Re: [PATCH 0/5] Candidate fix for increased number of GFP_ATOMIC failures V2

[Pekka Enberg <penberg@cs.helsinki.fi>]

On Thu, Oct 22, 2009 at 5:22 PM, Mel Gorman <mel@csn.ul.ie> wrote:
> Test 1: Verify your problem occurs on 2.6.32-rc5 if you can
>
> Test 2: Apply the following two patches and test again
>
>  1/5 page allocator: Always wake kswapd when restarting an allocation attempt after direct reclaim failed
>  2/5 page allocator: Do not allow interrupts to use ALLOC_HARDER

These are pretty obvious bug fixes and should go to linux-next ASAP IMHO.

> Test 5: If things are still screwed, apply the following
>  5/5 Revert 373c0a7e, 8aa7e847: Fix congestion_wait() sync/async vs read/write confusion
>
>        Frans Pop reports that the bulk of his problems go away when this
>        patch is reverted on 2.6.31. There has been some confusion on why
>        exactly this patch was wrong but apparently the conversion was not
>        complete and further work was required. It's unknown if all the
>        necessary work exists in 2.6.31-rc5 or not. If there are still
>        allocation failures and applying this patch fixes the problem,
>        there are still snags that need to be ironed out.

As explained by Jens Axboe, this changes timing but is not the source
of the OOMs so the revert is bogus even if it "helps" on some
workloads. IIRC the person who reported the revert to help things did
report that the OOMs did not go away, they were simply harder to
trigger with the revert.

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