Re: [PATCH bpf v2 1/2] bpf: Add sleepable arena page allocation path

["Emil Tsalapatis" <emil@etsalapatis.com>]

On Thu Sep 24, 2026 at 9:33 PM UTC, Alexei Starovoitov wrote:
> On Thu, Sep 24, 2026 at 05:36 AM Emil Tsalapatis <emil@etsalapatis.com> wrote:
>> Add a separate arena page allocation path just for sleepable callers.
>> The path preallocates the arena memory to be added to the tree before
>> taking the critical section.
>
> Another idea...
> can we drop pages[] and link the pages via page->pcp_llist
> the way apply_range_clear_cb() does on the free side ?
>
> Then both sleepable and non-sleepable allocate all pages before
> taking the lock and there is no need for kvcalloc vs kmalloc_nolock,
> batching, etc.
> The whole function will probably be much simpler.

That would be ideal. Most of the complexity of this has been shaping the
function around the fact we need these intermediate arrays that force us
to drop the lock to refill/possibly require significant memory allocations.
pcp_llist should be available to use after allocating the page. I'll adjust
and resend.

>
> pw-bot: cr