Re: [PATCHv5 3/5] ext4: mballoc: Introduce pcpu seqcnt for freeing PA to improve ENOSPC handling

[Ritesh Harjani]

On 6/9/20 3:50 PM, Borislav Petkov wrote:
> On Wed, Jun 03, 2020 at 03:40:16PM +0530, Ritesh Harjani wrote:
> > Yes, this is being discussed in the community.
> > I have submitted a patch which should help fix this warning msg.
> > Feel free to give this a try on your setup.
> >
> > https://marc.info/?l=linux-ext4&m=159110574414645&w=2
>
> I just triggered the same thing here too. Looking at your fix and not
> even pretending to know what's going on with that percpu sequence
> counting, I can't help but wonder why do you wanna do:
>
> 	seq = *raw_cpu_ptr(&discard_pa_seq);
>
> instead of simply doing:
>
> 	seq = this_cpu_read(discard_pa_seq);

That's correct. Thanks for pointing that out.
I guess in my development version of code I had seq as a u64 pointer
variable which later I had changed to u64 variable but I guess I
continued using pcpu ptr APIs for that.

Let me re-submit that patch with your Suggested-by tag and corresponding
changes.

-riteshh