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Date: Wed, 13 Feb 2002 16:52:34 -0200 (BRST)
From: Marcelo Tosatti <marcelo@conectiva.com.br>
To: Hugh Dickins <hugh@veritas.com>
Cc: Linus Torvalds <torvalds@transmeta.com>, Andrew Morton <akpm@zip.com.au>,
        Andrea Arcangeli <andrea@suse.de>,
        Rik van Riel <riel@conectiva.com.br>,
        "David S. Miller" <davem@redhat.com>,
        Benjamin LaHaise <bcrl@redhat.com>, Gerd Knorr <kraxel@bytesex.org>,
        Dave Jones <davej@suse.de>, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] __free_pages_ok oops
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On Tue, 12 Feb 2002, Hugh Dickins wrote:

> On Sat, 9 Feb 2002, Benjamin LaHaise wrote:
> > On Fri, Feb 08, 2002 at 05:46:56PM +0000, Hugh Dickins wrote:
> > > Ben, you probably have an AIO opinion here.  Is there a circumstance
> > > in which AIO can unpin a user page at interrupt time, after the
> > > calling task has (exited or) unmapped the page?
> > 
> > If the user unmaps the page, then aio is left holding the last reference 
> > to the page and will unmap it from irq or bh context (potentially task 
> > context too).  With networked aio, pages from userspace (anonymous or 
> > page cache pages) will be released by the network stack from bh context.  
> > Even now, I'm guess that should be possible with the zero copy flag...

Hugh. Are you sure we can free a page from IRQ/BH context with _current_
2.4 ? 

Please make sure so. 

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