Messages in this thread | | | Date | Thu, 27 Nov 2008 09:59:27 -0700 | From | Matthew Wilcox <> | Subject | Re: [PATCH] FRV: Fix mmap2 error handling |
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On Thu, Nov 27, 2008 at 03:12:38PM +0000, David Howells wrote: > Fix the error handling in sys_mmap2(). Currently, if the pgoff check fails, > fput() might have to be called (which it isn't), so do the pgoff check first, > before fget() is called.
*sigh*.
My reaction was "Why do we have sys_mmap2 in every architecture?" So I started looking. Oh dear, oh dear oh dear.
FRV: /* As with sparc32, make sure the shift for mmap2 is constant (12), no matter what PAGE_SIZE we have.... */ ia64: Just uses PAGE_SIZE (currently supported values: 4k, 8k, 16k and 64k).
So what is poor userspace to do? Check which architecture it's on and figure out what PAGE_SIZE to use for mmap2 based on that?
How about we introduce a sys_mmap6() in common code which takes 'off' in multiples of 4k. Then FRV and other sane architectures can replace their sys_mmap2 entries in their syscall tables with sys_mmap6. ia64 has to keep its insane sys_mmap2 entry, but it can add a sys_mmap6 entry too.
-- Matthew Wilcox Intel Open Source Technology Centre "Bill, look, we understand that you're interested in selling us this operating system, but compare it to ours. We can't possibly take such a retrograde step."
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