Re: [PATCH] x86/mm/32: Bring back vmalloc faulting on x86_32

[Andy Lutomirski]

On Wed, Sep 2, 2020 at 8:59 AM Joerg Roedel <joro@xxxxxxxxxx> wrote:
>
> From: Joerg Roedel <jroedel@xxxxxxx>
>
> One can not simply remove vmalloc faulting on x86-32. Upstream
>
>         commit: 7f0a002b5a21 ("x86/mm: remove vmalloc faulting")
>
> removed it on x86 alltogether because previously the
> arch_sync_kernel_mappings() interface was introduced. This interface
> added synchronization of vmalloc/ioremap page-table updates to all
> page-tables in the system at creation time and was thought to make
> vmalloc faulting obsolete.
>
> But that assumption was incredibly naive.

Does this mean we can get rid of arch_sync_kernel_mappings()?  Or
should we consider adding some locking to make it non-racy again?

-Andy