xen/blkfront: fix memory allocation flags in blkfront_setup_indirect()

Commit Message

Jürgen Groß April 3, 2020, 9 a.m. UTC

Commit 1d5c76e664333 ("xen-blkfront: switch kcalloc to kvcalloc for
large array allocation") didn't fix the issue it was meant to, as the
flags for allocating the memory are GFP_NOIO, which will lead the
memory allocation falling back to kmalloc().

So instead of GFP_NOIO use GFP_KERNEL and do all the memory allocation
in blkfront_setup_indirect() in a memalloc_noio_{save,restore} section.

Fixes: 1d5c76e664333 ("xen-blkfront: switch kcalloc to kvcalloc for large array allocation")
Cc: [e-mail]
Signed-off-by: Juergen Gross <[e-mail]>
---
 drivers/block/xen-blkfront.c | 17 ++++++++++++-----
 1 file changed, 12 insertions(+), 5 deletions(-)

Comments

Boris Ostrovsky April 3, 2020, 9:53 p.m. UTC | #1

On 4/3/20 5:00 AM, Juergen Gross wrote:
> Commit 1d5c76e664333 ("xen-blkfront: switch kcalloc to kvcalloc for
> large array allocation") didn't fix the issue it was meant to, as the
> flags for allocating the memory are GFP_NOIO, which will lead the
> memory allocation falling back to kmalloc().
>
> So instead of GFP_NOIO use GFP_KERNEL and do all the memory allocation
> in blkfront_setup_indirect() in a memalloc_noio_{save,restore} section.
>
> Fixes: 1d5c76e664333 ("xen-blkfront: switch kcalloc to kvcalloc for large array allocation")
> Cc: [e-mail]
> Signed-off-by: Juergen Gross <[e-mail]>

Reviewed-by: Boris Ostrovsky <[e-mail]>

Roger Pau Monné April 6, 2020, 9:02 a.m. UTC | #2

On Fri, Apr 03, 2020 at 11:00:34AM +0200, Juergen Gross wrote:
> Commit 1d5c76e664333 ("xen-blkfront: switch kcalloc to kvcalloc for
> large array allocation") didn't fix the issue it was meant to, as the
> flags for allocating the memory are GFP_NOIO, which will lead the
> memory allocation falling back to kmalloc().
> 
> So instead of GFP_NOIO use GFP_KERNEL and do all the memory allocation
> in blkfront_setup_indirect() in a memalloc_noio_{save,restore} section.
> 
> Fixes: 1d5c76e664333 ("xen-blkfront: switch kcalloc to kvcalloc for large array allocation")
> Cc: [e-mail]
> Signed-off-by: Juergen Gross <[e-mail]>

Acked-by: Roger Pau Monné <[e-mail]>

Thanks!

Patch

diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
index 915cf5b6388c..3b889ea950c2 100644
--- a/drivers/block/xen-blkfront.c
+++ b/drivers/block/xen-blkfront.c
@@ -47,6 +47,7 @@ 
 #include <linux/bitmap.h>
 #include <linux/list.h>
 #include <linux/workqueue.h>
+#include <linux/sched/mm.h>
 
 #include <xen/xen.h>
 #include <xen/xenbus.h>
@@ -2189,10 +2190,12 @@  static void blkfront_setup_discard(struct blkfront_info *info)
 
 static int blkfront_setup_indirect(struct blkfront_ring_info *rinfo)
 {
-	unsigned int psegs, grants;
+	unsigned int psegs, grants, memflags;
 	int err, i;
 	struct blkfront_info *info = rinfo->dev_info;
 
+	memflags = memalloc_noio_save();
+
 	if (info->max_indirect_segments == 0) {
 		if (!HAS_EXTRA_REQ)
 			grants = BLKIF_MAX_SEGMENTS_PER_REQUEST;
@@ -2224,7 +2227,7 @@  static int blkfront_setup_indirect(struct blkfront_ring_info *rinfo)
 
 		BUG_ON(!list_empty(&rinfo->indirect_pages));
 		for (i = 0; i < num; i++) {
-			struct page *indirect_page = alloc_page(GFP_NOIO);
+			struct page *indirect_page = alloc_page(GFP_KERNEL);
 			if (!indirect_page)
 				goto out_of_memory;
 			list_add(&indirect_page->lru, &rinfo->indirect_pages);
@@ -2235,15 +2238,15 @@  static int blkfront_setup_indirect(struct blkfront_ring_info *rinfo)
 		rinfo->shadow[i].grants_used =
 			kvcalloc(grants,
 				 sizeof(rinfo->shadow[i].grants_used[0]),
-				 GFP_NOIO);
+				 GFP_KERNEL);
 		rinfo->shadow[i].sg = kvcalloc(psegs,
 					       sizeof(rinfo->shadow[i].sg[0]),
-					       GFP_NOIO);
+					       GFP_KERNEL);
 		if (info->max_indirect_segments)
 			rinfo->shadow[i].indirect_grants =
 				kvcalloc(INDIRECT_GREFS(grants),
 					 sizeof(rinfo->shadow[i].indirect_grants[0]),
-					 GFP_NOIO);
+					 GFP_KERNEL);
 		if ((rinfo->shadow[i].grants_used == NULL) ||
 			(rinfo->shadow[i].sg == NULL) ||
 		     (info->max_indirect_segments &&
@@ -2252,6 +2255,7 @@  static int blkfront_setup_indirect(struct blkfront_ring_info *rinfo)
 		sg_init_table(rinfo->shadow[i].sg, psegs);
 	}
 
+	memalloc_noio_restore(memflags);
 
 	return 0;
 
@@ -2271,6 +2275,9 @@  static int blkfront_setup_indirect(struct blkfront_ring_info *rinfo)
 			__free_page(indirect_page);
 		}
 	}
+
+	memalloc_noio_restore(memflags);
+
 	return -ENOMEM;
 }