Re: [PATCH v3] mm/memory: drop PROCESS_PAGES_NON_PREEMPT_BATCH

[David Hildenbrand (Arm)]

On 11/9/26 20:15, Shivank Garg wrote:
> clear_contig_highpages() clears the whole range at once under
> preemptible models. Otherwise it clears PROCESS_PAGES_NON_PREEMPT_BATCH
> pages at a time, with a cond_resched() in between. The batch is 32MB if
> the architecture defines clear_pages(), and one page otherwise.
> 
> Since commit 7dadeaa6e851 ("sched: Further restrict the preemption
> modes"), architectures that support lazy preemption only offer the
> full, lazy and RT preemption models, also with PREEMPT_DYNAMIC. x86 is
> one of them, and it is the only architecture that defines
> clear_pages(). So the 32MB batch is never used: whenever
> clear_contig_highpages() runs under a cooperative model, the batch is
> one page.
> 
> Make that explicit. Clear the whole range when CONFIG_PREEMPTION is
> set, and one page at a time with cond_resched() in between otherwise.
> Drop PROCESS_PAGES_NON_PREEMPT_BATCH, which has no other users.
> 
> PREEMPT_DYNAMIC kernels also have CONFIG_PREEMPTION set, and
> cond_resched() does nothing on any of these kernels. So a build-time
> CONFIG_PREEMPTION check is enough, and preempt_model_preemptible() is
> not needed.
> 
> No functional change intended.
> 
> Suggested-by: David Hildenbrand <david@xxxxxxxxxx>
> Reviewed-by: Pedro Falcato <pfalcato@xxxxxxx>
> Signed-off-by: Shivank Garg <shivankg@xxxxxxx>
> ---
>

Thanks, I'll wait a bit for more review before applying.

Reviewed-by: David Hildenbrand (Arm) <david@xxxxxxxxxx>

-- 
Cheers,

David