[040/227] mm/memcontrol: return 1 from cgroup.memory __setup() handler

Commit Message

Andrew Morton March 22, 2022, 9:40 p.m. UTC

From: Randy Dunlap <[e-mail]>
Subject: mm/memcontrol: return 1 from cgroup.memory __setup() handler

__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/[e-mail]
Fixes: f7e1cb6ec51b0 ("mm: memcontrol: account socket memory in unified hierarchy memory controller")
Signed-off-by: Randy Dunlap <[e-mail]>
Reported-by: Igor Zhbanov <[e-mail]>
Link: lore.kernel.org/r/[e-mail]
Reviewed-by: Michal Koutný <[e-mail]>
Cc: Johannes Weiner <[e-mail]>
Cc: Michal Hocko <[e-mail]>
Cc: Vladimir Davydov <[e-mail]>
Cc: Roman Gushchin <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
---

 mm/memcontrol.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Patch

--- a/mm/memcontrol.c~mm-memcontrol-return-1-from-cgroupmemory-__setup-handler
+++ a/mm/memcontrol.c
@@ -7058,7 +7058,7 @@  static int __init cgroup_memory(char *s)
 		if (!strcmp(token, "nokmem"))
 			cgroup_memory_nokmem = true;
 	}
-	return 0;
+	return 1;
 }
 __setup("cgroup.memory=", cgroup_memory);