On Mon 12-12-16 12:49:03, Petr Mladek wrote:

On Mon 2016-12-12 10:07:03, Michal Hocko wrote:

quoted

On Sat 10-12-16 20:24:57, Tetsuo Handa wrote:

[...]

quoted

quoted

The introduction of uncontrolled

  warn_alloc(gfp_mask, "page allocation stalls for %ums, order:%u", ...);

I am just curious that there would be so many messages.
If I get it correctly, this warning is printed
once every 10 second. Or am I wrong?

Yes it is once per 10s per allocation context. Tetsuo's test case is
generating hundreds of such allocation paths which are hitting the
warn_alloc path. So they can meet there and generate a lot of output.
Now we have __ratelimit here which should help but most probably needs
some better tunning.

I am also considering to use a per warn_alloc lock which would also help
to make the output nicer (not interleaving for parallel callers).

Well, you might want to consider using

		stall_timeout *= 2;

instead of adding the constant 10 * HZ.

This wouldn't help in the above situation.
-- 
Michal Hocko
SUSE Labs

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