On Tue, May 15, 2012 at 11:47:14AM +0200, Peter Zijlstra wrote: > On Tue, 2012-05-15 at 10:14 +0100, Mel Gorman wrote: > > @@ -289,6 +289,18 @@ void sk_clear_memalloc(struct sock *sk) > > sock_reset_flag(sk, SOCK_MEMALLOC); > > sk->sk_allocation &= ~__GFP_MEMALLOC; > > static_key_slow_dec(&memalloc_socks); > > + > > + /* > > + * SOCK_MEMALLOC is allowed to ignore rmem limits to ensure forward > > + * progress of swapping. However, if SOCK_MEMALLOC is cleared while > > + * it has rmem allocations there is a risk that the user of the > > + * socket cannot make forward progress due to exceeding the rmem > > + * limits. By rights, sk_clear_memalloc() should only be called > > + * on sockets being torn down but warn and reset the accounting if > > + * that assumption breaks. > > + */ > > + if (WARN_ON(sk->sk_forward_alloc)) > > WARN_ON_ONCE() perhaps? > I do not expect SOCK_MEMALLOC to be cleared frequently at all with the possible exception of swapon/swapoff stress tests. If the flag is being cleared regularly with rmem tokens then that is interesting in itself but a WARN_ON_ONCE would miss it. > > + sk_mem_reclaim(sk); > > } -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>