Re: [PATCH] xfs: don't do inodgc work if task is exiting

Tycho Andersen
2023-05-12T15:16:45Z

On Fri, May 12, 2023 at 11:45:47AM +1000, Dave Chinner wrote:
>
> Yeah, this is papering over the observed symptom, not addressing the
> root cause of the inodegc flush delay. What do you see when you run
> sysrq-w and sysrq-l? Are there inodegc worker threads blocked
> performing inodegc?

I will try this next time we encounter this.

> e.g. inodegc flushes could simply be delayed by an unlinked inode
> being processed that has millions of extents that need to be freed.
>
> In reality, inode reclaim can block for long periods of time
> on any filesystem, so the concept of "inode reclaim should
> not block when PF_EXITING" is not a behaviour that we guarantee
> anywhere or could guarantee across the board.
>
> Let's get to the bottom of why inodegc has apparently stalled before
> trying to work out how to fix it...

I'm happy to try, but I think it is also worth applying this patch.
Like I said in the other thread, having to evac a box to get rid of an
unkillable userspace process is annoying.

Thanks for the debugging tips.

Tycho