Re: [PATCH v2] mm: page_alloc: dump migrate-failed pages

From: Matthew Wilcox
Date: Wed Mar 10 2021 - 08:33:23 EST


On Tue, Mar 09, 2021 at 10:32:51AM +0100, Michal Hocko wrote:
> Apart from the above, do we have to warn for something that is a
> debugging aid? A similar concern wrt dump_page which uses pr_warn and
> page owner is using even pr_alert.
> Would it make sense to add a loglevel parameter both into __dump_page
> and dump_page_owner?

No. What would make sense is turning __dump_page() inside-out.
Something like printk("%pP\n");

In lib/vsprintf.c, there's a big switch statement in the function
pointer() that handles printing things like IPv6 addresses, dentries,
and function symbols.

Then we can do whatever we want around the new %pP, including choosing
the log level, adding additional information, choosing to dump the page
to a sysfs file, etc, etc.