Re: [PATCH v2 00/12] mm: make userland page table freeing RCU-safe

[Andrew Morton]

On Tue, 08 Sep 2026 13:32:09 +0100 "Lorenzo Stoakes (ARM)" <ljs@xxxxxxxxxx> wrote:

> The majority of architectures in the kernel defer page table freeing until
> an RCU grace period has elapsed, this series converts all remaining
> architectures to do so too and eliminates CONFIG_MMU_GATHER_RCU_TABLE_FREE
> altogether.
> 
> This is important because it enables safe lockless page table walking under
> RCU alone.
> 
> Doing so allows for reduced lock contention, avoids lock ordering concerns
> and enables fast, efficient and correct page table walking as a result.
> 
> Additionally it removes a bunch of code and architecture-specific behaviour
> which is always a beneficial thing to do.

Thanks.  It's early and unreviewed, but this is mainly an
if-it-compiles-its-good thing, so I'll add it for exposure to the
build/checker universe.

> However some arches required extra attention - sh-X2, m68k-motorola and
> sparc32.

OK.  Please lmk later if you think additional reviewer/tester attention
is desirable in these areas.