Messages in this thread | | | Date | Tue, 15 Feb 2011 18:01:52 +0100 | From | Andrea Arcangeli <> | Subject | Re: [PATCH 0/5] fix up /proc/$pid/smaps to not split huge pages |
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On Tue, Feb 15, 2011 at 11:55:10AM -0500, Eric B Munson wrote: > I am noticing in smaps that KernelPageSize is wrong of areas > that have been merged into THP. For instance: > > 7ff852a00000-7ff852c00000 rw-p 00000000 00:00 0 > Size: 2048 kB > Rss: 2048 kB > Pss: 2048 kB > Shared_Clean: 0 kB > Shared_Dirty: 0 kB > Private_Clean: 0 kB > Private_Dirty: 2048 kB > Referenced: 2048 kB > Anonymous: 2048 kB > AnonHugePages: 2048 kB > Swap: 0 kB > KernelPageSize: 4 kB > MMUPageSize: 4 kB > Locked: 0 kB > > The entire mapping is contained in a THP but the > KernelPageSize shows 4kb. For cases where the mapping might > have mixed page sizes this may be okay, but for this > particular mapping the 4kb page size is wrong.
I'm not sure this is a bug, if the mapping grows it may become 4096k but the new pages may be 4k. There's no such thing as a vma_mmu_pagesize in terms of hugepages because we support graceful fallback and collapse/split on the fly without altering the vma. So I think 4k is correct here.
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