Re: [PATCH 01/12] netvm: Prevent a stream-specific deadlock

From: Mel Gorman
Date: Wed Jun 20 2012 - 10:21:27 EST


On Wed, Jun 20, 2012 at 10:37:50AM +0100, Mel Gorman wrote:
> It could happen that all !SOCK_MEMALLOC sockets have buffered so
> much data that we're over the global rmem limit. This will prevent
> SOCK_MEMALLOC buffers from receiving data, which will prevent userspace
> from running, which is needed to reduce the buffered data.
>
> Fix this by exempting the SOCK_MEMALLOC sockets from the rmem limit.
> Once this change it applied, it is important that sockets that set
> SOCK_MEMALLOC do not clear the flag until the socket is being torn down.
> If this happens, a warning is generated and the tokens reclaimed to
> avoid accounting errors until the bug is fixed.
>
> [davem@xxxxxxxxxxxxx: Warning about clearing SOCK_MEMALLOC]
> Signed-off-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
> Signed-off-by: Mel Gorman <mgorman@xxxxxxx>
> Acked-by: David S. Miller <davem@xxxxxxxxxxxxx>

This patch introduced a new warning that I had previously missed. I'll
fix it up when rebasing this series on top of linux-next.

--
Mel Gorman
SUSE Labs
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