Patch "rbd: use GFP_NOIO consistently for request allocations" has been added to the 4.4-stable tree

This is a note to let you know that I've just added the patch titled

rbd: use GFP_NOIO consistently for request allocations

to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
rbd-use-gfp_noio-consistently-for-request-allocations.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: David Disseldorp <[email protected]>
Date: Tue, 5 Apr 2016 11:13:39 +0200
Subject: rbd: use GFP_NOIO consistently for request allocations

From: David Disseldorp <[email protected]>

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.

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

@@ -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) {

Patches currently in stable-queue which might be from [email protected] are

queue-4.4/rbd-use-gfp_noio-consistently-for-request-allocations.patch