lkml.org 
[lkml]   [2017]   [Nov]   [28]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 4.9 021/138] dm: allocate struct mapped_device with kvzalloc
Date
4.9-stable review patch.  If anyone has any objections, please let me know.

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

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)

\
 
 \ /
  Last update: 2017-11-28 13:03    [W:0.317 / U:2.500 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site