Re: [patch] cache flush bug in mm/filemap.c (all kernels >= 2.5.30(atleast))

[Mika Penttilä (mika.penttila@kolumbus.fi)]

I don't think the flush_dcache_page thing is done almost anywhere in the 
block/driver level right now. And we shouldn't be doing io reads to 
pagecache pages with user mappings anyway normally. direct-io is a 
different thing.

--Mika


David S. Miller wrote:

> On Fri, 2003-05-23 at 11:34, Russell King wrote:
>  
>
> > So no, I don't think it is a device driver issue at all.
> >
> > DaveM?
> >    
>
> Oh yes, this part is.  If you don't ensure this, everything
> breaks.
>
> At the end of an I/O operation, say to a page cache page, that
> data ought to be visible equally to a userspace vs. a kernel
> space mapping to that page.
>
> For example, this is why we use language about "cpu visibility" in the
> DMA api documentation and not "kernel cpu visibility" :-)  And because
> PIO transfers are basically pseudo-DMA they need to make the same exact
> guarentees.
>
> If you've been living in a world where you didn't think this is
> necessary, I certainly feel bad for you :-)
>
>  


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