lkml.org 
[lkml]   [2007]   [Oct]   [16]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: msync(2) bug(?), returns AOP_WRITEPAGE_ACTIVATE to userland
In message <84144f020710150447o94b1babo8b6e6a647828465f@mail.gmail.com>, "Pekka Enberg" writes:
> Hi,
>
> On 10/15/07, Erez Zadok <ezk@cs.sunysb.edu> wrote:
> > Pekka, with a small change to your patch (to handle time-based cache
> > coherency), your patch worked well and passed all my tests. Thanks.
> >
> > So now I wonder if we still need the patch to prevent AOP_WRITEPAGE_ACTIVATE
> > from being returned to userland. I guess we still need it, b/c even with
> > your patch, generic_writepages() can return AOP_WRITEPAGE_ACTIVATE back to
> > the VFS and we need to ensure that doesn't "leak" outside the kernel.
>
> I wonder whether _not setting_ BDI_CAP_NO_WRITEBACK implies that
> ->writepage() will never return AOP_WRITEPAGE_ACTIVATE for
> !wbc->for_reclaim case which would explain why we haven't hit this bug
> before. Hugh, Andrew?
>
> And btw, I think we need to fix ecryptfs too.

Yes, ecryptfs needs this fix too (and probably a couple of other mmap fixes
I've made to unionfs recently -- Mike Halcrow already knows :-)

Of course, running ecryptfs on top of tmpfs is somewhat odd and uncommon;
but with unionfs, users use tmpfs as the copyup branch very often.

> Pekka

Erez.
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2007-10-16 20:07    [W:0.283 / U:0.016 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site