This is a note to let you know that I've just added the patch titled
dm: allocate struct mapped_device with kvzalloc
to the 4.9-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...
The filename of the patch is: dm-allocate-struct-mapped_device-with-kvzalloc.patch and it can be found in the queue-4.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.
From 856eb0916d181da6d043cc33e03f54d5c5bbe54a Mon Sep 17 00:00:00 2001
From: Mikulas Patocka mpatocka@redhat.com Date: Tue, 31 Oct 2017 19:33:02 -0400 Subject: dm: allocate struct mapped_device with kvzalloc
From: Mikulas Patocka mpatocka@redhat.com
commit 856eb0916d181da6d043cc33e03f54d5c5bbe54a upstream.
The structure srcu_struct can be very big, its size is proportional to the value CONFIG_NR_CPUS. The Fedora kernel has CONFIG_NR_CPUS 8192, the field io_barrier in the struct mapped_device has 84kB in the debugging kernel and 50kB in the non-debugging kernel. The large size may result in failure of the function kzalloc_node.
In order to avoid the allocation failure, we use the function kvzalloc_node, this function falls back to vmalloc if a large contiguous chunk of memory is not available. This patch also moves the field io_barrier to the last position of struct mapped_device - the reason is that on many processor architectures, short memory offsets result in smaller code than long memory offsets - on x86-64 it reduces code size by 320 bytes.
Note to stable kernel maintainers - the kernels 4.11 and older don't have the function kvzalloc_node, you can use the function vzalloc_node instead.
Signed-off-by: Mikulas Patocka mpatocka@redhat.com Signed-off-by: Mike Snitzer snitzer@redhat.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/md/dm-core.h | 3 ++- drivers/md/dm.c | 7 ++++--- 2 files changed, 6 insertions(+), 4 deletions(-)
--- a/drivers/md/dm-core.h +++ b/drivers/md/dm-core.h @@ -29,7 +29,6 @@ struct dm_kobject_holder { * DM targets must _not_ deference a mapped_device to directly access its members! */ struct mapped_device { - struct srcu_struct io_barrier; struct mutex suspend_lock;
/* @@ -127,6 +126,8 @@ struct mapped_device { struct blk_mq_tag_set *tag_set; bool use_blk_mq:1; bool init_tio_pdu:1; + + struct srcu_struct io_barrier; };
void dm_init_md_queue(struct mapped_device *md); --- a/drivers/md/dm.c +++ b/drivers/md/dm.c @@ -21,6 +21,7 @@ #include <linux/delay.h> #include <linux/wait.h> #include <linux/pr.h> +#include <linux/vmalloc.h>
#define DM_MSG_PREFIX "core"
@@ -1511,7 +1512,7 @@ static struct mapped_device *alloc_dev(i struct mapped_device *md; void *old_md;
- md = kzalloc_node(sizeof(*md), GFP_KERNEL, numa_node_id); + md = vzalloc_node(sizeof(*md), numa_node_id); if (!md) { DMWARN("unable to allocate device, out of memory."); return NULL; @@ -1605,7 +1606,7 @@ bad_io_barrier: bad_minor: module_put(THIS_MODULE); bad_module_get: - kfree(md); + kvfree(md); return NULL; }
@@ -1624,7 +1625,7 @@ static void free_dev(struct mapped_devic free_minor(minor);
module_put(THIS_MODULE); - kfree(md); + kvfree(md); }
static void __bind_mempools(struct mapped_device *md, struct dm_table *t)
Patches currently in stable-queue which might be from mpatocka@redhat.com are
queue-4.9/dm-allocate-struct-mapped_device-with-kvzalloc.patch