgroup/cgroup_util.h @@ -55,4 +55,5 @@ extern int clone_reap(pid_t pid, int opt 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); --- a/tools/testing/selftests/cgroup/test_memcontrol.c~selftests-memcg-test-high-limit-for-single-entry-allocation +++ a/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), _
