On Sun, May 27, 2007 at 07:31:27PM -0500, James Bottomley wrote: > On munmap we do a flush_cache_range for the unmapped vmas ... we > have to, otherwise the data might be lost as the user mapping is > zapped and we wouldn't be able to guarantee coherency writing it > to the backing store.
As far as I understand it, the munmap() does flush out the copy of the data at the user virtual address, but the subsequent read() call reads from an address in the kernel direct mapped window, for which there is still data in the cache due to the earlier read() syscall, and the mapping_writably_mapped() test fails so we don't end up calling flush_dcache_page(). - To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
