Hit BUG_ON in dma-mapping.c:425

[Nicolas Ferre]

Hi,

While running mtd_stresstest on a dataflash (atmel_spi 
+ mtd_dataflash drivers) I hit the BUG_ON directive that 
is at the beginning of ___dma_single_cpu_to_dev() function.
This function is called from the SPI driver that do a 
dma_map_single() before DMA operations on the buffer 
transmitted from upper layers.

It seems that this address is above "high_memory" limit because 
it is allocated by vmalloc (in mtd_stresstest.c:285)...

The question is: where the bug is relying? Is there a 
configuration that I must modify in AT91 Linux to be able 
to modify this behavior or is this an error in the use of 
dma_map_single() in the atmel_spi.c driver?

After searching the web, it seems it is quite common after 
2.6.34 kernels... But I cannot figure out what is the issue.

Here is the Oops output:
root@at91sam9m10g45ek:~# insmod ../n/mtd_stresstest.ko dev=3

=================================================
mtd_stresstest: MTD device: 3
mtd_stresstest: MTD device size 4325376, eraseblock size 528, page size 528, count of eraseblocks 8192, pages per eraseblock 1, OOB size 0
mtd_stresstest: doing operations
mtd_stresstest: 0 operations done
kernel BUG at /home/nferre/workspace/linux/linux-2.6-arm/arch/arm/mm/dma-mapping.c:425!
Unable to handle kernel NULL pointer dereference at virtual address 00000000
pgd = c31bc000
[00000000] *pgd=732b1031, *pte=00000000, *ppte=00000000
Internal error: Oops: 817 [#1]
last sysfs file: /sys/devices/platform/atmel-ehci/usb1/1-2/1-2:1.0/host0/target0:0:0/0:0:0:0/block/sda/size
Modules linked in: mtd_stresstest(+)
CPU: 0    Not tainted  (2.6.37+ #2)
PC is at __bug+0x1c/0x28
LR is at __bug+0x18/0x28
pc : [<c0030374>]    lr : [<c0030370>]    psr: 20000093
sp : c3b09df8  ip : 00000200  fp : 00601c00
r10: c4886000  r9 : 00001807  r8 : 74886000
r7 : c38d37a0  r6 : c39660e8  r5 : c3b09ebc  r4 : c3b09e98
r3 : 00000000  r2 : c3b09dec  r1 : c02ef2c1  r0 : 0000005e
Flags: nzCv  IRQs off  FIQs on  Mode SVC_32  ISA ARM  Segment user
Control: 0005317f  Table: 731bc000  DAC: 00000015
Process insmod (pid: 1649, stack limit = 0xc3b08270)
Stack: (0xc3b09df8 to 0xc3b0a000)
9de0:                                                       ffffffff c0032b1c
9e00: c3b09e98 c01817c4 c3966000 c3b09e3c 00000000 c38d37a0 c3966000 c018070c
9e20: 60000013 c3b09e3c 00000000 c018076c c3b09ebc c0180914 c38d37a0 00000000
9e40: c3b09e40 c3b09e40 c3979e00 00000420 c3b09f2c 00000210 00601c00 c0179ba8
9e60: 00100100 00318e70 c38d37a0 c3979e24 00000000 c3979e00 00000000 00000004
9e80: 73979e00 ffffffff 00000000 00000000 c3b09eb4 c3b09ebc c4886000 00000000
9ea0: 00000210 ffffffff ffffffff 00000000 00000000 c3b09ebc c3b09e90 c3b09e90
9ec0: c3b09eb4 c38d37a0 00000000 c0180ab8 c3b09e3c 00000000 ffffff8d 00000000
9ee0: 00000000 00000000 00000000 00000000 00000000 00001807 00000000 0000601c
9f00: 00318e70 00000420 00001808 bf0034b0 00000420 c3b09f2c c4886000 00000001
9f20: 00000000 00000000 00000000 00000000 0000002e bf0005fc bf003000 00012008
9f40: 00000000 c002cfa8 c3b08000 00000000 00012008 c002740c c035ecf4 00000001
9f60: bf0005fc 00000000 00012008 bf0005fc 00000000 00012008 00011d23 c002cfa8
9f80: 00000000 c0062dec 00012018 00011d23 00012008 00000000 00012008 00020000
9fa0: 00000080 c002ce00 00000000 00012008 00012018 00011d23 00012008 00000001
9fc0: 00000000 00012008 00020000 00000080 bec09efb bec09ef4 00012018 00012008
9fe0: 00000003 bec09c94 00008d77 401c0054 60000010 00012018 657a6973 69657700
[<c0030374>] (__bug+0x1c/0x28) from [<c0032b1c>] (___dma_single_cpu_to_dev+0x34/0x5c)
[<c0032b1c>] (___dma_single_cpu_to_dev+0x34/0x5c) from [<c01817c4>] (atmel_spi_transfer+0xc8/0x1c4)
[<c01817c4>] (atmel_spi_transfer+0xc8/0x1c4) from [<c018070c>] (__spi_async+0x94/0xa0)
[<c018070c>] (__spi_async+0x94/0xa0) from [<c018076c>] (spi_async_locked+0x14/0x2c)
[<c018076c>] (spi_async_locked+0x14/0x2c) from [<c0180914>] (__spi_sync+0x5c/0x9c)
[<c0180914>] (__spi_sync+0x5c/0x9c) from [<c0179ba8>] (dataflash_write+0x180/0x1fc)
[<c0179ba8>] (dataflash_write+0x180/0x1fc) from [<bf0034b0>] (mtd_stresstest_init+0x4b0/0x604 [mtd_stresstest])
[<bf0034b0>] (mtd_stresstest_init+0x4b0/0x604 [mtd_stresstest]) from [<c002740c>] (do_one_initcall+0xcc/0x1a8)
[<c002740c>] (do_one_initcall+0xcc/0x1a8) from [<c0062dec>] (sys_init_module+0x90/0x1a4)
[<c0062dec>] (sys_init_module+0x90/0x1a4) from [<c002ce00>] (ret_fast_syscall+0x0/0x2c)
Code: e59f0010 e1a01003 eb0916de e3a03000 (e5833000)
---[ end trace 0f2f3786a6a31f57 ]---
Segmentation fault

This append on 2.6.37 kernel.

Thanks for your help. Best regards,

-- 
Nicolas Ferre

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