+ selftests-cgroup-fix-alloc_anon_noexit-instantly-freeing-memory.patch added to -mm tree

[Andrew Morton <akpm@linux-foundation.org>]

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The patch titled
     Subject: selftests: cgroup: fix alloc_anon_noexit() instantly freeing memory
has been added to the -mm tree.  Its filename is
     selftests-cgroup-fix-alloc_anon_noexit-instantly-freeing-memory.patch

This patch should soon appear at
    https://ozlabs.org/~akpm/mmots/broken-out/selftests-cgroup-fix-alloc_anon_noexit-instantly-freeing-memory.patch
and later at
    https://ozlabs.org/~akpm/mmotm/broken-out/selftests-cgroup-fix-alloc_anon_noexit-instantly-freeing-memory.patch

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------------------------------------------------------
From: Yosry Ahmed <yosryahmed@google.com>
Subject: selftests: cgroup: fix alloc_anon_noexit() instantly freeing memory

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).

Link: https://lkml.kernel.org/r/20220421234426.3494842-4-yosryahmed@google.com
Signed-off-by: Yosry Ahmed <yosryahmed@google.com>
Acked-by: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Chen Wandun <chenwandun@huawei.com>
Cc: Dan Schatzberg <schatzberg.dan@gmail.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Michal Hocko <mhocko@suse.com>
Cc: "Michal Koutný" <mkoutny@suse.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Vaibhav Jain <vaibhav@linux.ibm.com>
Cc: Wei Xu <weixugc@google.com>
Cc: Yu Zhao <yuzhao@google.com>
Cc: Zefan Li <lizefan.x@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 tools/testing/selftests/cgroup/test_memcontrol.c |    8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

--- a/tools/testing/selftests/cgroup/test_memcontrol.c~selftests-cgroup-fix-alloc_anon_noexit-instantly-freeing-memory
+++ a/tools/testing/selftests/cgroup/test_memcontrol.c
@@ -214,13 +214,17 @@ static int alloc_pagecache_50M_noexit(co
 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;
 }
 
_

Patches currently in -mm which might be from yosryahmed@google.com are

selftests-cgroup-return-errno-from-cg_read-cg_write-on-failure.patch
selftests-cgroup-fix-alloc_anon_noexit-instantly-freeing-memory.patch
selftests-cgroup-add-a-selftest-for-memoryreclaim.patch