Re: [PATCH 1/2] io_uring: split alloc and add of overflow

[Jens Axboe <axboe@kernel.dk>]

On 5/16/25 10:43 AM, Pavel Begunkov wrote:
> On 5/16/25 17:08, Jens Axboe wrote:
>> Add a new helper, io_alloc_ocqe(), that simply allocates and fills an
>> overflow entry. Then it can get done outside of the locking section,
>> and hence use more appropriate gfp_t allocation flags rather than always
>> default to GFP_ATOMIC.
>>
>> Suggested-by: Pavel Begunkov <asml.silence@gmail.com>
> 
> I didn't suggest that. If anything, it complicates CQE posting
> helpers when we should be moving in the opposite direction.

I'll kill the attribution then - it's not meant to mean the
approach, but the concept of being able to use GFP_KERNEL
when we can.

>> @@ -1442,10 +1462,11 @@ void __io_submit_flush_completions(struct io_ring_ctx *ctx)
>>               unlikely(!io_fill_cqe_req(ctx, req))) {
>>               if (ctx->lockless_cq) {
>>                   spin_lock(&ctx->completion_lock);
>> -                io_req_cqe_overflow(req);
>> +                io_req_cqe_overflow(req, GFP_ATOMIC);
>>                   spin_unlock(&ctx->completion_lock);
>>               } else {
>> -                io_req_cqe_overflow(req);
>> +                gfp_t gfp = ctx->lockless_cq ? GFP_KERNEL : GFP_ATOMIC;
> 
> if (!ctx->lockless_cq)
>     gfp_t gfp = ctx->lockless_cq ? GFP_KERNEL : GFP_ATOMIC;
> 

Yeah see other reply to Caleb. I'll just slurp in your patch 1/4 as this
makes it simpler.

-- 
Jens Axboe