From a7f1d48585b34730765dcda09ead6edc4ac16a5c Mon Sep 17 00:00:00 2001
From: Vlastimil Babka <vbabka@suse.cz>
Date: Fri, 13 Aug 2021 16:54:34 -0700
Subject: [PATCH] mm: slub: fix slub_debug disabling for list of slabs
Vijayanand Jitta reports:
Consider the scenario where CONFIG_SLUB_DEBUG_ON is set and we would
want to disable slub_debug for few slabs. Using boot parameter with
slub_debug=-,slab_name syntax doesn't work as expected i.e; only
disabling debugging for the specified list of slabs. Instead it
disables debugging for all slabs, which is wrong.
This patch fixes it by delaying the moment when the global slub_debug
flags variable is updated. In case a "slub_debug=-,slab_name" has been
passed, the global flags remain as initialized (depending on
CONFIG_SLUB_DEBUG_ON enabled or disabled) and are not simply reset to 0.
Link: https://lkml.kernel.org/r/8a3d992a-473a-467b-28a0-4ad2ff60ab82@suse.cz
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Reported-by: Vijayanand Jitta <vjitta@codeaurora.org>
Reviewed-by: Vijayanand Jitta <vjitta@codeaurora.org>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Vinayak Menon <vinmenon@codeaurora.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
mm/slub.c | 13 ++++++++-----
1 file changed, 8 insertions(+), 5 deletions(-)
diff --git a/mm/slub.c b/mm/slub.c
index 5c2a13d66e719..f77d8cd79ef7f 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -1400,12 +1400,13 @@ parse_slub_debug_flags(char *str, slab_flags_t *flags, char **slabs, bool init)
static int __init setup_slub_debug(char *str)
{
slab_flags_t flags;
+ slab_flags_t global_flags;
char *saved_str;
char *slab_list;
bool global_slub_debug_changed = false;
bool slab_list_specified = false;
- slub_debug = DEBUG_DEFAULT_FLAGS;
+ global_flags = DEBUG_DEFAULT_FLAGS;
if (*str++ != '=' || !*str)
/*
* No options specified. Switch on full debugging.
@@ -1417,7 +1418,7 @@ static int __init setup_slub_debug(char *str)
str = parse_slub_debug_flags(str, &flags, &slab_list, true);
if (!slab_list) {
- slub_debug = flags;
+ global_flags = flags;
global_slub_debug_changed = true;
} else {
slab_list_specified = true;
@@ -1426,16 +1427,18 @@ static int __init setup_slub_debug(char *str)
/*
* For backwards compatibility, a single list of flags with list of
- * slabs means debugging is only enabled for those slabs, so the global
- * slub_debug should be 0. We can extended that to multiple lists as
+ * slabs means debugging is only changed for those slabs, so the global
+ * slub_debug should be unchanged (0 or DEBUG_DEFAULT_FLAGS, depending
+ * on CONFIG_SLUB_DEBUG_ON). We can extended that to multiple lists as
* long as there is no option specifying flags without a slab list.
*/
if (slab_list_specified) {
if (!global_slub_debug_changed)
- slub_debug = 0;
+ global_flags = slub_debug;
slub_debug_string = saved_str;
}
out:
+ slub_debug = global_flags;
if (slub_debug != 0 || slub_debug_string)
static_branch_enable(&slub_debug_enabled);
else
--
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