Re: Bug in v7_coherent_kern_range() ?

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On 01.04.2012 10:16, Huang Shijie wrote:
Hi Dirk:
Hi Huang Shijie,

On 01.04.2012 09:09, Huang Shijie wrote:
Hi Dirk:
Hi Huang Shijie,

On 01.04.2012 05:21, Huang Shijie wrote:
[1] Platform:
freescale's IMX6Q(4 cores) , ARM CORTEX-A9

[2] kernel:
3.0.15(I have cherry-picked many patches, and the
arch/arm/mm/cache-v7.S
is same code with the latest kernel v3.4-rc1)
enable SMP, VIPT,

Could you try an unpatched, clean v3.4-rc1 instead?
Sorry, I could not try the v3.4-rc1. Some our bsp drivers are not DT
supported.

I think we are not talking about drivers, we are talking about some
kernel core code, like cache handling? To test
v7_coherent_kern_range() you might not need to many bsp drivers?
Yes , the gplay will use the vpu driver. But the VPU driver is not in
the kernel. Without the vpu driver, the gplay can not works.

You could try to disable the vpu driver and check if the issue is still there, then.

What's about your 2.6.38?
2.6.38 is not a good version to run the imx6q. It losts many our
drivers's patches.

What's about 3.0.26? 3.0.15 seems to miss some maybe relevant
patches.

Our bsp release are based on 3.0.15. so we could not test it on 3.0.26
too.

You can. Just give git rebase a try.
It will be a nightmare to me. We have nearly 1000 patches. I will cost
me much time to handle the conflicts.

IMHO you will get one easy to solve merge conflict. So it should you take < 10min to rebase to 3.0.26. Just try it ;)


[3] application:

Could you share a (simple) test case?
The test case is like this:
#gplay xx.avi

gplay is our own player, such as mplayer.

Could you share a (simple) test case? E.g. share 'gplay'? Or try to
reproduce your issue with an other test case? E.g. mplayer? Or
better anything simpler the community can use to try to reproduce
your issue?
I can email to you the gplay, if you have an imx6q board. you can test
it.
I just wish someone give me some advice about this issue.

It would help to use a kernel version and a test case the community can use to reproduce.

Best regards

Dirk

I find the arch/arm/include/asm/assembler.h is out of date. So I will
update it and test it again.

thanks a lot , Dirk.

Huang Shijie

Best regards

Dirk

I just created a script which will play the video files one by one.

BR
Huang Shijie


Best regards

Dirk

I use our our application which will clone many threads,
two threads (assume as A and B) may do the same thing at the same
time
as the following code:

In most of the time, it's ok.
But in some unknown situation, cacheflush() failed and one threads
(assume A) may hung up in the following code:
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++



open("/usr/lib/lib_mp3_dec_arm12_elinux.so.2.10.0", O_RDONLY) = 8
read(8,
"\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0(\0\1\0\0\0\20\35\0\0004\0\0\0"...,


512) = 512
fstat64(8, {st_mode=S_IFREG|0644, st_size=56232, ...}) = 0
mmap2(NULL, 88032, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE,
8, 0)
= 0x2ff0a000
mprotect(0x2ff18000, 28672, PROT_NONE) = 0
mmap2(0x2ff1f000, 4096, PROT_READ|PROT_WRITE,
MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 8, 0xd) = 0x2ff1f000
close(8) = 0
mprotect(0x2ff0a000, 57344, PROT_READ|PROT_WRITE) = 0
mprotect(0x2ff0a000, 57344, PROT_READ|PROT_EXEC) = 0
cacheflush(0x2ff0a000, 0x2ff18000, 0, 0x6, 0x2cd03420) = 0 // System
hung up here!!!
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++




[4] kernel log
I use "echo t> /proc/sysrq-trigger" to show the tasks's information:
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++



multiqueue0:src D 804cd678 0 7328 5963 0x00000001
[<804cd678>] (__schedule+0x228/0x760) from [<804d0564>]
(__down_read+0xa8/0xe0)
[<804d0564>] (__down_read+0xa8/0xe0) from [<800478c4>]
(do_page_fault+0xbc/0x480)
[<800478c4>] (do_page_fault+0xbc/0x480) from [<8003841c>]
(do_DataAbort+0x34/0x98)
[<8003841c>] (do_DataAbort+0x34/0x98) from [<8003df10>]
(__dabt_svc+0x70/0xa0)
Exception stack(0xbae37ea8 to 0xbae37ef0)
7ea0: 31e05000 31e1d000 00000020 0000001f 31e05000 31e1d000
7ec0: bfac86b8 31e05000 31e1d000 bae36000 08100075 31e056fc 31e08000
bae37ef0
7ee0: 800424a8 8004a1fc 800f0013 ffffffff
[<8003df10>] (__dabt_svc+0x70/0xa0) from [<8004a1fc>]
(v7_coherent_kern_range+0x20/0x80)
[<8004a1fc>] (v7_coherent_kern_range+0x20/0x80) from [<800424a8>]
(arm_syscall+0x2a0/0x2c4)
[<800424a8>] (arm_syscall+0x2a0/0x2c4) from [<8003e500>]
(ret_fast_syscall+0x0/0x3c)
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++




The do_cache_op() has already held the mm->mmap_sem, but
v7_coherent_kern_range()
cause one page fault during it flush the cache. deadlock! So it
hung up
in the do_page_fault().

[5] questions:
Why the v7_coherent_kern_range() can caused the data abort?
Is there something wrong about the v7_coherent_kern_range()?


thanks
Huang Shijie





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