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

[Marek Szyprowski]

Hi Ming,

On 2019-02-21 10:57, Ming Lei wrote:
> On Thu, Feb 21, 2019 at 09:42:59AM +0100, 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
>>
>> ...
>>
>> EXT4-fs (mmcblk0p2): INFO: recovery required on readonly filesystem
>> EXT4-fs (mmcblk0p2): write access will be enabled during recovery
>> EXT4-fs (mmcblk0p2): recovery complete
>> EXT4-fs (mmcblk0p2): mounted filesystem with ordered data mode. Opts: (null)
>> VFS: Mounted root (ext4 filesystem) readonly on device 179:2.
>> devtmpfs: mounted
>> Freeing unused kernel memory: 1024K
>> hub 1-3:1.0: USB hub found
>> Run /sbin/init as init process
>> hub 1-3:1.0: 3 ports detected
>> *** stack smashing detected ***: <unknown> terminated
>> Kernel panic - not syncing: Attempted to kill init! exitcode=0x00000004
>> CPU: 1 PID: 1 Comm: init Not tainted 5.0.0-rc6-next-20190218 #1546
>> Hardware name: SAMSUNG EXYNOS (Flattened Device Tree)
>> [<c01118d0>] (unwind_backtrace) from [<c010d794>] (show_stack+0x10/0x14)
>> [<c010d794>] (show_stack) from [<c09ff8a4>] (dump_stack+0x90/0xc8)
>> [<c09ff8a4>] (dump_stack) from [<c0125944>] (panic+0xfc/0x304)
>> [<c0125944>] (panic) from [<c012bc98>] (do_exit+0xabc/0xc6c)
>> [<c012bc98>] (do_exit) from [<c012c100>] (do_group_exit+0x3c/0xbc)
>> [<c012c100>] (do_group_exit) from [<c0138908>] (get_signal+0x130/0xbf4)
>> [<c0138908>] (get_signal) from [<c010c7a0>] (do_work_pending+0x130/0x618)
>> [<c010c7a0>] (do_work_pending) from [<c0101034>]
>> (slow_work_pending+0xc/0x20)
>> Exception stack(0xe88c3fb0 to 0xe88c3ff8)
>> 3fa0:ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ 00000000 bea7787c 00000005
>> b6e8d0b8
>> 3fc0: bea77a18 b6f92010 b6e8d0b8 00000001 b6e8d0c8 00000001 b6e8c000
>> bea77b60
>> 3fe0: 00000020 bea77998 ffffffff b6d52368 60000050 ffffffff
>> CPU3: stopping
>>
>> I would like to help debugging and fixing this issue, but I don't really
>> have idea where to start. Here are some more detailed information about
>> my test system:
>>
>> 1. Board: ARM 32bit Samsung Exynos4412-based Odroid U3 (device tree
>> source: arch/arm/boot/dts/exynos4412-odroidu3.dts)
>>
>> 2. Block device: MMC/SDHCI/SDHCI-S3C with SD card
>> (drivers/mmc/host/sdhci-s3c.c driver, sdhci_2 device node in the device
>> tree)
>>
>> 3. Rootfs: Ext4
>>
>> 4. Kernel config: arch/arm/configs/exynos_defconfig
>>
>> I can gather more logs if needed, just let me which kernel option to
>> enable. Reverting this commit on top of next-20190218 as well as current
>> linux-next (tested with next-20190221) fixes this issue and makes the
>> system bootable again.
> Could you test the patch in following link and see if it can make a difference?
>
> https://marc.info/?l=linux-aio&m=155070355614541&w=2

I've tested that patch, but it doesn't make any difference on the test
system. In the log I see no warning added by it.

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