On 3/27/23 7:54?AM, Michael Ellerman wrote: > "Nicholas Piggin" <npig...@gmail.com> writes: >> On Mon Mar 27, 2023 at 8:15 AM AEST, Jens Axboe wrote: >>> Powerpc sets up PF_KTHREAD and PF_IO_WORKER with a NULL pt_regs, which >>> from my (arguably very short) checking is not commonly done for other >>> archs. This is fine, except when PF_IO_WORKER's have been created and >>> the task does something that causes a coredump to be generated. Then we >>> get this crash: >> >> Hey Jens, >> >> Thanks for the testing and the patch. >> >> I think your patch would work, but I'd be inclined to give the IO worker >> a pt_regs so it looks more like other archs and a regular user thread. >> >> Your IO worker bug reminded me to resurrect some copy_thread patches I >> had and I think they should do that >> >> https://lists.ozlabs.org/pipermail/linuxppc-dev/2023-March/256271.html >> >> I wouldn't ask you to test it until I've at least tried, do you have a >> test case that triggers this? > > I hit it once on one machine while running the mtr test from the other > thread. I'm not sure what leads to it failing that way rather than the > usual case of the mariadb test just printing an error.
That's how I hit it first too, then I wrote the reproducer to verify and be able to test a patch. -- Jens Axboe