Re: Bug in v7_coherent_kern_range() ?

[Huang Shijie <b32955@xxxxxxxxxxxxx>]

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.


> 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.

> > [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.
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
> >
> >
> >
> >
> >
> > _______________________________________________
> > linux-arm-kernel mailing list
> > linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
> > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel



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