From: Mikulas Patocka <[email-masked]>

Set noio flag while calling __vmalloc() because it doesn't fully respect
gfp flags to avoid a possible deadlock (see commit
502624bdad3dba45dfaacaf36b7d83e39e74b2d2).

This should be backported to stable kernels 3.8 and newer. The kernel 3.8
doesn't have memalloc_noio_save(), so we should set and restore process
flag PF_MEMALLOC instead.

Signed-off-by: Mikulas Patocka <[email-masked]>
Cc: [email-masked]
Signed-off-by: Alasdair G Kergon <[email-masked]>

---
 drivers/md/dm-ioctl.c |    3 +++
 1 file changed, 3 insertions(+)

Index: linux/drivers/md/dm-ioctl.c
===================================================================
--- linux.orig/drivers/md/dm-ioctl.c
+++ linux/drivers/md/dm-ioctl.c
@@ -1644,7 +1644,10 @@ static int copy_params(struct dm_ioctl _
 	}
 
 	if (!dmi) {
+		unsigned noio_flag;
+		noio_flag = memalloc_noio_save();
 		dmi = __vmalloc(param_kernel->data_size, GFP_NOIO | __GFP_REPEAT | __GFP_HIGH, PAGE_KERNEL);
+		memalloc_noio_restore(noio_flag);
 		if (dmi)
 			*param_flags |= DM_PARAMS_VMALLOC;
 	}