From: Mateusz Nosek <mateusznosek0@xxxxxxxxx> Subject: mm/page_poison.c: replace bool variable with static key Variable 'want_page_poisoning' is a switch deciding if page poisoning should be enabled. This patch changes it to be static key. Link: https://lkml.kernel.org/r/20200921152931.938-1-mateusznosek0@xxxxxxxxx Signed-off-by: Mateusz Nosek <mateusznosek0@xxxxxxxxx> Cc: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx> Cc: Oscar Salvador <OSalvador@xxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/page_poison.c | 20 +++++++++++++++----- 1 file changed, 15 insertions(+), 5 deletions(-) --- a/mm/page_poison.c~mm-page_poisonc-replace-bool-variable-with-static-key +++ a/mm/page_poison.c @@ -8,13 +8,23 @@ #include <linux/ratelimit.h> #include <linux/kasan.h> -static bool want_page_poisoning __read_mostly; +static DEFINE_STATIC_KEY_FALSE_RO(want_page_poisoning); static int __init early_page_poison_param(char *buf) { - if (!buf) - return -EINVAL; - return strtobool(buf, &want_page_poisoning); + int ret; + bool tmp; + + ret = strtobool(buf, &tmp); + if (ret) + return ret; + + if (tmp) + static_branch_enable(&want_page_poisoning); + else + static_branch_disable(&want_page_poisoning); + + return 0; } early_param("page_poison", early_page_poison_param); @@ -31,7 +41,7 @@ bool page_poisoning_enabled(void) * Page poisoning is debug page alloc for some arches. If * either of those options are enabled, enable poisoning. */ - return (want_page_poisoning || + return (static_branch_unlikely(&want_page_poisoning) || (!IS_ENABLED(CONFIG_ARCH_SUPPORTS_DEBUG_PAGEALLOC) && debug_pagealloc_enabled())); } _
