linux-kernel - [PATCH 8/9] md: use kvmalloc rather than opencoded variant

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Date:   Mon,  6 Mar 2017 11:33:26 +0100
From:   Michal Hocko <mhocko@...nel.org>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     <linux-mm@...ck.org>, LKML <linux-kernel@...r.kernel.org>,
        Michal Hocko <mhocko@...e.com>,
        Mike Snitzer <snitzer@...hat.com>,
        Mikulas Patocka <mpatocka@...hat.com>,
        Vlastimil Babka <vbabka@...e.cz>
Subject: [PATCH 8/9] md: use kvmalloc rather than opencoded variant

From: Michal Hocko <mhocko@...e.com>

copy_params uses kmalloc with vmalloc fallback. We already have a helper
for that - kvmalloc. This caller requires GFP_NOIO semantic so it hasn't
been converted with many others by previous patches. All we need to
achieve this semantic is to use the scope memalloc_noio_{save,restore}
around kvmalloc.

Cc: Mikulas Patocka <mpatocka@...hat.com>
Cc: Mike Snitzer <snitzer@...hat.com>
Acked-by: Vlastimil Babka <vbabka@...e.cz>
Signed-off-by: Michal Hocko <mhocko@...e.com>
---
 drivers/md/dm-ioctl.c | 13 ++++---------
 1 file changed, 4 insertions(+), 9 deletions(-)

diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c
index 4da6fc6b1ffd..4951bf99dfb1 100644
--- a/drivers/md/dm-ioctl.c
+++ b/drivers/md/dm-ioctl.c
@@ -1699,6 +1699,7 @@ static int copy_params(struct dm_ioctl __user *user, struct dm_ioctl *param_kern
 	struct dm_ioctl *dmi;
 	int secure_data;
 	const size_t minimum_data_size = offsetof(struct dm_ioctl, data);
+	unsigned noio_flag;
 
 	if (copy_from_user(param_kernel, user, minimum_data_size))
 		return -EFAULT;
@@ -1721,15 +1722,9 @@ static int copy_params(struct dm_ioctl __user *user, struct dm_ioctl *param_kern
 	 * Use kmalloc() rather than vmalloc() when we can.
 	 */
 	dmi = NULL;
-	if (param_kernel->data_size <= KMALLOC_MAX_SIZE)
-		dmi = kmalloc(param_kernel->data_size, GFP_NOIO | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN);
-
-	if (!dmi) {
-		unsigned noio_flag;
-		noio_flag = memalloc_noio_save();
-		dmi = __vmalloc(param_kernel->data_size, GFP_NOIO | __GFP_HIGH | __GFP_HIGHMEM, PAGE_KERNEL);
-		memalloc_noio_restore(noio_flag);
-	}
+	noio_flag = memalloc_noio_save();
+	dmi = kvmalloc(param_kernel->data_size, GFP_KERNEL);
+	memalloc_noio_restore(noio_flag);
 
 	if (!dmi) {
 		if (secure_data && clear_user(user, param_kernel->data_size))
-- 
2.11.0