Commit 1c0e883e authored Jul 10, 2013 by Mikulas Patocka Committed by Alasdair G Kergon Jul 10, 2013

dm ioctl: set noio flag to avoid __vmalloc deadlock



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

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 <mpatocka@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Alasdair G Kergon <agk@redhat.com>

parent 6c182cd8

drivers/md/dm-ioctl.c

+3 −0

Original line number	Diff line number	Diff line
		@@ -1644,7 +1644,10 @@ static int copy_params(struct dm_ioctl __user user, struct dm_ioctl param_kern
		}

		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;
		}