Re: Serious memory leak in TI EDMA driver (drivers/dma/edma.c)

[Peter Ujfalusi <peter.ujfalusi@ti.com>]

Petr,

On 03/17/2015 09:02 PM, Petr Kulhavy wrote:
> Hi Peter,
> 
> thanks a lot for the details.
> I believe it's not an Ethernet issue, it's really related to the SD card. If
> we use the USB storage instead of the SD card on our device we don't see the
> leaks.

I believe you are not booting with DT. The two eDMA is only supported when
booting in legacy mode.

> I enabled the dynamic debug and added a debug message for the kzalloc() in
> edma_prep_slave_sg() and for the kfree() in the edma_desc_free() both to print
> the pointer address. And it gives an interesting result, see below.
> 
> You can see that after every alloc (i.e.edma_prep_slave_sg()) edma_execute()
> is called ("file transfer starting..."), however not all of them end with
> "Transfer complete". And exactly those are also not freed.

I did the same on am335x-evmsk and I don't see the same issue (linux-next). It
does not mean that we do not have the issue you describe, but somehow it is
not that easy to reproduce. I will try my OMAP-L138 board, which is closer to
AM1808 than AM335x.

> Unfortunately I do not know how exactly the edma mechanism works with all the
> callbacks, states, etc.
> But does it make any sense for you? Can you help me to debug more?

Not sure at the moment, but I would try to print also in the error cases in
the callback and track the edesc pointer in every prints to see where the code
goes. I would enable the prints in the edma_execute as well to see what is
going on there.

For reference I have these prints:
[  924.127638] ALLOC edesc: 0xcd948c40 (channel: 25, sg_len: 1, rounds: 1)
[  924.134598] first transfer starting on channel 25 (edesc: 0xcd948c40)
[  924.145505] Transfer complete, stopping channel: 25 (edesc: 0xcd948c40)
[  924.152561] FREE edesc: 0xcd948c40 (channel: 25)
[  924.159223] ALLOC edesc: 0xc916f800 (channel: 25, sg_len: 30, rounds: 2)
[  924.166611] first transfer starting on channel 25 (edesc: 0xc916f800)
[  924.180541] Intermediate transfer complete on channel: 25 (edesc: 0xc916f800)
[  924.188054] chan: 25: completed 30 elements, resuming (edesc: 0xc916f800)
[  924.195208] Error occurred on channel: 25 (edesc: 0xc916f800), TRIGGERING
[  924.204117] Transfer complete, stopping channel: 25 (edesc: 0xc916f800)
[  924.211158] FREE edesc: 0xc916f800 (channel: 25)
[  924.218407] ALLOC edesc: 0xc6cbce00 (channel: 25, sg_len: 8, rounds: 1)
[  924.225396] first transfer starting on channel 25 (edesc: 0xc6cbce00)
[  924.236530] Transfer complete, stopping channel: 25 (edesc: 0xc6cbce00)
[  924.243506] FREE edesc: 0xc6cbce00 (channel: 25)
[  924.248817] ALLOC edesc: 0xcaa5ec00 (channel: 25, sg_len: 12, rounds: 1)
[  924.256068] first transfer starting on channel 25 (edesc: 0xcaa5ec00)
[  924.268277] Transfer complete, stopping channel: 25 (edesc: 0xcaa5ec00)
[  924.275265] FREE edesc: 0xcaa5ec00 (channel: 25)



> Thanks
> Petr
> 
> ALLOC edesc c65d5c80
> first transfer starting on channel 65565

The channel number does not seams right here.

> ALLOC edesc c5b69640

Would be nice to see the channel as well here. But sure the FREE for c65d5c80
is missing. Strange, I don't see how this happens.
I have enabled PREEMPT and still can not reproduce - this was my first idea.

> first transfer starting on channel 65565
> Transfer complete, stopping channel 29
> FREE edesc c5b69640
> ALLOC edesc c58ec580
> first transfer starting on channel 65565
> Transfer complete, stopping channel 29
> FREE edesc c58ec580
> ALLOC edesc c5103d80
> first transfer starting on channel 65565
> ALLOC edesc c61e78c0
> first transfer starting on channel 65565
> ALLOC edesc c65d6f80
> first transfer starting on channel 65565
> Transfer complete, stopping channel 29
> FREE edesc c65d6f80
> ALLOC edesc c5b698c0
> first transfer starting on channel 65565
> Transfer complete, stopping channel 29
> FREE edesc c5b698c0
> ALLOC edesc c52244c0
> first transfer starting on channel 65565
> Transfer complete, stopping channel 29
> FREE edesc c52244c0
> ALLOC edesc c52244c0
> first transfer starting on channel 65565
> Transfer complete, stopping channel 29
> FREE edesc c52244c0
> ALLOC edesc c52244c0
> first transfer starting on channel 65565
> Transfer complete, stopping channel 29
> FREE edesc c52244c0
> ALLOC edesc c52244c0
> first transfer starting on channel 65565
> Transfer complete, stopping channel 29
> FREE edesc c52244c0
> ALLOC edesc c58ec580
> first transfer starting on channel 65565
> ALLOC edesc c5b698c0
> first transfer starting on channel 65565
> ALLOC edesc c5103480
> first transfer starting on channel 65565
> Transfer complete, stopping channel 29
> FREE edesc c5103480
> ALLOC edesc c5b69640
> first transfer starting on channel 65565
> Transfer complete, stopping channel 29
> FREE edesc c5b69640
> ALLOC edesc c61e62c0
> first transfer starting on channel 65565
> Transfer complete, stopping channel 29
> FREE edesc c61e62c0
> ALLOC edesc c5227440
> first transfer starting on channel 65565
> Transfer complete, stopping channel 29
> FREE edesc c5227440
> ALLOC edesc c5b69640
> first transfer starting on channel 65565
> ALLOC edesc c5b69b40
> first transfer starting on channel 65565
> ALLOC edesc c5233000
> first transfer starting on channel 65565
> ALLOC edesc c5233dc0
> first transfer starting on channel 65565
> ALLOC edesc c5233140
> first transfer starting on channel 65565
> Transfer complete, stopping channel 29
> FREE edesc c5233140
> ALLOC edesc c5233140
> first transfer starting on channel 65565
> ALLOC edesc c5233280
> first transfer starting on channel 65565
> Transfer complete, stopping channel 29
> FREE edesc c5233280
> 

-- 
Péter
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