Re: [PATCH] mm: fix page_mkclean_one

From: Mike Galbraith
Date: Thu Dec 28 2006 - 17:35:37 EST


On Thu, 2006-12-28 at 11:45 -0800, Andrew Morton wrote:
> On Thu, 28 Dec 2006 11:28:52 -0800 (PST)
> Linus Torvalds <torvalds@xxxxxxxx> wrote:
>
> >
> >
> > On Thu, 28 Dec 2006, Guillaume Chazarain wrote:
> > >
> > > The attached patch fixes the corruption for me.
> >
> > Well, that's a good hint, but it's really just a symptom. You effectively
> > just made the test-program not even try to flush the data to disk, so the
> > page cache would stay in memory, and you'd not see the corruption as well.
> >
> > So you basically disabled the code that tried to trigger the bug more
> > easily.
> >
> > But the reason I say it's interesting is that "WB_SYNC_NONE" is very much
> > implicated in mm/page-writeback.c, and if there is a bug triggered by
> > WB_SYNC_NONE writebacks, then that would explain why page-writeback.c also
> > fails..
> >
>
> It would be interesting to convert your app to do fsync() before
> FADV_DONTNEED. That would take WB_SYNC_NONE out of the picture as well
> (apart from pdflush activity).

I did fdatasync(), tried remapping before unmapping... nogo here.

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