From 19e5dc2e6bf7cb2160bbb996f18f3bfb4621e770 Mon Sep 17 00:00:00 2001
From: Johannes Weiner <hannes@cmpxchg.org>
Date: Tue, 13 Feb 2024 03:16:34 -0500
Subject: [PATCH] mm: memcontrol: clarify swapaccount=0 deprecation warning
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commit 118642d7f606fc9b9c92ee611275420320290ffb upstream.
The swapaccount deprecation warning is throwing false positives. Since we
deprecated the knob and defaulted to enabling, the only reports we've been
getting are from folks that set swapaccount=1. While this is a nice
affirmation that always-enabling was the right choice, we certainly don't
want to warn when users request the supported mode.
Only warn when disabling is requested, and clarify the warning.
[colin.i.king@gmail.com: spelling: "commdandline" -> "commandline"]
Link: https://lkml.kernel.org/r/20240215090544.1649201-1-colin.i.king@gmail.com
Link: https://lkml.kernel.org/r/20240213081634.3652326-1-hannes@cmpxchg.org
Fixes: b25806dcd3d5 ("mm: memcontrol: deprecate swapaccounting=0 mode")
Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
Reported-by: "Jonas Schäfer" <jonas@wielicki.name>
Reported-by: Narcis Garcia <debianlists@actiu.net>
Suggested-by: Yosry Ahmed <yosryahmed@google.com>
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Yosry Ahmed <yosryahmed@google.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Shakeel Butt <shakeelb@google.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
mm/memcontrol.c | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 9da98e3e71cf..4570d3e315cf 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -7517,9 +7517,13 @@ bool mem_cgroup_swap_full(struct folio *folio)
static int __init setup_swap_account(char *s)
{
- pr_warn_once("The swapaccount= commandline option is deprecated. "
- "Please report your usecase to linux-mm@kvack.org if you "
- "depend on this functionality.\n");
+ bool res;
+
+ if (!kstrtobool(s, &res) && !res)
+ pr_warn_once("The swapaccount=0 commandline option is deprecated "
+ "in favor of configuring swap control via cgroupfs. "
+ "Please report your usecase to linux-mm@kvack.org if you "
+ "depend on this functionality.\n");
return 1;
}
__setup("swapaccount=", setup_swap_account);