Re: [PATCH] mm: Drop "PFNs busy" printk in an expected path.

From: Eric Anholt
Date: Thu Dec 29 2016 - 18:17:30 EST

Michal Nazarewicz <mina86@xxxxxxxxxx> writes:

> On Thu, Dec 29 2016, Eric Anholt wrote:
>> Michal Hocko <mhocko@xxxxxxxxxx> writes:
>>> This has been already brought up
>>> and there
>>> was a proposed patch for that which ratelimited the output
>>> resp.
>>> then the email thread just died out because the issue turned out to be a
>>> configuration issue. Michal indicated that the message might be useful
>>> so dropping it completely seems like a bad idea. I do agree that
>>> something has to be done about that though. Can we reconsider the
>>> ratelimit thing?
>> I agree that the rate of the message has gone up during 4.9 -- it used
>> to be a few per second.
> Sounds like a regression which should be fixed.
> This is why I donât think removing the message is a good idea. If you
> suddenly see a lot of those messages, something changed for the worse.
> If you remove this message, you will never know.
>> However, if this is an expected path during normal operation,
> This depends on your definition of âexpectedâ and ânormalâ.
> In general, I would argue that the fact those ever happen is a bug
> somewhere in the kernel â if memory is allocated as movable, it should
> be movable damn it!

I was taking "expected" from dae803e165a11bc88ca8dbc07a11077caf97bbcb --
if this is a actually a bug, how do we go about debugging it?

I've had Raspbian carrying a patch downstream to remove the error
message for 2 years now, and I either need to get this fixed or get this
patch merged to Fedora and Debian as well, now that they're shipping
some support for Raspberry Pi.

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