[media] videobuf2-dma-sg: fix for wrong GFP mask to sg_alloc_table_from_pages

sg_alloc_table_from_pages() only allocates a sg_table, so it should just use
GFP_KERNEL, not gfp_flags. If gfp_flags contains __GFP_DMA32 then mm/sl[au]b.c
will call BUG_ON:

[  358.027515] ------------[ cut here ]------------
[  358.027546] kernel BUG at mm/slub.c:1416!
[  358.027558] invalid opcode: 0000 [#1] PREEMPT SMP
[  358.027576] Modules linked in: mt2131 s5h1409 tda8290 tuner cx25840 cx23885 btcx_risc altera_ci tda18271 altera_stapl videobuf2_dvb tveeprom cx2341x videobuf2_dma_sg dvb_core rc_core videobuf2_memops videobuf2_core nouveau zr36067 videocodec v4l2_common videodev media x86_pkg_temp_thermal cfbfillrect cfbimgblt cfbcopyarea ttm drm_kms_helper processor button isci
[  358.027712] CPU: 19 PID: 3654 Comm: cat Not tainted 3.16.0-rc6-telek #167
[  358.027723] Hardware name: ASUSTeK COMPUTER INC. Z9PE-D8 WS/Z9PE-D8 WS, BIOS 5404 02/10/2014
[  358.027741] task: ffff880897c7d960 ti: ffff88089b4d4000 task.ti: ffff88089b4d4000
[  358.027753] RIP: 0010:[<ffffffff81196040>]  [<ffffffff81196040>] new_slab+0x280/0x320
[  358.027776] RSP: 0018:ffff88089b4d7ae8  EFLAGS: 00010002
[  358.027787] RAX: ffff880897c7d960 RBX: 0000000000000000 RCX: ffff88089b4d7b50
[  358.027798] RDX: 00000000ffffffff RSI: 0000000000000004 RDI: ffff88089f803b00
[  358.027809] RBP: ffff88089b4d7bb8 R08: 0000000000000000 R09: 0000000100400040
[  358.027821] R10: 0000160000000000 R11: ffff88109bc02c40 R12: 0000000000000001
[  358.027832] R13: ffff88089f8000c0 R14: ffff88089f803b00 R15: ffff8810bfcf4be0
[  358.027845] FS:  00007f83fe5c0700(0000) GS:ffff8810bfce0000(0000) knlGS:0000000000000000
[  358.027858] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  358.027868] CR2: 0000000001dfd568 CR3: 0000001097d5a000 CR4: 00000000000407e0
[  358.027878] Stack:
[  358.027885]  ffffffff81198860 ffff8810bfcf4be0 ffff880897c7d960 0000000000001b00
[  358.027905]  ffff880897c7d960 0000000000000000 ffff8810bfcf4bf0 0000000000000000
[  358.027924]  0000000000000000 0000000100000100 ffffffff813ef84a 00000004ffffffff
[  358.027944] Call Trace:
[  358.027956]  [<ffffffff81198860>] ? __slab_alloc+0x400/0x4e0
[  358.027973]  [<ffffffff813ef84a>] ? sg_kmalloc+0x1a/0x30
[  358.027985]  [<ffffffff81198f17>] __kmalloc+0x127/0x150
[  358.027997]  [<ffffffff813ef84a>] ? sg_kmalloc+0x1a/0x30
[  358.028009]  [<ffffffff813ef84a>] sg_kmalloc+0x1a/0x30
[  358.028023]  [<ffffffff813eff84>] __sg_alloc_table+0x74/0x180
[  358.028035]  [<ffffffff813ef830>] ? sg_kfree+0x20/0x20
[  358.028048]  [<ffffffff813f00af>] sg_alloc_table+0x1f/0x60
[  358.028061]  [<ffffffff813f0174>] sg_alloc_table_from_pages+0x84/0x1f0
[  358.028077]  [<ffffffffa007c3f9>] vb2_dma_sg_alloc+0x159/0x230 [videobuf2_dma_sg]
[  358.028095]  [<ffffffffa003d55a>] __vb2_queue_alloc+0x10a/0x680 [videobuf2_core]
[  358.028113]  [<ffffffffa003e110>] __reqbufs.isra.14+0x220/0x3e0 [videobuf2_core]
[  358.028130]  [<ffffffffa003e79d>] __vb2_init_fileio+0xbd/0x380 [videobuf2_core]
[  358.028147]  [<ffffffffa003f563>] __vb2_perform_fileio+0x5b3/0x6e0 [videobuf2_core]
[  358.028164]  [<ffffffffa003f871>] vb2_fop_read+0xb1/0x100 [videobuf2_core]
[  358.028184]  [<ffffffffa06dd2e5>] v4l2_read+0x65/0xb0 [videodev]
[  358.028198]  [<ffffffff811a243f>] vfs_read+0x8f/0x170
[  358.028210]  [<ffffffff811a30a1>] SyS_read+0x41/0xb0
[  358.028224]  [<ffffffff818f02e9>] system_call_fastpath+0x16/0x1b
[  358.028234] Code: 66 90 e9 dc fd ff ff 0f 1f 40 00 41 8b 4d 68 e9 d5 fe ff ff 0f 1f 80 00 00 00 00 f0 41 80 4d 00 40 e9 03 ff ff ff 0f 1f 44 00 00 <0f> 0b 66 0f 1f 44 00 00 44 89 c6 4c 89 45 d0 e8 0c 82 ff ff 48
[  358.028415] RIP  [<ffffffff81196040>] new_slab+0x280/0x320
[  358.028432]  RSP <ffff88089b4d7ae8>
[  358.032208] ---[ end trace 6443240199c706e4 ]---
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Cc: stable@vger.kernel.org      # for v3.13 and up
Acked-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>

drivers/media/v4l2-core/videobuf2-dma-sg.c

@@ -113,7 +113,7 @@ static void *vb2_dma_sg_alloc(void *alloc_ctx, unsigned long size, gfp_t gfp_fla
 		goto fail_pages_alloc;
 
 	ret = sg_alloc_table_from_pages(&buf->sg_table, buf->pages,
-			buf->num_pages, 0, size, gfp_flags);
+			buf->num_pages, 0, size, GFP_KERNEL);
 	if (ret)
 		goto fail_table_alloc;