[PATCH 14/16] nbd: Set SOCK_MEMALLOC for access to PFMEMALLOC reserves
From: Mel Gorman <mgorman@suse.de>
Date: 2012-06-22 14:31:08
Also in:
linux-mm, lkml
Subsystem:
block layer, network block device (nbd), the rest · Maintainers:
Jens Axboe, Josef Bacik, Linus Torvalds
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 <mgorman@suse.de> --- drivers/block/nbd.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index 061427a75d..76bc96f 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c@@ -154,6 +154,7 @@ static int sock_xmit(struct nbd_device *nbd, 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(nbd->disk),
@@ -167,8 +168,9 @@ static int sock_xmit(struct nbd_device *nbd, 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;
@@ -214,6 +216,7 @@ static int sock_xmit(struct nbd_device *nbd, 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 *nbd) BUG_ON(nbd->magic != NBD_MAGIC); + sk_set_memalloc(nbd->sock->sk); nbd->pid = task_pid_nr(current); ret = device_create_file(disk_to_dev(nbd->disk), &pid_attr); if (ret) {
--
1.7.9.2
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