From: Lennert Buytenhek <[EMAIL PROTECTED]> Date: Mon, 28 May 2007 16:39:36 +0200
> On Mon, May 28, 2007 at 09:17:55AM -0500, James Bottomley wrote: > > > > > Ok, output on parisc is: > > > > > > > > [EMAIL PROTECTED]:~$ ./a.out > > > > firstfirstfirst > > > > firstfirstfirst > > > > secondsecondsec > > > > > > > > Which is correct. It remains correct even if I drop the msync(). > > > > > > With Lennert's new program, I get mostly: > > > > > > firstfirstfirst > > > firstfirstfirst > > > firstfirstfirst > > > > > > but occasionally: > > > > > > firstfirstfirst > > > firstfirstfirst > > > secondsecondsec > > > > > > However, if I open code the memcpy() in the MAPREAD to copy one word > > > at a time, then I reliably get the "secondsecondsec" line. But if I > > > convert the memcpy() in MAPWRITE in the same way, I'm back to mostly > > > getting the failure with the occasional success. Utterly confused. > > > > > > Unless someone's got a theory, I'm stumped. > > > > I think you're not flushing correctly in munmap() ... but I'm not sure > > the linux API actually requires this. > > Having to (conditionally) invalidate the kernel direct mapping for > every userland page we unmap would kind of suck.. You don't have to do it for all pages, you just have to do whatever flush_dcache_page() would do, for dirty+shared+writable mmap()'s of files. unmap's of shared+writable regions of files are so rare, only test programs and the odd database do it when they shut down. - 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
