[PATCH] dm persistent data: fix memory allocation failure

[PATCH] dm persistent data: fix memory allocation failure

[Mikulas Patocka]

kmalloc is unreliable when allocating more than 8 pages of memory. It may
fail when there is plenty of free memory but the memory is fragmented.
Zdenek Kabelac observed such failure in his tests.

This commit changes kmalloc to kvmalloc - kvmalloc will fall back to
vmalloc if the large allocation fails.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Cc: stable@vger.kernel.org

---
 drivers/md/persistent-data/dm-space-map-metadata.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

Index: linux-2.6/drivers/md/persistent-data/dm-space-map-metadata.c
===================================================================
--- linux-2.6.orig/drivers/md/persistent-data/dm-space-map-metadata.c	2024-08-13 13:25:04.000000000 +0200
+++ linux-2.6/drivers/md/persistent-data/dm-space-map-metadata.c	2024-08-13 14:39:08.000000000 +0200
@@ -277,7 +277,7 @@ static void sm_metadata_destroy(struct d
 {
 	struct sm_metadata *smm = container_of(sm, struct sm_metadata, sm);
 
-	kfree(smm);
+	kvfree(smm);
 }
 
 static int sm_metadata_get_nr_blocks(struct dm_space_map *sm, dm_block_t *count)
@@ -772,7 +772,7 @@ struct dm_space_map *dm_sm_metadata_init
 {
 	struct sm_metadata *smm;
 
-	smm = kmalloc(sizeof(*smm), GFP_KERNEL);
+	smm = kvmalloc(sizeof(*smm), GFP_KERNEL);
 	if (!smm)
 		return ERR_PTR(-ENOMEM);
 

Re: dm persistent data: fix memory allocation failure

[Mike Snitzer]

On Tue, Aug 13, 2024 at 04:35:14PM +0200, Mikulas Patocka wrote:
> kmalloc is unreliable when allocating more than 8 pages of memory. It may
> fail when there is plenty of free memory but the memory is fragmented.
> Zdenek Kabelac observed such failure in his tests.
> 
> This commit changes kmalloc to kvmalloc - kvmalloc will fall back to
> vmalloc if the large allocation fails.

Should add this tag here:
Reported-by: Zdenek Kabelac <zkabelac@redhat.com>
 
> Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
> Cc: stable@vger.kernel.org

Reviewed-by: Mike Snitzer <snitzer@kernel.org>