Messages in this thread | | | Date | Thu, 26 Mar 2009 23:43:03 -0700 (PDT) | From | sidc7 <> | Subject | Re: Copy-on-write |
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> If the source and destination pages are not in high memory (exactly > where this boundary is depends on your architecture) they do not need > to be mapped before copying. See cow_user_page in mm/memory.c, > copy_user_highpage in include/linux/highmem.h and kmap_atomic in > arch/x86/mm/highmem_32.c (as well as implementations for other > architectures)
> Note that on 64-bit platforms, generally there will be no high memory, > and so remappings will never be needed to carry out a COW.
Thanks for the quick reply. In general if the kernel wishes to read any arbitrary page mapped to an application's address space, will the kernel cause a page fault on that page, since the page is currently not in its address space and the kernel is wishing to read from this page?
Thanks
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