On Mon, 2022-01-17 at 10:09 -0600, Eric W. Biederman wrote: > Olivier Langlois <olivier@xxxxxxxxxxxxxx> writes: > From my perspective I am not at all convinced that io_uring is the > only > culprit. > > Beyond that the purpose of a coredump is to snapshot the process as > it > is, before anything is shutdown so that someone can examine the > coredump > and figure out what failed. Running around changing the state of the > process has a very real chance of hiding what is going wrong. > > Further your change requires that there be a place for io_uring to > clean > things up. Given that fundamentally that seems like the wrong thing > to > me I am not interested in making it easy to what looks like the wrong > thing. > > All of this may be perfection being the enemy of the good (especially > as > your io_uring magic happens as a special case in do_coredump). My > work > in this area is to remove hacks so I can be convinced the code works > 100% of the time so unfortunately I am not interested in pick up a > change that is only good enough. Someone else like Andrew Morton > might > be. > > Fair enough. You do bring good points but I am not so sure about the second one considering that the coredump is meant to be a snapshot and if io_uring still runs, the state may change as the dump is generated anyway. I'll follow with interest what you finally come up with but my mindset when I wrote the patch was that there does not seem to be any benefit keeping io_uring active while coredumping and it has the potential to create nasty issues. I did stumble into core file truncation problem. Pavel got that when modifying io_uring code: https://lore.kernel.org/all/1b519092-2ebf-3800-306d-c354c24a9ad1@xxxxxxxxx/ and I find very likely that keeping io_uring active while coredumping might create new nasty but subtle issues down the road... Greetings, Olivier
