On Tue, Nov 12, 2013 at 12:23:08PM +0800, Huang Shijie wrote: > The imx23 board will check the fingerprint, so it will call the > mx23_check_transcription_stamp. This function will use @chip->buffers->databuf > as its buffer which is allocated in the nand_scan_tail(). > > Unfortunately, the mx23_check_transcription_stamp is called before the > nand_scan_tail(). So we will meet a NULL pointer bug: > > -------------------------------------------------------------------- > [ 1.150000] NAND device: Manufacturer ID: 0xec, Chip ID: 0xd7 (Samsung NAND 4GiB 3,3V 8-bit), 4096MiB, page size: 4096, OOB size: 8 > [ 1.160000] Unable to handle kernel NULL pointer dereference at virtual address 000005d0 > [ 1.170000] pgd = c0004000 > [ 1.170000] [000005d0] *pgd=00000000 > [ 1.180000] Internal error: Oops: 5 [#1] ARM > [ 1.180000] Modules linked in: > [ 1.180000] CPU: 0 PID: 1 Comm: swapper Not tainted 3.12.0 #89 > [ 1.180000] task: c7440000 ti: c743a000 task.ti: c743a000 > [ 1.180000] PC is at memcmp+0x10/0x54 > [ 1.180000] LR is at gpmi_nand_probe+0x42c/0x894 > [ 1.180000] pc : [<c025fcb0>] lr : [<c02f6a68>] psr: 20000053 > [ 1.180000] sp : c743be2c ip : 600000d3 fp : ffffffff > [ 1.180000] r10: 000005d0 r9 : c02f5f08 r8 : 00000000 > [ 1.180000] r7 : c75858a8 r6 : c75858a8 r5 : c7585b18 r4 : c7585800 > [ 1.180000] r3 : 000005d0 r2 : 00000004 r1 : c05c33e4 r0 : 000005d0 > [ 1.180000] Flags: nzCv IRQs on FIQs off Mode SVC_32 ISA ARM Segment kernel > [ 1.180000] Control: 0005317f Table: 40004000 DAC: 00000017 > [ 1.180000] Process swapper (pid: 1, stack limit = 0xc743a1c0) > -------------------------------------------------------------------- > > This patch rearrange the init procedure: > Set the NAND_SKIP_BBTSCAN to skip the nand scan firstly, and after we > set the proper settings, we will call the chip->scan_bbt() manually. > > Cc: stable@xxxxxxxxxxxxxxx > Reported-by: Fabio Estevam <festevam@xxxxxxxxx> > Signed-off-by: Huang Shijie <b32955@xxxxxxxxxxxxx> This looks good. Thanks guys. Pushed to l2-mtd.git. I'm not sure how much sense all your function names make now; for instance, gpmi_pre_bbt_scan() doesn't have anything to do with the BBT scan any more, does it? Brian -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html