Re: [PATCH v5 6/8] mm: Introduce deferred freeing for kernel page tables

[Baolu Lu]

On 10/10/25 23:47, David Hildenbrand wrote:
> On 19.09.25 07:40, Lu Baolu wrote:
> > From: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
> >
> > This introduces a conditional asynchronous mechanism, enabled by
> > CONFIG_ASYNC_PGTABLE_FREE. When enabled, this mechanism defers the 
> > freeing
> > of pages that are used as page tables for kernel address mappings. These
> > pages are now queued to a work struct instead of being freed immediately.
>
> Okay, I now looked at patch #8 and I think the whole reason of this 
> patch is "batch-free page tables to minimize the impact of an expensive 
> cross-page table operation" which is a single TLB flush.
>
> > This deferred freeing provides a safe context for a future patch to add
>
> So I would claridy here instead something like
>
> "This deferred freeing allows for batch-freeing of page tables, 
> providing a safe context for performing a single expensive operation 
> (TLB flush) for a batch of kernel page tables instead of performing that 
> expensive operation for each page table."

The commit message has been updated, and CONFIG_ASYNC_PGTABLE_FREE has
been replaced with CONFIG_ASYNC_KERNEL_PGTABLE_FREE. Thank you for the
comments.

Thanks,
baolu