diff mbox series

[v5,3/4] selftests: cgroup: fix alloc_anon_noexit() instantly freeing memory

Message ID 20220425190040.2475377-4-yosryahmed@google.com
State Accepted
Commit a3622a53e620700053b648478dbc638ad373be3b
Headers show
Series memcg: introduce per-memcg proactive reclaim | expand

Commit Message

Yosry Ahmed April 25, 2022, 7 p.m. UTC 
Currently, alloc_anon_noexit() calls alloc_anon() which instantly frees
the allocated memory. alloc_anon_noexit() is usually used with
cg_run_nowait() to run a process in the background that allocates
memory. It makes sense for the background process to keep the memory
allocated and not instantly free it (otherwise there is no point of
running it in the background).

Signed-off-by: Yosry Ahmed <yosryahmed@google.com>
Acked-by: Roman Gushchin <roman.gushchin@linux.dev>
Acked-by: Shakeel Butt <shakeelb@google.com>
---
 tools/testing/selftests/cgroup/test_memcontrol.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

Comments

David Rientjes April 25, 2022, 7:18 p.m. UTC | #1 
On Mon, 25 Apr 2022, Yosry Ahmed wrote:

> Currently, alloc_anon_noexit() calls alloc_anon() which instantly frees
> the allocated memory. alloc_anon_noexit() is usually used with
> cg_run_nowait() to run a process in the background that allocates
> memory. It makes sense for the background process to keep the memory
> allocated and not instantly free it (otherwise there is no point of
> running it in the background).
> 
> Signed-off-by: Yosry Ahmed <yosryahmed@google.com>
> Acked-by: Roman Gushchin <roman.gushchin@linux.dev>
> Acked-by: Shakeel Butt <shakeelb@google.com>

Acked-by: David Rientjes <rientjes@google.com>
diff mbox series

Patch

diff --git a/tools/testing/selftests/cgroup/test_memcontrol.c b/tools/testing/selftests/cgroup/test_memcontrol.c
index 36ccf2322e21..f2ffb3a30194 100644
--- a/tools/testing/selftests/cgroup/test_memcontrol.c
+++ b/tools/testing/selftests/cgroup/test_memcontrol.c
@@ -211,13 +211,17 @@  static int alloc_pagecache_50M_noexit(const char *cgroup, void *arg)
 static int alloc_anon_noexit(const char *cgroup, void *arg)
 {
 	int ppid = getppid();
+	size_t size = (unsigned long)arg;
+	char *buf, *ptr;
 
-	if (alloc_anon(cgroup, arg))
-		return -1;
+	buf = malloc(size);
+	for (ptr = buf; ptr < buf + size; ptr += PAGE_SIZE)
+		*ptr = 0;
 
 	while (getppid() == ppid)
 		sleep(1);
 
+	free(buf);
 	return 0;
 }