On Sat, May 30, 2015 at 08:03:10AM -0400, Jeff Layton wrote: > Jerome reported seeing a warning pop when working with a swapfile on > NFS. The nfs_swap_activate can end up calling sk_set_memalloc while > holding the rcu_read_lock and that function can sleep. > > To fix that, we need to take a reference to the xprt while holding the > rcu_read_lock, set the socket up for swapping and then drop that > reference. But, xprt_put is not exported and having NFS deal with the > underlying xprt is a bit of layering violation anyway. > > Fix this by adding a set of activate/deactivate functions that take a > rpc_clnt pointer instead of an rpc_xprt, and have nfs_swap_activate and > nfs_swap_deactivate call those. > > Also, add a per-rpc_clnt atomic counter to keep track of the number of > active swapfiles associated with it. When the counter does a 0->1 > transition, we enable swapping on the xprt, when we do a 1->0 transition > we disable swapping on it. > > This also allows us to be a bit more selective with the RPC_TASK_SWAPPER > flag. If non-swapper and swapper clnts are sharing a xprt, then we only > need to flag the tasks from the swapper clnt with that flag. > > Cc: Mel Gorman <mgorman@xxxxxxx> > Reported-by: Jerome Marchand <jmarchan@xxxxxxxxxx> > Signed-off-by: Jeff Layton <jeff.layton@xxxxxxxxxxxxxxx> Acked-by: Mel Gorman <mgorman@xxxxxxx> -- Mel Gorman SUSE Labs -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>