On 22/06/12 05:39, Prabhakar Lad wrote:
Hi Federico,
Recent patch from you (commit id a8f3c203e19b702fa5e8e83a9b6fb3c5a6d1cce4) which
added cached buffer support to videobuf dma contig, is causing my
driver to crash.
Has this patch being tested for 'uncached' buffers ? If I replace this
mapping logic with
remap_pfn_range() my driver works without any crash.
Or is that I am missing somewhere ?
No, I had the same problem this week with vpif_capture. Since I was running an
unusual setup (a 3.0 kernel with the media subsystem patched to 3.5-rc1) I didn't
know whether it was caused by a mismatch between 3.0 and a 3.5 media subsystem.
I intended to investigate this next week, but now it is clear that it is this patch
that is causing the problem.
Here is our trace:
Unable to handle kernel paging request at virtual address d5ffdf51
pgd = c2ae8000
[d5ffdf51] *pgd=00000000
Internal error: Oops: 1 [#1] PREEMPT
CPU: 0 Not tainted (3.0.31-jqiang #1)
PC is at vm_insert_page+0x34/0x5c
LR is at __videobuf_mmap_mapper+0xf0/0x1f4
pc : [<c00c1494>] lr : [<c0215d2c>] psr: 00000013
sp : c5589ed0 ip : 00000000 fp : c5587628
r10: c046bc54 r9 : c2a44dc0 r8 : 0011e000
r7 : bfc01000 r6 : c5591fc4 r5 : c2afbee8 r4 : 424d5000
r3 : c2afbee8 r2 : c0c6f000 r1 : 424d5000 r0 : d5ffdf4d
Flags: nzcv IRQs on FIQs on Mode SVC_32 ISA ARM Segment user
Control: 0005317f Table: 82ae8000 DAC: 00000015
Process Video (pid: 1230, stack limit = 0xc5588270)
Stack: (0xc5589ed0 to 0xc558a000)
9ec0: c0215c3c c5587628 c2afbee8 424d5000
9ee0: c564a200 0011e000 0000011e c2afbee8 c5588000 c0213620 c55bf400 c2b416e0
9f00: 424d5000 c02020f4 c2b44a90 424d5000 c564a200 c2b44a8c c2b44a90 c00c6524
9f20: 000000ff 00000000 c2b416e0 00000000 00000000 c5588000 0011e000 c2b44a70
9f40: c2b416e0 00000000 c759fa70 00000001 00000000 425f3000 c7960000 00000001
9f60: c5588000 c2b416e0 00000003 0011df00 c5588000 00000000 00592d2c c00c6ad4
9f80: 000000ff 00000000 00592d2c 00000021 00000000 00000021 000000c0 c002bc48
9fa0: 00000000 c002baa0 00000021 00000000 00000000 0011df00 00000003 00000001
9fc0: 00000021 00000000 00000021 000000c0 00000001 00592ca4 000a2aa0 00592d2c
9fe0: 00000000 00592b68 00023ce8 403318d8 40000010 00000000 00000000 00000000
[<c00c1494>] (vm_insert_page+0x34/0x5c) from [<c0215d2c>]
(__videobuf_mmap_mapper+0xf0/0x1f4)
[<c0215d2c>] (__videobuf_mmap_mapper+0xf0/0x1f4) from [<c0213620>]
(videobuf_mmap_mapper+0xa0/0x128)
[<c0213620>] (videobuf_mmap_mapper+0xa0/0x128) from [<c02020f4>]
(v4l2_mmap+0x88/0xb8)
[<c02020f4>] (v4l2_mmap+0x88/0xb8) from [<c00c6524>]
(mmap_region+0x340/0x530)
[<c00c6524>] (mmap_region+0x340/0x530) from [<c00c6ad4>]
(sys_mmap_pgoff+0x7c/0xbc)
[<c00c6ad4>] (sys_mmap_pgoff+0x7c/0xbc) from [<c002baa0>]
(ret_fast_syscall+0x0/0x2c)
Code: e5920000 e3100902 1592000c 01a00002 (e5900004)
---[ end trace 907d90a82cfa0ada ]---
I've traced the bug to the fact that the page returned by:
page = virt_to_page((void *)pos);
does not have a valid page->first_page pointer, causing page_count() to fail.
As far as I can tell from reading the diff the remap_pfn_range() was just dropped,
presumably by accident.
This (untested!) patch restores it:
diff --git a/drivers/media/video/videobuf-dma-contig.c b/drivers/media/video/videobuf-dma-contig.c
index b6b5cc1..75efd8f 100644
--- a/drivers/media/video/videobuf-dma-contig.c
+++ b/drivers/media/video/videobuf-dma-contig.c
@@ -359,8 +359,17 @@ static int __videobuf_mmap_mapper(struct videobuf_queue *q,
size = vma->vm_end - vma->vm_start;
size = (size < mem->size) ? size : mem->size;
- if (!mem->cached)
+ if (!mem->cached) {
vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
+ retval = remap_pfn_range(vma, vma->vm_start,
+ mem->dma_handle >> PAGE_SHIFT,
+ size, vma->vm_page_prot);
+ if (retval) {
+ dev_err(q->dev, "mmap: remap failed with error %d.\n", retval);
+ __videobuf_dc_free(q->dev, mem);
+ goto error;
+ }
+ }
pos = (unsigned long)mem->vaddr;
I'll test this next week.
