Modify the netlink code so that SOCK_VMIO has the desired effect on the user-space side of the connection. Modify sys_{send,recv}msg to use sk->sk_allocation instead of GFP_KERNEL, this should not change existing behaviour because the default of sk->sk_allocation is GFP_KERNEL, and no user-space exposed socket would have it any different at this time. This change allows the system calls to succeed for SOCK_VMIO sockets (who have sk->sk_allocation |= GFP_EMERGENCY) even under extreme memory pressure. Since netlink_sendmsg is used to transfer msgs from user- to kernel-space treat the skb allocation there as a receive allocation. Also export netlink_lookup, this is needed to locate the kernel side struct sock object associated with the user-space netlink socket. Signed-off-by: Peter Zijlstra Cc: David Miller Cc: Mike Christie --- include/linux/netlink.h | 1 + net/compat.c | 2 +- net/netlink/af_netlink.c | 12 +++++++++--- net/socket.c | 6 +++--- 4 files changed, 14 insertions(+), 7 deletions(-) Index: linux-2.6-git/net/netlink/af_netlink.c =================================================================== --- linux-2.6-git.orig/net/netlink/af_netlink.c +++ linux-2.6-git/net/netlink/af_netlink.c @@ -203,7 +203,7 @@ netlink_unlock_table(void) wake_up(&nl_table_wait); } -static __inline__ struct sock *netlink_lookup(int protocol, u32 pid) +struct sock *netlink_lookup(int protocol, u32 pid) { struct nl_pid_hash *hash = &nl_table[protocol].hash; struct hlist_head *head; @@ -1157,7 +1157,7 @@ static int netlink_sendmsg(struct kiocb if (len > sk->sk_sndbuf - 32) goto out; err = -ENOBUFS; - skb = alloc_skb(len, GFP_KERNEL); + skb = __alloc_skb(len, GFP_KERNEL, SKB_ALLOC_RX, -1); if (skb==NULL) goto out; @@ -1186,8 +1186,13 @@ static int netlink_sendmsg(struct kiocb } if (dst_group) { + gfp_t gfp_mask = sk->sk_allocation; + + if (skb_emergency(skb)) + gfp_mask |= __GFP_EMERGENCY; + atomic_inc(&skb->users); - netlink_broadcast(sk, skb, dst_pid, dst_group, GFP_KERNEL); + netlink_broadcast(sk, skb, dst_pid, dst_group, gfp_mask); } err = netlink_unicast(sk, skb, dst_pid, msg->msg_flags&MSG_DONTWAIT); @@ -1850,6 +1855,7 @@ panic: core_initcall(netlink_proto_init); +EXPORT_SYMBOL(netlink_lookup); EXPORT_SYMBOL(netlink_ack); EXPORT_SYMBOL(netlink_run_queue); EXPORT_SYMBOL(netlink_broadcast); Index: linux-2.6-git/net/socket.c =================================================================== --- linux-2.6-git.orig/net/socket.c +++ linux-2.6-git/net/socket.c @@ -1817,7 +1817,7 @@ asmlinkage long sys_sendmsg(int fd, stru err = -ENOMEM; iov_size = msg_sys.msg_iovlen * sizeof(struct iovec); if (msg_sys.msg_iovlen > UIO_FASTIOV) { - iov = sock_kmalloc(sock->sk, iov_size, GFP_KERNEL); + iov = sock_kmalloc(sock->sk, iov_size, sock->sk->sk_allocation); if (!iov) goto out_put; } @@ -1846,7 +1846,7 @@ asmlinkage long sys_sendmsg(int fd, stru ctl_len = msg_sys.msg_controllen; } else if (ctl_len) { if (ctl_len > sizeof(ctl)) { - ctl_buf = sock_kmalloc(sock->sk, ctl_len, GFP_KERNEL); + ctl_buf = sock_kmalloc(sock->sk, ctl_len, sock->sk->sk_allocation); if (ctl_buf == NULL) goto out_freeiov; } @@ -1922,7 +1922,7 @@ asmlinkage long sys_recvmsg(int fd, stru err = -ENOMEM; iov_size = msg_sys.msg_iovlen * sizeof(struct iovec); if (msg_sys.msg_iovlen > UIO_FASTIOV) { - iov = sock_kmalloc(sock->sk, iov_size, GFP_KERNEL); + iov = sock_kmalloc(sock->sk, iov_size, sock->sk->sk_allocation); if (!iov) goto out_put; } Index: linux-2.6-git/include/linux/netlink.h =================================================================== --- linux-2.6-git.orig/include/linux/netlink.h +++ linux-2.6-git/include/linux/netlink.h @@ -157,6 +157,7 @@ struct netlink_skb_parms #define NETLINK_CREDS(skb) (&NETLINK_CB((skb)).creds) +extern struct sock *netlink_lookup(int protocol, __u32 pid); extern struct sock *netlink_kernel_create(int unit, unsigned int groups, void (*input)(struct sock *sk, int len), struct mutex *cb_mutex, Index: linux-2.6-git/net/compat.c =================================================================== --- linux-2.6-git.orig/net/compat.c +++ linux-2.6-git/net/compat.c @@ -169,7 +169,7 @@ int cmsghdr_from_user_compat_to_kern(str * from the user. */ if (kcmlen > stackbuf_size) - kcmsg_base = kcmsg = sock_kmalloc(sk, kcmlen, GFP_KERNEL); + kcmsg_base = kcmsg = sock_kmalloc(sk, kcmlen, sk->sk_allocation); if (kcmsg == NULL) return -ENOBUFS; -- - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/