[PATCH 1/2] vhost-scsi: use kvzalloc for vq array allocation

[Dongli Zhang <dongli.zhang@oracle.com>]

vhost_scsi_open() allocates one "struct vhost_scsi_virtqueue" for each
virtqueue. With large max_io_vqs values, this array can require a
high-order contiguous allocation and trigger a page allocator warning.

hv# cat /sys/module/vhost_scsi/parameters/max_io_vqs
256

[  766.075787] ------------[ cut here ]------------
[  766.077030] WARNING: mm/page_alloc.c:5280 at __alloc_frozen_pages_noprof+0x32c/0x15c0, CPU#23: qemu-system-x86/5964
... ...
[  766.080351] RIP: 0010:__alloc_frozen_pages_noprof+0x32c/0x15c0
... ...
[  766.085813] Call Trace:
[  766.085969]  <TASK>
[  766.086098]  ? srso_alias_return_thunk+0x5/0xfbef5
[  766.086365]  ? context_struct_compute_av+0x38a/0x4b0
[  766.086652]  alloc_pages_mpol+0x9f/0x170
[  766.086883]  ___kmalloc_large_node+0xb6/0xd0
[  766.087124]  ? srso_alias_return_thunk+0x5/0xfbef5
[  766.087389]  __kmalloc_large_node_noprof+0x18/0xa0
[  766.087655]  __kmalloc_noprof+0x3a0/0x440
[  766.087877]  ? vhost_scsi_open+0xcb/0x2d0 [vhost_scsi]
[  766.088162]  vhost_scsi_open+0xcb/0x2d0 [vhost_scsi]
[  766.088449]  misc_open+0x123/0x160
[  766.088679]  chrdev_open+0xb1/0x230
[  766.088885]  ? __pfx_chrdev_open+0x10/0x10
[  766.089157]  do_dentry_open+0x11a/0x470
[  766.089389]  vfs_open+0x29/0xf0
[  766.089596]  path_openat+0x7c0/0x1100
[  766.089821]  do_file_open+0xdd/0x190
[  766.090032]  ? srso_alias_return_thunk+0x5/0xfbef5
[  766.090332]  do_sys_openat2+0x7e/0x100
[  766.090601]  __x64_sys_openat+0x51/0xa0
[  766.090857]  do_syscall_64+0xfe/0x590
[  766.091087]  entry_SYSCALL_64_after_hwframe+0x77/0x7f
[  766.091411] RIP: 0033:0x7f9525a11fa6

The array does not require physical contiguity, so allocate it with
kvzalloc_objs() and free it with kvfree().

Signed-off-by: Dongli Zhang <dongli.zhang@oracle.com>
---
 drivers/vhost/scsi.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/vhost/scsi.c b/drivers/vhost/scsi.c
index 9a1253b9d8c5..0c0634eea144 100644
--- a/drivers/vhost/scsi.c
+++ b/drivers/vhost/scsi.c
@@ -2295,7 +2295,7 @@ static int vhost_scsi_open(struct inode *inode, struct file *f)
 	if (!vs->old_inflight)
 		goto err_inflight;
 
-	vs->vqs = kmalloc_objs(*vs->vqs, nvqs, GFP_KERNEL | __GFP_ZERO);
+	vs->vqs = kvzalloc_objs(*vs->vqs, nvqs);
 	if (!vs->vqs)
 		goto err_vqs;
 
@@ -2331,7 +2331,7 @@ static int vhost_scsi_open(struct inode *inode, struct file *f)
 	return 0;
 
 err_local_vqs:
-	kfree(vs->vqs);
+	kvfree(vs->vqs);
 err_vqs:
 	kfree(vs->old_inflight);
 err_inflight:
@@ -2352,7 +2352,7 @@ static int vhost_scsi_release(struct inode *inode, struct file *f)
 	vhost_dev_stop(&vs->dev);
 	vhost_dev_cleanup(&vs->dev);
 	kfree(vs->dev.vqs);
-	kfree(vs->vqs);
+	kvfree(vs->vqs);
 	kfree(vs->old_inflight);
 	kvfree(vs);
 	return 0;
-- 
2.43.5