On Sun, 21 Mar 2021 21:25:01 +0000
Sergei Trofimovich <sly...@gentoo.org> wrote:
> On some architectures (like ia64) stack walking is slow
> and currently requires memory allocation. This causes stack
> collection for page_owner=on to fall into recursion.
>
> This patch implements a page_owner_stack=off to allow page stats
> collection.
More user friendly alternative would be to have a GFP_ flag similar
to __GFP_NOLOCKDEP which would allow us to skip the recursion.
I'll prepare alternative patch.
> Signed-off-by: Sergei Trofimovich <sly...@gentoo.org>
> ---
> .../admin-guide/kernel-parameters.txt | 6 +++++
> mm/Kconfig.debug | 3 ++-
> mm/page_owner.c | 23 +++++++++++++------
> 3 files changed, 24 insertions(+), 8 deletions(-)
>
> diff --git a/Documentation/admin-guide/kernel-parameters.txt
> b/Documentation/admin-guide/kernel-parameters.txt
> index 04545725f187..3e710c4ab4df 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -3518,6 +3518,12 @@
> we can turn it on.
> on: enable the feature
>
> + page_owner_stack= [KNL] Boot-time parameter option disabling stack
> + collection of page allocation. Has effect only if
> + "page_owner=on" is set. Useful for cases when stack
> + collection is too slow or not feasible.
> + off: disable the feature
> +
> page_poison= [KNL] Boot-time parameter changing the state of
> poisoning on the buddy allocator, available with
> CONFIG_PAGE_POISONING=y.
> diff --git a/mm/Kconfig.debug b/mm/Kconfig.debug
> index 1e73717802f8..c1ecaf066c93 100644
> --- a/mm/Kconfig.debug
> +++ b/mm/Kconfig.debug
> @@ -57,7 +57,8 @@ config PAGE_OWNER
> help to find bare alloc_page(s) leaks. Even if you include this
> feature on your build, it is disabled in default. You should pass
> "page_owner=on" to boot parameter in order to enable it. Eats
> - a fair amount of memory if enabled. See tools/vm/page_owner_sort.c
> + a fair amount of memory if enabled. Call chain tracking can be
> + disabled with "page_owner_stack=off". See tools/vm/page_owner_sort.c
> for user-space helper.
>
> If unsure, say N.
> diff --git a/mm/page_owner.c b/mm/page_owner.c
> index d15c7c4994f5..2cc1113fa28d 100644
> --- a/mm/page_owner.c
> +++ b/mm/page_owner.c
> @@ -31,6 +31,7 @@ struct page_owner {
> };
>
> static bool page_owner_enabled = false;
> +static bool page_owner_stack_enabled = true;
> DEFINE_STATIC_KEY_FALSE(page_owner_inited);
>
> static depot_stack_handle_t dummy_handle;
> @@ -41,21 +42,26 @@ static void init_early_allocated_pages(void);
>
> static int __init early_page_owner_param(char *buf)
> {
> - if (!buf)
> - return -EINVAL;
> -
> - if (strcmp(buf, "on") == 0)
> - page_owner_enabled = true;
> -
> - return 0;
> + return kstrtobool(buf, &page_owner_enabled);
> }
> early_param("page_owner", early_page_owner_param);
>
> +static int __init early_page_owner_stack_param(char *buf)
> +{
> + return kstrtobool(buf, &page_owner_stack_enabled);
> +}
> +early_param("page_owner_stack", early_page_owner_stack_param);
> +
> static bool need_page_owner(void)
> {
> return page_owner_enabled;
> }
>
> +static bool need_page_owner_stack(void)
> +{
> + return page_owner_stack_enabled;
> +}
> +
> static __always_inline depot_stack_handle_t create_dummy_stack(void)
> {
> unsigned long entries[4];
> @@ -122,6 +128,9 @@ static noinline depot_stack_handle_t save_stack(gfp_t
> flags)
> depot_stack_handle_t handle;
> unsigned int nr_entries;
>
> + if (!need_page_owner_stack())
> + return failure_handle;
> +
> nr_entries = stack_trace_save(entries, ARRAY_SIZE(entries), 2);
>
> /*
> --
> 2.31.0
>
--
Sergei
