| From: | Heikki Linnakangas <hlinnakangas(at)vmware(dot)com> |
|---|---|
| To: | Christian Kruse <christian(at)2ndquadrant(dot)com> |
| Cc: | Jeff Janes <jeff(dot)janes(at)gmail(dot)com>, Andres Freund <andres(at)2ndquadrant(dot)com>, Abhijit Menon-Sen <ams(at)2ndquadrant(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: [PATCH] Use MAP_HUGETLB where supported (v3) |
| Date: | 2014-01-29 19:36:55 |
| Message-ID: | 52E95857.30503@vmware.com |
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| Lists: | pgsql-hackers |
On 01/29/2014 09:18 PM, Christian Kruse wrote:
> Hi,
>
> On 29/01/14 10:11, Jeff Janes wrote:
>> I'm getting this warning now with gcc (GCC) 4.4.7:
>
> Interesting. I don't get that warning. But the compiler is (formally)
> right.
>
>> pg_shmem.c: In function 'PGSharedMemoryCreate':
>> pg_shmem.c:332: warning: 'allocsize' may be used uninitialized in this
>> function
>> pg_shmem.c:332: note: 'allocsize' was declared here
Hmm, I didn't get that warning either.
> Attached patch should fix that.
That's not quite right. If the first mmap() fails, allocsize is set to
the rounded-up size, but the second mmap() uses the original size for
the allocation. So it returns a too high value to the caller.
Ugh, it's actually broken anyway :-(. The first allocation also passes
*size to mmap(), so the calculated rounded-up allocsize value is not
used for anything.
Fix pushed.
- Heikki
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