On 11/6/24 01:14, Pavel Begunkov wrote: > On 11/5/24 23:02, Bernd Schubert wrote: >> On 11/5/24 02:08, Pavel Begunkov wrote: >>> On 11/4/24 22:15, Bernd Schubert wrote: >>>> On 11/4/24 01:28, Pavel Begunkov wrote: >>> ... >>>>> In general if you need to change something, either stick your >>>>> name, so that I know it might be a derivative, or reflect it in >>>>> the commit message, e.g. >>>>> >>>>> Signed-off-by: initial author >>>>> [Person 2: changed this and that] >>>>> Signed-off-by: person 2 >>>> >>>> Oh sorry, for sure. I totally forgot to update the commit message. >>>> >>>> Somehow the initial version didn't trigger. I need to double check to >>> >>> "Didn't trigger" like in "kernel was still crashing"? >> >> My initial problem was a crash in iov_iter_get_pages2() on process >> kill. And when I tested your initial patch IO_URING_F_TASK_DEAD didn't >> get set. Jens then asked to test with the version that I have in my >> branch and that worked fine. Although in the mean time I wonder if >> I made test mistake (like just fuse.ko reload instead of reboot with >> new kernel). Just fixed a couple of issues in my branch (basically >> ready for the next version send), will test the initial patch >> again as first thing in the morning. > > I see. Please let know if it doesn't work, it's not specific > to fuse, if there is a problem it'd also affects other core > io_uring parts. In my current branch getting that situation is rather hard, but eventually got IO_URING_F_TASK_DEAD (>40 test rounds vs. every time before...) - with the initial patch version - I think my testing was flawed back that time. > >>> FWIW, the original version is how it's handled in several places >>> across io_uring, and the difference is a gap for !DEFER_TASKRUN >>> when a task_work is queued somewhere in between when a task is >>> started going through exit() but haven't got PF_EXITING set yet. >>> IOW, should be harder to hit. >>> >> >> Does that mean that the test for PF_EXITING is racy and we cannot >> entirely rely on it? > > No, the PF_EXITING check was fine, even though it'll look > different now for unrelated reasons. What I'm saying is that the > callback can get executed from the desired task, i.e. > req->task == current, but it can happen from a late exit(2)/etc. > path where the task is botched and likely doesn't have ->mm. > Ah ok, thanks for the info! Thanks, Bernd
