> > > > > > Yes, note the flush_dcache_page() call in fuse_copy_finish(). That > > > > > > could be replaced by the flush_kernel_dcache_page() (added by James > > > > > > Bottomley together with flush_anon_page()) when all relevant > > > > > > architectures have defined it. > > > > > > > > > > I should say that flush_anon_page() in its current form is going to be > > > > > problematic for ARM. It is passed: > > > > > > > > > > 1. the struct page > > > > > 2. the virtual address in process memory for the page > > > > > > > > > > It is not passed the mm or vma. This means that we have no idea > > > > > whether > > > > > the virtual address is in the currently mapped VM space or not. The > > > > > common use of get_area_pages() is to get pages from other address > > > > > spaces. > > > > > > > > I'm not sure I understand. flush_anon_page() needs only to flush the > > > > mapping for the given virtual address, no? > > > > > > Yes, but that virtual /user/ address is meaningless without knowing > > > which process address space it belongs to. > > > > > > > It's always mapped at that address (since it was just accessed through > > > > that). > > > > > > No. Consider ptrace() (invoked by gdb) reading data from another > > > processes address space to obtain structure data or instructions. > > > > > > > Any other mappings > > > > of the anonymous page are irrelevant, they don't need to be flushed. > > > > > > Again, incorrect. Consider if the page you're accessing is a file- > > > backed page, and is mapped into a process using a shared mapping. > > > Because you've written to the file, those shared mappings need to see > > > that write, and the interface for achieving that is flush_dcache_page(). > > > If not, data loss can occur. > > > > Yes, for file backed pages. But flush_anon_page() only needs to deal > > with anonymous (not file backed) pages. > > Ignore my final paragraph, it was clearly wrong; I was thinking about > the flush after you've written to the page. > > However, I continue to assert that I require the VMA to implement > flush_anon_page() since a userspace address without knowing which > userspace it corresponds with is utterly useless for cache maintainence > purposes.
I understand now. I'm not sure how the PARISC implementation can be correct in this light. Miklos - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
