On Tue, Sep 22, 2026 at 04:35:37PM +0100, Lorenzo Stoakes (ARM) wrote:
>Commit 4a0100f7546f ("sparc64: use RCU page table freeing") enabled
>CONFIG_MMU_GATHER_RCU_TABLE_FREE for SMP sparc64 architectures, expressly
>for GUP-fast page table walkers.
>
>Naturally, UP systems do not have to worry about concurrent GUP fast
>operations.
>
>However, CONFIG_PREEMPT_RCU is also available even on a UP system, so a
>future pure-RCU page table walker requires MMU_GATHER_RCU_TABLE_FREE to be
>enabled on UP, even if concurrent GUP fast is not possible there.
>
>To enable future pure-RCU page table walkers, enable
>MMU_GATHER_RCU_TABLE_FREE unconditionally.
>
>With this change, it is no longer necessary to have !CONFIG_SMP
>pgtable_free_tlb(), so also remove this now dead code.
>
>This forms part of an overall effort to switch every architecture to this
>mode.
>
>Acked-by: Kiryl Shutsemau (Meta) <[email protected]>
>Signed-off-by: Lorenzo Stoakes (ARM) <[email protected]>
>---Also ran page-table teardown stress on qemu-system-sparc64 (sun4u, UP). That ran cleanly too ;) Feel free to add: Tested-by: Lance Yang <[email protected]> Acked-by: Lance Yang <[email protected]>
