Re: Page allocation issue

On Fri, Nov 02, 2007 at 05:28:56PM +0900, Hirofumi Momose wrote:
> Hello, 
> I am totally newbie to this ML. 
> 
> I am developping web camera on ARM-9 platform.
> It works fine for a while, but finally got following error.
> 
> ------------ Kernel message --------------
> webcam: page allocation failure. order:5, mode:0x0
> [<c002a434>] (dump_stack+0x0/0x14) from [<c006ed70>] (__alloc_pages+0x2b4/0x2c8)
> [<c006eabc>] (__alloc_pages+0x0/0x2c8) from [<c002bd78>] (__dma_alloc+0x188/0x3dc)
> [<c002bbf0>] (__dma_alloc+0x0/0x3dc) from [<c002c01c>] (dma_alloc_coherent+0x24/0x2c)
> [<c002bff8>] (dma_alloc_coherent+0x0/0x2c) from [<c0249350>] (hcd_buffer_alloc+0x8c/0x94)
> [<c02492c4>] (hcd_buffer_alloc+0x0/0x94) from [<c02407b8>] (usb_buffer_alloc+0x24/0x30)
>  r5:c07c2030 r4:c0aff400
> [<c0240794>] (usb_buffer_alloc+0x0/0x30) from [<bf018500>] (uvc_init_video+0x15c/0x3b0 [uvcv
> 
> [<bf0183a4>] (uvc_init_video+0x0/0x3b0 [uvcvideo]) from [<bf0187bc>] (uvc_video_enable+0x68/
> 
> [<bf018754>] (uvc_video_enable+0x0/0x6c [uvcvideo]) from [<bf0181b8>] (uvc_v4l2_do_ioctl+0xc
> 
>  r6:c07c2030 r5:c4185e74 r4:40045612
> [<bf017544>] (uvc_v4l2_do_ioctl+0x0/0xda4 [uvcvideo]) from [<bf00e930>] (video_usercopy+0x21
> 
> [<bf00e720>] (video_usercopy+0x0/0x33c [videodev]) from [<bf016f20>] (uvc_v4l2_ioctl+0x54/0x
> 
> [<bf016ecc>] (uvc_v4l2_ioctl+0x0/0x64 [uvcvideo]) from [<c009552c>] (do_ioctl+0x68/0x78)
>  r7:00000003 r6:40045612 r5:000250a4 r4:40045612
> [<c00954c4>] (do_ioctl+0x0/0x78) from [<c009579c>] (vfs_ioctl+0x260/0x288)
>  r5:000250a4 r4:c279a200
> [<c009553c>] (vfs_ioctl+0x0/0x288) from [<c0095804>] (sys_ioctl+0x40/0x60)
>  r7:c279a200 r6:40045612 r5:000250a4 r4:00000003
> [<c00957c4>] (sys_ioctl+0x0/0x60) from [<c0025fa0>] (ret_fast_syscall+0x0/0x2c)
>  r7:00000036 r6:000250a4 r5:00000000 r4:00000000
> Mem-info:
> DMA per-cpu:
> CPU    0: Hot: hi:   42, btch:   7 usd:   5   Cold: hi:   14, btch:   3 usd:  13
> Active:5931 inactive:22401 dirty:158 writeback:0 unstable:0
>  free:1021 slab:1351 mapped:1075 pagetables:70 bounce:0
> DMA free:4084kB min:1440kB low:1800kB high:2160kB active:23724kB inactive:89604kB present:13
> able
> 
> lowmem_reserve[]: 0 0
> DMA: 467*4kB 85*8kB 28*16kB 8*32kB 11*64kB 1*128kB 0*256kB 0*512kB 0*1024kB 0*2048kB 0*4096k
>  = 4084kB
> Swap cache: add 0, delete 0, find 0/0, race 0+0
> --------------End of Kernel message --------------
> 
> I think this might be caused by shortage of large pages.
> Just after booted, there are several large pages, and camera works fine.
> As time passes, large pages are split into many small pages, and camera
> fails.

How big are the buffers you are trying to allocate?

A lot of the video camera drivers are trying to allocate _way_ too big
of a buffer for no good reason.  Try decreasing the buffer sizes down to
2-3 times the endpoint size, which should fix your problem.

thanks,

greg k-h

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