Re: [PATCH 1/1] mm: disable CONFIG_PER_VMA_LOCK by default until its fixed

[Hans de Goede <hdegoede@redhat.com>]

Hi Suren,

Thank you for your patch.

On 7/3/23 20:21, Suren Baghdasaryan wrote:
> A memory corruption was reported in [1] with bisection pointing to the
> patch [2] enabling per-VMA locks for x86.
> Disable per-VMA locks config to prevent this issue while the problem is
> being investigated. This is expected to be a temporary measure.
> 
> [1] https://bugzilla.kernel.org/show_bug.cgi?id=217624
> [2] https://lore.kernel.org/all/20230227173632.3292573-30-surenb@google.com
> 
> Reported-by: Jiri Slaby <jirislaby@kernel.org>
> Reported-by: Jacob Young <jacobly.alt@gmail.com>
> Fixes: 0bff0aaea03e ("x86/mm: try VMA lock-based page fault handling first")
> Signed-off-by: Suren Baghdasaryan <surenb@google.com>
> ---
>  mm/Kconfig | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/mm/Kconfig b/mm/Kconfig
> index 09130434e30d..de94b2497600 100644
> --- a/mm/Kconfig
> +++ b/mm/Kconfig
> @@ -1224,7 +1224,7 @@ config ARCH_SUPPORTS_PER_VMA_LOCK
>         def_bool n
>  
>  config PER_VMA_LOCK
> -	def_bool y
> +	bool "Enable per-vma locking during page fault handling."
>  	depends on ARCH_SUPPORTS_PER_VMA_LOCK && MMU && SMP
>  	help
>  	  Allow per-vma locking during page fault handling.


This does not disable the option it only makes it user selectable
and for users with an existing .config which already has this
it changes nothing.

IMHO you should add a "depends on BROKEN" here until this is fixed,
so that this really gets disabled.

Or maybe just revert 0bff0aaea03e2a3ed6bfa302155cca8a432a1829
for now?

Regards,

Hans