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Message-ID: <3C6227B7.37BFA2EC@zip.com.au>
Date: Wed, 06 Feb 2002 23:07:35 -0800
From: Andrew Morton <akpm@zip.com.au>
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To: "David S. Miller" <davem@redhat.com>
CC: bcrl@redhat.com, hugh@veritas.com, marcelo@conectiva.com.br,
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Subject: Re: [PATCH] __free_pages_ok oops
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"David S. Miller" wrote:
> 
>    From: Andrew Morton <akpm@zip.com.au>
>    Date: Wed, 06 Feb 2002 22:19:32 -0800
> 
>    It's only a problem if this is the final put_page().  In the
>    case of sendfile(), process-context code can be taught to take
>    a temporary reference on the page, and only release it after the network
>    stack is known to have finished with the page. sendfile is synchronous, yes?
> 
> Userspace can return long before the SKBs are free'd up.  That SKB
> free doesn't happen until the ACKs come back from the receiver.

I feel that presence on the lru list should contribute to
page->count.  It seems a bit weird and kludgy that this
is not so.

If we were to do this then would this not fix networking's
problem?  The skb free wouldn't release the page - it would
be left on the LRU with ->count == 1 and kswapd would reap it.

(Says me, hoping that Hugh will code it :))

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