Hi,
just typos etc.
On 3/11/24 09:46, Pasha Tatashin wrote:
> The core implementation of dynamic kernel stacks.
>
...
>
> Signed-off-by: Pasha Tatashin <pasha.tatashin@xxxxxxxxxx>
> ---
> arch/Kconfig | 34 +++++
> include/linux/sched.h | 2 +-
> include/linux/sched/task_stack.h | 41 +++++-
> kernel/fork.c | 239 +++++++++++++++++++++++++++++++
> kernel/sched/core.c | 1 +
> 5 files changed, 315 insertions(+), 2 deletions(-)
>
> diff --git a/arch/Kconfig b/arch/Kconfig
> index a5af0edd3eb8..da3df347b069 100644
> --- a/arch/Kconfig
> +++ b/arch/Kconfig
> @@ -1241,6 +1241,40 @@ config VMAP_STACK
> backing virtual mappings with real shadow memory, and KASAN_VMALLOC
> must be enabled.
>
> +config HAVE_ARCH_DYNAMIC_STACK
> + def_bool n
> + help
> + An arch should select this symbol if it can support kernel stacks
> + dynamic growth.
> +
> + - Arch must have support for HAVE_ARCH_VMAP_STACK, in order to handle
> + stack related page faults
stack-related
> +
> + - Arch must be able to faults from interrupt context.
fault
> + - Arch must allows the kernel to handle stack faults gracefully, even
allow
> + during interrupt handling.
> +
> + - Exceptions such as no pages available should be handled the same
handled in the same
> + in the consitent and predictable way. I.e. the exception should be
consistent
> + handled the same as when stack overflow occurs when guard pages are
> + touched with extra information about the allocation error.
> +
> +config DYNAMIC_STACK
> + default y
> + bool "Dynamically grow kernel stacks"
> + depends on THREAD_INFO_IN_TASK
> + depends on HAVE_ARCH_DYNAMIC_STACK
> + depends on VMAP_STACK
> + depends on !KASAN
> + depends on !DEBUG_STACK_USAGE
> + depends on !STACK_GROWSUP
> + help
> + Dynamic kernel stacks allow to save memory on machines with a lot of
> + threads by starting with small stacks, and grow them only when needed.
> + On workloads where most of the stack depth do not reach over one page
does
> + the memory saving can be subsentantial. The feature requires virtually
substantial.
> + mapped kernel stacks in order to handle page faults.
> +
> config HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
> def_bool n
> help
> +/*
> + * This flag is used to pass information from fault handler to refill about
> + * which pages were allocated, and should be charged to memcg.
> + */
> +#define DYNAMIC_STACK_PAGE_AQUIRED_FLAG 0x1
ACQUIRED
please
--
#Randy
