Re: imx27: No space left to write bad block table

Guillaume Tucker
2021-04-22T13:17:42Z

+Jan, +kernelci-results

On 22/04/2021 00:29, Fabio Estevam wrote:
> Hi Guillaume,
>
> On Wed, Apr 21, 2021 at 5:44 PM Guillaume Tucker
> <guillaume.tucker@collabora.com> wrote:
>
>> Sorry I'm late to the party, was busy with some other kernelci
>> issues. I gather this is being reverted anyway now, but please
>> let me know if you still need to check anything. As far as I can
>> tell, there hasn't been any automated bisection landing on this
>> commit.
>
> Thanks. Yes, we did the revert in linux-next, but I could not see the
> next-20210421 boot log for the imx27-phytec-phycard-s-rdk board to
> confirm that the NAND bad block table can be found again.

This device is only available in Pengutronix's lab which is
currently being moved to a new location, so I'm being told. I
guess we'll check again when it's back online.

Are you aware of any other platform in KernelCI showing the same
issue? I could take a look but there's been more boot failure
regressions than usual on linux-next recently...

Best wishes,
Guillaume

>> It's generally possible to re-run anything, i.e. make a kernel
>> build with a custom patchset and run one given test on any of the
>> platforms in KernelCI. There just isn't any public self-service
>> for doing that (yet).
>>
>> Best wishes,
>> Guillaume
>>
>>>>> I have tested this on an i.MX 6 by simulating two bad BBT blocks by simply
>>>>> returning -EIO in nand_erase_nand when the block to be erased is one of
>>>>> the
>>>>> first two BBT blocks.
>>>>>
>>>>> I have seen this once on a customer board but were not able to reproduce
>>>>> it
>>>>> anymore, thus the simulation of the two bad blocks.
>>>>>
>>>>> Without the patch below new versions of the BBT can no longer be written
>>>>> to
>>>>> the first two blocks reserved for the BBT but they are still evaluated to
>>>>> read
>>>>> the BBT from during boot due the lack of a test if these blocks are bad.
>>>>> So
>>>>> changes to the BBT after these two blocks turn bad are only kept and used
>>>>> until the next reboot where again the old version of the two worn blocks
>>>>> is
>>>>> used as a basis.
>>>>>
>>>>> I tried to use the same mechanism that is used to identify bad blocks
>>>>> during a
>>>>> scan for bad blocks. But maybe I missed something there? Or were my
>>>>> assumptions wrong in the first place?
>>>>
>>>> Honestly I don't know what is wrong exactly in this patch.
>>>>
>>>> We will revert the commit as it clearly breaks something fundamental
>>>> and the merge window is too close to adopt a hackish attitude.
>>>>
>>>> I would propose the following tests with your board:
>>>> - Hack the core to allow yourself to access bad blocks from userspace
>>>> for testing purposes.
>>>> - With the below commit, you should have the same behavior than
>>>> reported by Fabio.
>>>> - Revert the commit.
>>>> - Manually change the bad block markers (nanddump, flash_erase,
>>>> nandwrite) to declare the two tables bad. Reboot and observe if there
>>>> are any issues. You can try to work from there.
>>>
>>> Thanks for the input! I will follow your suggestions and let you guys know my
>>> findings.
>>>
>>> Regards,
>>> Stefan
>>>
>>>>
>>>>>> ---8<---
>>>>>>
>>>>>> commit bd9c9fe2ad04546940f4a9979d679e62cae6aa51
>>>>>> Author: Stefan Riedmueller <s.riedmueller@phytec.de>
>>>>>> Date: Thu Mar 25 11:23:37 2021 +0100
>>>>>>
>>>>>> mtd: rawnand: bbt: Skip bad blocks when searching for the BBT in
>>>>>> NAND
>>>>>>
>>>>>> The blocks containing the bad block table can become bad as well. So
>>>>>> make sure to skip any blocks that are marked bad when searching for
>>>>>> the
>>>>>> bad block table.
>>>>>>
>>>>>> Otherwise in very rare cases where two BBT blocks wear out it might
>>>>>> happen that an obsolete BBT is used instead of a newer available
>>>>>> version.
>>>>>>
>>>>>> Signed-off-by: Stefan Riedmueller <s.riedmueller@phytec.de>
>>>>>> Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
>>>>>> Link:
>>>>>> https://lore.kernel.org/linux-mtd/20210325102337.481172-1-s.riedmueller@phytec.de
>>>>>>
>>>>>> diff --git a/drivers/mtd/nand/raw/nand_bbt.c
>>>>>> b/drivers/mtd/nand/raw/nand_bbt.c
>>>>>> index dced32a126d9..6e25a5ce5ba9 100644
>>>>>> --- a/drivers/mtd/nand/raw/nand_bbt.c
>>>>>> +++ b/drivers/mtd/nand/raw/nand_bbt.c
>>>>>> @@ -525,6 +525,7 @@ static int search_bbt(struct nand_chip *this,
>>>>>> uint8_t
>>>>>> *buf,
>>>>>> {
>>>>>> u64 targetsize = nanddev_target_size(&this->base);
>>>>>> struct mtd_info *mtd = nand_to_mtd(this);
>>>>>> + struct nand_bbt_descr *bd = this->badblock_pattern;
>>>>>> int i, chips;
>>>>>> int startblock, block, dir;
>>>>>> int scanlen = mtd->writesize + mtd->oobsize;
>>>>>> @@ -560,6 +561,10 @@ static int search_bbt(struct nand_chip *this,
>>>>>> uint8_t
>>>>>> *buf,
>>>>>> int actblock = startblock + dir * block;
>>>>>> loff_t offs = (loff_t)actblock << this-
>>>>>>> bbt_erase_shift;
>>>>>>
>>>>>> + /* Check if block is marked bad */
>>>>>> + if (scan_block_fast(this, bd, offs, buf))
>>>>>> + continue;
>>>>>> +
>>>>>> /* Read first page */
>>>>>> scan_read(this, buf, offs, mtd->writesize, td);
>>>>>> if (!check_pattern(buf, scanlen, mtd->writesize,
>>>>>> td)) {
>>>>>>
>>>>>>
>>>>>> Thanks,
>>>>>> Miquèl
>>>>
>>>> Thanks,
>>>> Miquèl
>>