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

On Wed, Sep 2, 2020 at 8:59 AM Joerg Roedel joro@8bytes.org wrote:

From: Joerg Roedel jroedel@suse.de

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