From: Andrew Morton <[email protected]>
Date: Thu, 19 Oct 2006 00:17:47 -0700
> On Thu, 19 Oct 2006 00:00:27 -0700 (PDT)
> David Miller <[email protected]> wrote:
>
> > Unfortunately, the kernel has just touched the page and thus there are
> > active cache lines for the kernel side mapping. When we map this into
> > user space, userspace might see stale cachelines instead of the
> > memset() stores.
>
> hm. Has it always been that way or did something change?
Always.
> > Architectures typically take care of this in copy_user_page() and
> > clear_user_page(). The absolutely depend upon those two routines
> > being used for anonymous pages, and handle the D-cache issues there.
>
> Only anonymous pages? There are zillions of places where we modify
> pagecache without a flush, especially against the blockdev mapping (fs
> metadata).
It's cpu stores that matter, not device DMA and the like, and we have
flush_dcache_page() calls in the correct spots. You can see that
we take care of this even in places such as the loop driver :-)
-
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/
[Index of Archives]
[Kernel Newbies]
[Netfilter]
[Bugtraq]
[Photo]
[Stuff]
[Gimp]
[Yosemite News]
[MIPS Linux]
[ARM Linux]
[Linux Security]
[Linux RAID]
[Video 4 Linux]
[Linux for the blind]
[Linux Resources]
