On Fri, 27 May 2011 11:50:03 +0800
Bob Liu [off-list ref] wrote:

remap_pfn_range() does not update vma->end on no mmu arch which will
cause munmap() fail because it can't match the vma.

eg. fb_mmap() in fbmem.c will call io_remap_pfn_range() which is
remap_pfn_range() on nommu arch, if an address is not page aligned vma->start
will be changed in remap_pfn_range(), but neither size nor vma->end will be
updated. Then munmap(start, len) can't find the vma to free, because it need to
compare (start + len) with vma->end.

Also, I tagged the patch (or its successor) for -stable backporting as
the problem appears to be present in 2.6.38 (at least).

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