[PATCH 4.4 096/137] rbd: use GFP_NOIO consistently for request allocations

From: Greg Kroah-Hartman
Date: Sun Apr 17 2016 - 22:51:51 EST


4.4-stable review patch. If anyone has any objections, please let me know.

------------------

From: David Disseldorp <ddiss@xxxxxxx>

commit 2224d879c7c0f85c14183ef82eb48bd875ceb599 upstream.

As of 5a60e87603c4c533492c515b7f62578189b03c9c, RBD object request
allocations are made via rbd_obj_request_create() with GFP_NOIO.
However, subsequent OSD request allocations in rbd_osd_req_create*()
use GFP_ATOMIC.

With heavy page cache usage (e.g. OSDs running on same host as krbd
client), rbd_osd_req_create() order-1 GFP_ATOMIC allocations have been
observed to fail, where direct reclaim would have allowed GFP_NOIO
allocations to succeed.

Suggested-by: Vlastimil Babka <vbabka@xxxxxxx>
Suggested-by: Neil Brown <neilb@xxxxxxxx>
Signed-off-by: David Disseldorp <ddiss@xxxxxxx>
Signed-off-by: Ilya Dryomov <idryomov@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
drivers/block/rbd.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -1955,7 +1955,7 @@ static struct ceph_osd_request *rbd_osd_

osdc = &rbd_dev->rbd_client->client->osdc;
osd_req = ceph_osdc_alloc_request(osdc, snapc, num_ops, false,
- GFP_ATOMIC);
+ GFP_NOIO);
if (!osd_req)
return NULL; /* ENOMEM */

@@ -2004,7 +2004,7 @@ rbd_osd_req_create_copyup(struct rbd_obj
rbd_dev = img_request->rbd_dev;
osdc = &rbd_dev->rbd_client->client->osdc;
osd_req = ceph_osdc_alloc_request(osdc, snapc, num_osd_ops,
- false, GFP_ATOMIC);
+ false, GFP_NOIO);
if (!osd_req)
return NULL; /* ENOMEM */

@@ -2506,7 +2506,7 @@ static int rbd_img_request_fill(struct r
bio_chain_clone_range(&bio_list,
&bio_offset,
clone_size,
- GFP_ATOMIC);
+ GFP_NOIO);
if (!obj_request->bio_list)
goto out_unwind;
} else if (type == OBJ_REQUEST_PAGES) {