Re: [PATCH v2 0/9] page_owner improvements for debugging

Michal Hocko
2015-11-25T14:30:15Z

On Tue 24-11-15 13:36:12, Vlastimil Babka wrote:
[...]
> For the last point, Kirill requested a human readable printing of gfp_mask and
> migratetype after v1. At that point it probably makes a lot of sense to do the
> same for page alloc failure and OOM warnings. The flags have been undergoing
> revisions recently, and we might be getting reports from various kernel
> versions that differ. The ./scripts/gfp-translate tool needs to be pointed at
> the corresponding sources to be accurate. The downside is potentially breaking
> scripts that grep these warnings, but it's not a first change done there over
> the years.

Yes this is very helpful! Thanks for doing this.

> Note I'm not entirely happy about the dump_gfpflag_names() implementation, due
> to usage of pr_cont() unreliable on SMP (and I've seen spurious newlines in
> dmesg output, while being correct on serial console or /var/log/messages).
> It also doesn't allow plugging the gfp_mask translation into
> /sys/kernel/debug/page_owner where it also could make sense. Maybe a new
> *printf formatting flag?

I wouldn't object. gfp_mask has its own "type" so having a specific
formatter sounds like a good idea to me.

--
Michal Hocko
SUSE Labs