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SubjectRe: [PATCH] VM: Fix the gfp_mask in invalidate_complete_page2
On Fri, 06 Oct 2006 19:09:29 -0400
Steve Dickson <SteveD@redhat.com> wrote:

> >
> > It's not 100% clear what the gfp_t _means_ in the try_to_release_page()
> > context. Callees will rarely want to allocate memory (true?). So it
> > conveys two concepts:
> >
> > a) can sleep. (__GFP_WAIT). That's fairly straightforward
> >
> > b) can take fs locks (__GFP_FS). This is less clear. By passing down
> > __GFP_FS we're telling the callee that it's OK to take i_mutex, even
> > lock_page(). That sounds pretty unsafe in this context, particularly
> > the latter, as we're already holding a page lock.
> >
> > So perhaps the safer and more appropriate solution here is to pass in a
> > bare __GFP_WAIT.
> I agree... __GFP_WAIT does seem to be a bit more straightforward...
> either way is find.. as long as it cause NFS to flush its pages...

Except NFS looks at __GFP_FS, so __GFP_WAIT won't help.

Oh well. Passing __GFP_FS in here sort-of implies that it's OK to run
lock_page(), but if a ->releasepage() impementation tries to lock the page
it's passed then it needs its head read.

I made it GFP_KERNEL.
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