Regards,
Hans
------
Thx,
--Prabhakar
Following is the crash log:
Unable to handle kernel paging request at virtual address e1a0201a
pgd = c372c000
[e1a0201a] *pgd=00000000
Internal error: Oops: 1 [#1] PREEMPT ARM
Modules linked in:
CPU: 0 Not tainted (3.5.0-rc3+ #32)
PC is at flush_dcache_page+0x4c/0x1b8
LR is at insert_page+0x38/0x158
pc : [<c000f028>] lr : [<c0075b58>] psr: a0000013
sp : c36d5d90 ip : c36d5dd8 fp : c36d5dd4
r10: c5000000 r9 : 00000000 r8 : 00281000
r7 : 00000103 r6 : c2d60780 r5 : e1a02006 r4 : c056f000
r3 : 00000000 r2 : e1a02006 r1 : b6bb8000 r0 : c056f000
Flags: NzCv IRQs on FIQs on Mode SVC_32 ISA ARM Segment user
Control: 0005317f Table: c372c000 DAC: 00000015
Process vpif_display (pid: 1167, stack limit = 0xc36d4270)
Stack: (0xc36d5d90 to 0xc36d6000)
5d80: 00000000 00000000 c36d5de4 c36d5da8
5da0: c0019da8 c00194d0 c04b1fc0 0000000d c056f000 b6bb8000 c2d60780 00000103
5dc0: 00281000 c5000000 c36d5e04 c36d5dd8 c0075b58 c000efec c36d5e04 c36d5de8
5de0: c033c164 c2c349a0 c365e264 c364a20c c37abd60 00281000 c36d5e14 c36d5e08
5e00: c0075cd8 c0075b30 c36d5e4c c36d5e18 c0248ca0 c0075c88 00000003 b6bb8000
5e20: 00000000 c364a20c c2c349a0 c365ed80 c2d60780 b6bb8000 00000281 c37a6688
5e40: c36d5e64 c36d5e50 c0246608 c0248b58 c2c349a0 c364a000 c36d5e7c c36d5e68
5e60: c0250364 c0246548 c3611a00 c2c349a0 c36d5e9c c36d5e80 c0235c90 c0250334
5e80: c035c608 c2c349a0 000000ff c365ed80 c36d5f04 c36d5ea0 c007ab78 c0235c2c
5ea0: 000000ff 00000000 c365ed80 00000000 00000000 c365ed80 00000001 00281000
5ec0: b6e39000 00000000 00000007 c374bcd4 c374bcdc c374b8f0 c36d5f04 c365ed80
5ee0: 000000ff 00281000 00000007 00000001 00000000 c2d60780 c36d5f44 c36d5f08
5f00: c007b034 c007a950 000000ff 00000000 c365ed80 00000281 c36d5f34 c2d607b4
5f20: c365ed80 00000003 00280400 00000000 c36d4000 00000000 c36d5f74 c36d5f48
5f40: c006efd0 c007adbc 00000001 00000000 c36d5f74 c365ed80 00000001 00000003
5f60: 00280400 00000000 c36d5fa4 c36d5f78 c0079364 c006ef7c 00000001 00000000
5f80: 00001000 00000003 00000000 00008598 000000c0 c00095a4 00000000 c36d5fa8
5fa0: c0009420 c00792f8 00000003 00000000 00000000 00280400 00000003 00000001
5fc0: 00000003 00000000 00008598 000000c0 00000000 00000000 b6f9c000 bef89c94
5fe0: 00000000 bef89b58 00008b54 b6ef8908 40000010 00000000 00000000 00000000
Backtrace:
[<c000efdc>] (flush_dcache_page+0x0/0x1b8) from [<c0075b58>]
(insert_page+0x38/0x158)
[<c0075b20>] (insert_page+0x0/0x158) from [<c0075cd8>]
(vm_insert_page+0x60/0x6c)
r8:00281000 r7:c37abd60 r6:c364a20c r5:c365e264 r4:c2c349a0
[<c0075c78>] (vm_insert_page+0x0/0x6c) from [<c0248ca0>]
(__videobuf_mmap_mapper+0x158/0x1f4)
[<c0248b48>] (__videobuf_mmap_mapper+0x0/0x1f4) from [<c0246608>]
(videobuf_mmap_mapper+0xd0/0x114)
[<c0246538>] (videobuf_mmap_mapper+0x0/0x114) from [<c0250364>]
(vpif_mmap+0x40/0x50)
r5:c364a000 r4:c2c349a0
[<c0250324>] (vpif_mmap+0x0/0x50) from [<c0235c90>] (v4l2_mmap+0x74/0x98)
r5:c2c349a0 r4:c3611a00
[<c0235c1c>] (v4l2_mmap+0x0/0x98) from [<c007ab78>] (mmap_region+0x238/0x46c)
r6:c365ed80 r5:000000ff r4:c2c349a0 r3:c035c608
[<c007a940>] (mmap_region+0x0/0x46c) from [<c007b034>]
(do_mmap_pgoff+0x288/0x2e8)
[<c007adac>] (do_mmap_pgoff+0x0/0x2e8) from [<c006efd0>]
(vm_mmap_pgoff+0x64/0x7c)
[<c006ef6c>] (vm_mmap_pgoff+0x0/0x7c) from [<c0079364>]
(sys_mmap_pgoff+0x7c/0x9c)
r8:00000000 r7:00280400 r6:00000003 r5:00000001 r4:c365ed80
[<c00792e8>] (sys_mmap_pgoff+0x0/0x9c) from [<c0009420>]
(ret_fast_syscall+0x0/0x2c)
r8:c00095a4 r7:000000c0 r6:00008598 r5:00000000 r4:00000003
Code: 11a05003 1a000008 e3550000 0a000006 (e5953014)
---[ end trace 57f3e388e320b7e4 ]--
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