linux-kernel - [PATCH 5.10 578/599] mm/memcontrol: return 1 from cgroup.memory _

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Date:   Tue,  5 Apr 2022 09:34:32 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Randy Dunlap <rdunlap@...radead.org>,
        Igor Zhbanov <i.zhbanov@...russia.ru>,
        Michal Koutný <mkoutny@...e.com>,
        Johannes Weiner <hannes@...xchg.org>,
        Michal Hocko <mhocko@...nel.org>,
        Vladimir Davydov <vdavydov.dev@...il.com>,
        Roman Gushchin <roman.gushchin@...ux.dev>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>
Subject: [PATCH 5.10 578/599] mm/memcontrol: return 1 from cgroup.memory __setup() handler

From: Randy Dunlap <rdunlap@...radead.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@...radead.org>
Reported-by: Igor Zhbanov <i.zhbanov@...russia.ru>
Link: lore.kernel.org/r/64644a2f-4a20-bab3-1e15-3b2cdd0defe3@...russia.ru
Reviewed-by: Michal Koutný <mkoutny@...e.com>
Cc: Johannes Weiner <hannes@...xchg.org>
Cc: Michal Hocko <mhocko@...nel.org>
Cc: Vladimir Davydov <vdavydov.dev@...il.com>
Cc: Roman Gushchin <roman.gushchin@...ux.dev>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 mm/memcontrol.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -7124,7 +7124,7 @@ static int __init cgroup_memory(char *s)
 		if (!strcmp(token, "nokmem"))
 			cgroup_memory_nokmem = true;
 	}
-	return 0;
+	return 1;
 }
 __setup("cgroup.memory=", cgroup_memory);