[PATCH 4.14 196/284] mm/memcontrol: return 1 from cgroup.memory __setup() handler

Greg Kroah-Hartman
2022-04-18T13:54:34Z

From: Randy Dunlap <rdunlap@infradead.org>

commit 460a79e18842caca6fa0c415de4a3ac1e671ac50 upstream.

__setup() handlers should return 1 if the command line option is handled
and 0 if not (or maybe never return 0; it just pollutes init's
environment).

The only reason that this particular __setup handler does not pollute
init's environment is that the setup string contains a '.', as in
"cgroup.memory". This causes init/main.c::unknown_boottoption() to
consider it to be an "Unused module parameter" and ignore it. (This is
for parsing of loadable module parameters any time after kernel init.)
Otherwise the string "cgroup.memory=whatever" would be added to init's
environment strings.

Instead of relying on this '.' quirk, just return 1 to indicate that the
boot option has been handled.

Note that there is no warning message if someone enters:
cgroup.memory=anything_invalid

Link: https://lkml.kernel.org/r/20220222005811.10672-1-rdunlap@infradead.org
Fixes: f7e1cb6ec51b0 ("mm: memcontrol: account socket memory in unified hierarchy memory controller")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Reported-by: Igor Zhbanov <i.zhbanov@omprussia.ru>
Link: lore.kernel.org/r/64644a2f-4a20-bab3-1e15-3b2cdd0defe3@omprussia.ru
Reviewed-by: Michal Koutný <mkoutny@suse.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
mm/memcontrol.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -5978,7 +5978,7 @@ static int __init cgroup_memory(char *s)
if (!strcmp(token, "nokmem"))
cgroup_memory_nokmem = true;
}
- return 0;
+ return 1;
}
__setup("cgroup.memory=", cgroup_memory);