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>