Hi Hans,
On Fri, Jun 22, 2012 at 1:20 PM, Hans Verkuil <hverkuil@xxxxxxxxx> wrote:
> 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.
>
I have also created a same patch, shall I post It ? I have tested it
is working for VPIF capture and display.
Thx,
--Prabhakar Lad
> 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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