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

From: KOSAKI Motohiro
Date: Mon Oct 26 2009 - 22:43:41 EST


> Testing by Frans Pop indicates that in the 2.6.30..2.6.31 window at
> least that the commits 373c0a7e 8aa7e847 dramatically increased the
> number of GFP_ATOMIC failures that were occuring within a wireless
> driver. It was never isolated which of the changes was the exact problem
> and it's possible it has been fixed since. If problems are still
> occuring with GFP_ATOMIC in 2.6.31-rc5, then this patch should be
> applied to determine if the congestion_wait() callers are still broken.

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.

I hope to try reproduce this problem on my test environment. Can anyone
please explain reproduce way?
Is special hardware necessary?


----------------------------------------------------
commit 8aa7e847d834ed937a9ad37a0f2ad5b8584c1ab0
Author: Jens Axboe <jens.axboe@xxxxxxxxxx>
Date: Thu Jul 9 14:52:32 2009 +0200

Fix congestion_wait() sync/async vs read/write confusion

Commit 1faa16d22877f4839bd433547d770c676d1d964c accidentally broke
the bdi congestion wait queue logic, causing us to wait on congestion
for WRITE (== 1) when we really wanted BLK_RW_ASYNC (== 0) instead.

Signed-off-by: Jens Axboe <jens.axboe@xxxxxxxxxx>



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