On 07/11/2020 00:51, Josef wrote: > On Sat, 7 Nov 2020 at 01:45, Josef <josef.grieb@xxxxxxxxx> wrote: >> I came across some strange behaviour in some netty-io_uring tests when >> using SQPOLL which seems like a bug to me, however I don't know how to >> reproduce it, as the error occurs randomly which leads to a kernel >> "freeze", I spend all day trying to figure out how to reproduce this >> error...any idea what the cause is? >> >> branch: for-5.11/io_uring >> last commit 34f98f655639b32f28c30c27dbbea57f8c304d9c >> >> (please don't waste your time as I'll take a look on the weekend) >> > I forgot to mention that same cores are running at 100% cpu usage, > when error occurs I haven't got the first email, is it "kernel NULL pointer dereference" as in the subject or just freeze? also - anything in dmesg? (>5 min after freeze) - did you locate which test hangs it? If so what it uses? e.g. SQPOLL sharing, IOPOLL., etc. - is it send/recvmsg, send/recv you use? any other? - does this happen often? - you may try `funcgraph __io_sq_thread -H` or even with `io_sq_thread` (funcgraph is from bpftools). Or catch that with some other tools. -- Pavel Begunkov
