[RFC PATCH 00/15] io_uring: thread identity handoff for blocking inline issue

[Jens Axboe]

On 9/22/26 4:05 PM, Gabriel Krisman Bertazi wrote:
> Jens Axboe <axboe at kernel.dk> writes:
> 
>> On 9/11/26 11:33 AM, Gabriel Krisman Bertazi wrote:
>>> It has the downside of still requiring fixes to every path and we need
>>> to handle every new case that comes by, but it is much cleaner than
>>> plumbing a nonblock flag several layers down the stack across each
>>> subsystem or having subsystem-specific details in io_uring, which is
>>> what we have today.  On the upper side, it is much less complex than
>>> your approach. It also allow us to just back off during memory
>>> allocations that would block, solving the memory allocations anywhere in
>>> the submission path, not only inside ->issue(), which we discussed
>>> recently on discord.
>>
>> I think you'll find it'll be a lot MORE complicated than my approach!
>> Backing out error handling is going to be impossible in some cases,
>> think file systems for example. How would those cases be handled?
> 
> I understand there are many cases where it would be impossible, most, if
> not all of them, involving FS.  But I naively imagine we could back-off
> those early, before we get to the critical session, without even trying
> the nonblock approach, similar to what we do now, and punt to the io-wq,
> which is not going away anyway.  What I'd like to solve is drop the
> logic of other parts of the kernel that we need to keep in the io_uring
> layer, such as which network protocols will block and which won't.

The problem is that you don't always know until you're at the point of
no return. If it was that simple, we would not be talking about these
patches :-)

-- 
Jens Axboe