Subject: Re: [PATCH 5/5] ONLY-APPLY-IF-STILL-FAILING Revert 373c0a7e, 8aa7e847: Fix congestion_wait() sync/async vs read/write confusion

From: Frans Pop <[email-masked]>
Date: Tue, 27 Oct 2009 11:29:01 +0100

On Tuesday 27 October 2009, KOSAKI Motohiro wrote:
> Oops. no, please no.
> 8aa7e847 is regression fixing commit. this revert indicate the
> regression occur again.
> if we really need to revert it, we need to revert 1faa16d2287 too.
> however, I doubt this commit really cause regression to iwlan. IOW,
> I agree Jens.

This is not intended as a patch for mainline, but just as a test to see if 
it improves things. It may be a regression fix, but it also creates a 
significant change in behavior during swapping in my test case.
If a fix is needed, it will probably by different from this revert.
Please read: http://lkml.org/lkml/2009/10/26/510.

This mail has some data: http://lkml.org/lkml/2009/10/26/455.

> I hope to try reproduce this problem on my test environment. Can anyone
> please explain reproduce way?

Please see my mails in this thread for bug #14141: 
http://thread.gmane.org/gmane.linux.kernel/896714

You will probably need to read some of them to understand the context of 
the two mails linked above.

The most relevant ones are (all from the same thread; not sure why gmane 
gives such weird links):
http://article.gmane.org/gmane.linux.kernel.mm/39909
http://article.gmane.org/gmane.linux.kernel.kernel-testers/7228
http://article.gmane.org/gmane.linux.kernel.kernel-testers/7165

> Is special hardware necessary?

Not special hardware, but you may need an encrypted partition and NFS; the 
test may need to be modified according to the amount of memory you have.
I think it should be possible to reproduce the freezes I see while ignoring 
the SKB allocation errors as IMO those are just a symptom, not the cause.
So you should not need wireless.

The severity of the freezes during my test often increases if the test is 
repeated (without rebooting).

Cheers,
FJP

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