On Wed, Dec 4, 2024 at 10:23 PM Sergey Senozhatsky <senozhatsky@xxxxxxxxxxxx> wrote: > > On (24/12/04 09:51), Brian Geffon wrote: > > > > > >> > > > > > >> In those cases 1 minute fuse timeout will overshot HUNG_TASK_TIMEOUT > > > > > >> and then the question is whether HUNG_TASK_PANIC is set. > > > > In my opinion this is a good argument for having the hung task timeout > > and a fuse timeout independent. The hung task timeout is for hung > > kernel threads > > Sorry, but no, it's not only for kernel threads. > > > in this situation we're potentially taking too long in > > userspace but that doesn't necessarily mean the system is hung. > > And it's not for hung system. It's for tasks that stuck unreasonably > long waiting for a particular event or resource. And those tasks very > well can be user-space processes, being stuck in syscall waiting for > something. > > > I think a loop which does an interruptible wait with a timeout of 1/2 > > the hung task timeout would make sense to ensure the hung task timeout > > doesn't hit. > > The point here is not to silent watchdog, we might as well just disable > it and call it a day. The point here is that fuse can be used (and IS > in our particular case) as a network filesystem, and the problem can be > way outside of your system, so spinning in a wait loop doesn't fix any > problem on that remote system no matter how long we spin, and that's > what watchdog signals us. Sergey, to clarify again what I was suggesting, I was not suggesting that no timeout is appropriate. I suggested that the hung task timeout is not appropriate and instead we should be using a different timeout. My suggestion about looping was simply to say: **once we've transitioned to userspace to service the request the hung task timeout should not apply and instead a different fuse timeout should.** The loop is nothing more than to allow the task to break out of the wait so it's not triggering the hung task timeout and frankly an implementation detail that I should have probably omitted. There are situations where a timeout less than the hung task timeout might be appropriate and there are situations where a timeout longer than the hung task timeout might be appropriate.
