This is a note to let you know that I've just added the patch titled
dm: allocate buffer for messages with small number of arguments using GFP_NOIO
to the 3.4-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:
dm-allocate-buffer-for-messages-with-small-number-of-arguments-using-gfp_noio.patch
and it can be found in the queue-3.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From f36afb3957353d2529cb2b00f78fdccd14fc5e9c Mon Sep 17 00:00:00 2001
From: Mikulas Patocka <mpatocka@xxxxxxxxxx>
Date: Thu, 31 Oct 2013 13:55:45 -0400
Subject: dm: allocate buffer for messages with small number of arguments using GFP_NOIO
From: Mikulas Patocka <mpatocka@xxxxxxxxxx>
commit f36afb3957353d2529cb2b00f78fdccd14fc5e9c upstream.
dm-mpath and dm-thin must process messages even if some device is
suspended, so we allocate argv buffer with GFP_NOIO. These messages have
a small fixed number of arguments.
On the other hand, dm-switch needs to process bulk data using messages
so excessive use of GFP_NOIO could cause trouble.
The patch also lowers the default number of arguments from 64 to 8, so
that there is smaller load on GFP_NOIO allocations.
Signed-off-by: Mikulas Patocka <mpatocka@xxxxxxxxxx>
Acked-by: Alasdair G Kergon <agk@xxxxxxxxxx>
Signed-off-by: Mike Snitzer <snitzer@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/md/dm-table.c | 18 ++++++++++++++++--
1 file changed, 16 insertions(+), 2 deletions(-)
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -581,14 +581,28 @@ static int adjoin(struct dm_table *table
/*
* Used to dynamically allocate the arg array.
+ *
+ * We do first allocation with GFP_NOIO because dm-mpath and dm-thin must
+ * process messages even if some device is suspended. These messages have a
+ * small fixed number of arguments.
+ *
+ * On the other hand, dm-switch needs to process bulk data using messages and
+ * excessive use of GFP_NOIO could cause trouble.
*/
static char **realloc_argv(unsigned *array_size, char **old_argv)
{
char **argv;
unsigned new_size;
+ gfp_t gfp;
- new_size = *array_size ? *array_size * 2 : 64;
- argv = kmalloc(new_size * sizeof(*argv), GFP_KERNEL);
+ if (*array_size) {
+ new_size = *array_size * 2;
+ gfp = GFP_KERNEL;
+ } else {
+ new_size = 8;
+ gfp = GFP_NOIO;
+ }
+ argv = kmalloc(new_size * sizeof(*argv), gfp);
if (argv) {
memcpy(argv, old_argv, *array_size * sizeof(*argv));
*array_size = new_size;
Patches currently in stable-queue which might be from mpatocka@xxxxxxxxxx are
queue-3.4/dm-allocate-buffer-for-messages-with-small-number-of-arguments-using-gfp_noio.patch
queue-3.4/loop-fix-crash-if-blk_alloc_queue-fails.patch
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