netdevsim: use __GFP_NOWARN to avoid memalloc warning

vfnum buffer size and binary_len buffer size is received by user-space.
So, this buffer size could be too large. If so, kmalloc will internally
print a warning message.
This warning message is actually not necessary for the netdevsim module.
So, this patch adds __GFP_NOWARN.

Test commands:
    modprobe netdevsim
    echo 1 > /sys/bus/netdevsim/new_device
    echo 1000000000 > /sys/devices/netdevsim1/sriov_numvfs

Splat looks like:
[  357.847266][ T1000] WARNING: CPU: 0 PID: 1000 at mm/page_alloc.c:4738 __alloc_pages_nodemask+0x2f3/0x740
[  357.850273][ T1000] Modules linked in: netdevsim veth openvswitch nsh nf_conncount nf_nat nf_conntrack nf_defrx
[  357.852989][ T1000] CPU: 0 PID: 1000 Comm: bash Tainted: G    B             5.5.0-rc5+ #270
[  357.854334][ T1000] Hardware name: innotek GmbH VirtualBox/VirtualBox, BIOS VirtualBox 12/01/2006
[  357.855703][ T1000] RIP: 0010:__alloc_pages_nodemask+0x2f3/0x740
[  357.856669][ T1000] Code: 64 fe ff ff 65 48 8b 04 25 c0 0f 02 00 48 05 f0 12 00 00 41 be 01 00 00 00 49 89 47 0
[  357.860272][ T1000] RSP: 0018:ffff8880b7f47bd8 EFLAGS: 00010246
[  357.861009][ T1000] RAX: ffffed1016fe8f80 RBX: 1ffff11016fe8fae RCX: 0000000000000000
[  357.861843][ T1000] RDX: 0000000000000000 RSI: 0000000000000017 RDI: 0000000000000000
[  357.862661][ T1000] RBP: 0000000000040dc0 R08: 1ffff11016fe8f67 R09: dffffc0000000000
[  357.863509][ T1000] R10: ffff8880b7f47d68 R11: fffffbfff2798180 R12: 1ffff11016fe8f80
[  357.864355][ T1000] R13: 0000000000000017 R14: 0000000000000017 R15: ffff8880c2038d68
[  357.865178][ T1000] FS:  00007fd9a5b8c740(0000) GS:ffff8880d9c00000(0000) knlGS:0000000000000000
[  357.866248][ T1000] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  357.867531][ T1000] CR2: 000055ce01ba8100 CR3: 00000000b7dbe005 CR4: 00000000000606f0
[  357.868972][ T1000] Call Trace:
[  357.869423][ T1000]  ? lock_contended+0xcd0/0xcd0
[  357.870001][ T1000]  ? __alloc_pages_slowpath+0x21d0/0x21d0
[  357.870673][ T1000]  ? _kstrtoull+0x76/0x160
[  357.871148][ T1000]  ? alloc_pages_current+0xc1/0x1a0
[  357.871704][ T1000]  kmalloc_order+0x22/0x80
[  357.872184][ T1000]  kmalloc_order_trace+0x1d/0x140
[  357.872733][ T1000]  __kmalloc+0x302/0x3a0
[  357.873204][ T1000]  nsim_bus_dev_numvfs_store+0x1ab/0x260 [netdevsim]
[  357.873919][ T1000]  ? kernfs_get_active+0x12c/0x180
[  357.874459][ T1000]  ? new_device_store+0x450/0x450 [netdevsim]
[  357.875111][ T1000]  ? kernfs_get_parent+0x70/0x70
[  357.875632][ T1000]  ? sysfs_file_ops+0x160/0x160
[  357.876152][ T1000]  kernfs_fop_write+0x276/0x410
[  357.876680][ T1000]  ? __sb_start_write+0x1ba/0x2e0
[  357.877225][ T1000]  vfs_write+0x197/0x4a0
[  357.877671][ T1000]  ksys_write+0x141/0x1d0
[ ... ]
Reviewed-by: Jakub Kicinski <kuba@kernel.org>
Fixes: 79579220 ("netdevsim: add SR-IOV functionality")
Fixes: 82c93a87 ("netdevsim: implement couple of testing devlink health reporters")
Signed-off-by: Taehee Yoo <ap420073@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/netdevsim/bus.c

@@ -29,7 +29,7 @@ static int nsim_bus_dev_vfs_enable(struct nsim_bus_dev *nsim_bus_dev,
 {
 	nsim_bus_dev->vfconfigs = kcalloc(num_vfs,
 					  sizeof(struct nsim_vf_config),
-					  GFP_KERNEL);
+					  GFP_KERNEL | __GFP_NOWARN);
 	if (!nsim_bus_dev->vfconfigs)
 		return -ENOMEM;
 	nsim_bus_dev->num_vfs = num_vfs;

drivers/net/netdevsim/health.c

@@ -82,7 +82,7 @@ static int nsim_dev_dummy_fmsg_put(struct devlink_fmsg *fmsg, u32 binary_len)
 	if (err)
 		return err;
 
-	binary = kmalloc(binary_len, GFP_KERNEL);
+	binary = kmalloc(binary_len, GFP_KERNEL | __GFP_NOWARN);
 	if (!binary)
 		return -ENOMEM;
 	get_random_bytes(binary, binary_len);