Re: [PATCH V15 14/18] block: enable multipage bvecs

[Marek Szyprowski]

Hi Ming,

On 2019-02-28 00:29, Ming Lei wrote:
> On Wed, Feb 27, 2019 at 08:47:09PM +0000, Jon Hunter wrote:
>> On 21/02/2019 08:42, Marek Szyprowski wrote:
>>> On 2019-02-15 12:13, Ming Lei wrote:
>>>> This patch pulls the trigger for multi-page bvecs.
>>>>
>>>> Reviewed-by: Omar Sandoval <osandov@xxxxxx>
>>>> Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxx>
>>> Since Linux next-20190218 I've observed problems with block layer on one
>>> of my test devices (Odroid U3 with EXT4 rootfs on SD card). Bisecting
>>> this issue led me to this change. This is also the first linux-next
>>> release with this change merged. The issue is fully reproducible and can
>>> be observed in the following kernel log:
>>>
>>> sdhci: Secure Digital Host Controller Interface driver
>>> sdhci: Copyright(c) Pierre Ossman
>>> s3c-sdhci 12530000.sdhci: clock source 2: mmc_busclk.2 (100000000 Hz)
>>> s3c-sdhci 12530000.sdhci: Got CD GPIO
>>> mmc0: SDHCI controller on samsung-hsmmc [12530000.sdhci] using ADMA
>>> mmc0: new high speed SDHC card at address aaaa
>>> mmcblk0: mmc0:aaaa SL16G 14.8 GiB
>> I have also noticed some failures when writing to an eMMC device on one
>> of our Tegra boards. We have a simple eMMC write/read test and it is
>> currently failing because the data written does not match the source.
>>
>> I did not seem the same crash as reported here, however, in our case the
>> rootfs is NFS mounted and so probably would not. However, the bisect
>> points to this commit and reverting on top of -next fixes the issues.
> It is sdhci, probably related with max segment size, could you test the
> following patch:
>
> https://marc.info/?l=linux-mmc&m=155128334122951&w=2

This seems to be fixing my issue too! Thanks!

It also fixed the boot issue from USB stick (Exynos EHCI / Mass
Storage), but I suspect that reading the partition table from the sd
card (which hold the bootloader and thus must be present to boot the
device) was enough to trash memory/page cache and break the boot process.

Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland