On 27/10/2019 19:56, Jens Axboe wrote: > On 10/27/19 10:49 AM, Jens Axboe wrote: >> On 10/27/19 10:44 AM, Pavel Begunkov wrote: >>> On 27/10/2019 19:32, Jens Axboe wrote: >>>> On 10/27/19 9:35 AM, Pavel Begunkov wrote: >>>>> A small cleanup of very similar but diverged io_submit_sqes() and >>>>> io_ring_submit() >>>>> >>>>> Pavel Begunkov (2): >>>>> io_uring: handle mm_fault outside of submission >>>>> io_uring: merge io_submit_sqes and io_ring_submit >>>>> >>>>> fs/io_uring.c | 116 ++++++++++++++------------------------------------ >>>>> 1 file changed, 33 insertions(+), 83 deletions(-) >>>> >>>> I like the cleanups here, but one thing that seems off is the >>>> assumption that io_sq_thread() always needs to grab the mm. If >>>> the sqes processed are just READ/WRITE_FIXED, then it never needs >>>> to grab the mm. >>>> Yeah, we removed it to fix bugs. Personally, I think it would be >>> clearer to do lazy grabbing conditionally, rather than have two >>> functions. And in this case it's easier to do after merging. >>> >>> Do you prefer to return it back first? >> >> Ah I see, no I don't care about that. > > OK, looked at the post-patches state. It's still not correct. You are > grabbing the mm from io_sq_thread() unconditionally. We should not do > that, only if the sqes we need to submit need mm context. > That's what my question to the fix was about :) 1. Then, what the case it could fail? 2. Is it ok to hold it while polling? It could keep it for quite a long time if host is swift, e.g. submit->poll->submit->poll-> ... Anyway, I will add it back and resend the patchset. -- Yours sincerely, Pavel Begunkov
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