Intermittent storage (dm-crypt?) freeze - regression 6.4->6.5

[Mikulas Patocka]

On Wed, 1 Nov 2023, Hannes Reinecke wrote:

> And that is something I've been wondering (for quite some time now):
> What _is_ the appropriate error handling for -ENOMEM?
> At this time, we assume it to be a retryable error and re-run the queue
> in the hope that things will sort itself out.
> But if they don't we're stuck.
> Can we somehow figure out if we make progress during submission, and (at
> least) issue a warning once we detect a stall?

The appropriate way is to use mempools. mempool_alloc (with 
__GFP_DIRECT_RECLAIM) can't ever fail.

But some kernel code does GFP_NOIO allocations in the I/O path and the 
authors hope that they get away with it.

Mikulas