Re: 2.6.26-rc5-mm3: BUG large value for HugePages_Rsvd

From: Jon Tollefson
Date: Thu Jun 19 2008 - 23:18:46 EST


Andy Whitcroft wrote:
On Thu, Jun 19, 2008 at 11:27:47AM -0500, Jon Tollefson wrote:
After running some of the libhugetlbfs tests the value for
/proc/meminfo/HugePages_Rsvd becomes really large. It looks like it has
wrapped backwards from zero.
Below is the sequence I used to run one of the tests that causes this;
the tests passes for what it is intended to test but leaves a large
value for reserved pages and that seemed strange to me.
test run on ppc64 with 16M huge pages

Yes Adam reported that here yesterday, he found it in his hugetlfs testing.
I have done some investigation on it and it is being triggered by a bug in
the private reservation tracking patches. It is triggered by the hugetlb
test which causes some complex vma splits to occur on a private mapping.
sorry I missed that

I believe I have the underlying problem nailed and do have some nearly
complete patches for this and they should be in a postable state by
tommorrow.
Cool.
-apw
Jon

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