From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756319Ab2BFXCs (ORCPT ); Mon, 6 Feb 2012 18:02:48 -0500 Received: from cantor2.suse.de ([195.135.220.15]:48292 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756079Ab2BFW4c (ORCPT ); Mon, 6 Feb 2012 17:56:32 -0500 From: Mel Gorman To: Andrew Morton Cc: Linux-MM , Linux-Netdev , LKML , David Miller , Neil Brown , Peter Zijlstra , Mel Gorman Subject: [PATCH 13/15] nbd: Set SOCK_MEMALLOC for access to PFMEMALLOC reserves Date: Mon, 6 Feb 2012 22:56:16 +0000 Message-Id: <1328568978-17553-14-git-send-email-mgorman@suse.de> X-Mailer: git-send-email 1.7.3.4 In-Reply-To: <1328568978-17553-1-git-send-email-mgorman@suse.de> References: <1328568978-17553-1-git-send-email-mgorman@suse.de> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Set SOCK_MEMALLOC on the NBD socket to allow access to PFMEMALLOC reserves so pages backed by NBD, particularly if swap related, can be cleaned to prevent the machine being deadlocked. It is still possible that the PFMEMALLOC reserves get depleted resulting in deadlock but this can be resolved by the administrator by increasing min_free_kbytes. Signed-off-by: Mel Gorman --- drivers/block/nbd.c | 6 +++++- 1 files changed, 5 insertions(+), 1 deletions(-) diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c index c3f0ee1..45de594 100644 --- a/drivers/block/nbd.c +++ b/drivers/block/nbd.c @@ -155,6 +155,7 @@ static int sock_xmit(struct nbd_device *lo, int send, void *buf, int size, struct msghdr msg; struct kvec iov; sigset_t blocked, oldset; + unsigned long pflags = current->flags; if (unlikely(!sock)) { dev_err(disk_to_dev(lo->disk), @@ -168,8 +169,9 @@ static int sock_xmit(struct nbd_device *lo, int send, void *buf, int size, siginitsetinv(&blocked, sigmask(SIGKILL)); sigprocmask(SIG_SETMASK, &blocked, &oldset); + current->flags |= PF_MEMALLOC; do { - sock->sk->sk_allocation = GFP_NOIO; + sock->sk->sk_allocation = GFP_NOIO | __GFP_MEMALLOC; iov.iov_base = buf; iov.iov_len = size; msg.msg_name = NULL; @@ -215,6 +217,7 @@ static int sock_xmit(struct nbd_device *lo, int send, void *buf, int size, } while (size > 0); sigprocmask(SIG_SETMASK, &oldset, NULL); + tsk_restore_flags(current, pflags, PF_MEMALLOC); return result; } @@ -405,6 +408,7 @@ static int nbd_do_it(struct nbd_device *lo) BUG_ON(lo->magic != LO_MAGIC); + sk_set_memalloc(lo->sock->sk); lo->pid = task_pid_nr(current); ret = device_create_file(disk_to_dev(lo->disk), &pid_attr); if (ret) { -- 1.7.3.4