On 2022/12/21 15:14, lijiang wrote:
> Thank you for the comment, Kazu.
>
> On Wed, Dec 21, 2022 at 1:48 PM HAGIO KAZUHITO(萩尾 一仁)
> <k-hagio-ab@xxxxxxx> wrote:
>>
>> On 2022/12/21 14:22, HAGIO KAZUHITO(萩尾 一仁) wrote:
>>> On 2022/12/20 12:16, Lianbo Jiang wrote:
>>>> Recently the following failure has been observed on some vmcores when
>>>> using the mount command:
>>>>
>>>> crash> mount
>>>> MOUNT SUPERBLK TYPE DEVNAME DIRNAME
>>>> ffff97a4818a3480 ffff979500013800 rootfs none /
>>>> ffff97e4846ca700 ffff97e484653000 sysfs sysfs /sys
>>>> ...
>>>> ffff97b484753420 0 mount: invalid kernel virtual address: 0 type: "super_block buffer"
>>>
>>> Thank you for the fix.
>>>
>>> Just out of curiosity, do you see why the vfsmount.mnt_sb is zero?
>>> That panic occurred during mounting or unmounting?
>>
>
> I didn't reproduce this issue, but I got several vmcores from
> customers and did the debugging.
>
> Maybe the super block has been released, but the data has not been
> completely synced. I guess.
OK.
>
>> I think, it might be more helpful to print the MOUNT and SUPERBLK values
>> in the list even if it's zero or invalid, rather than skip it completely.
>> What do you think? e.g. continue here:
>>
>
> Sounds good.
>
>> @@ -1500,6 +1500,11 @@ show_mounts(ulong one_vfsmount, int flags, struct task_context *namespace_contex
>> mkstring(buf2, VADDR_PRLEN, RJUST|LONG_HEX,
>> MKSTR(sbp)));
>>
>> + if (!IS_KVADDR(sbp)) {
>> + error(INFO, "cannot get super_block\n");
>
> + error(INFO, "cannot get super_block from
> vfsmnt: 0x%lx\n", *vfsmnt);
>
> If we would like to print the information, also try to output the vfs
> mount address, looks better?
ah, your example already has it and mnt_sb, so I didn't put them in the
error message.
>>>> crash> mount
>>>> MOUNT SUPERBLK TYPE DEVNAME DIRNAME
>>>> ffff97a4818a3480 ffff979500013800 rootfs none /
>>>> ffff97e4846ca700 ffff97e484653000 sysfs sysfs /sys
>>>> ...
>>>> ffff97b484753420 0 mount: invalid kernel virtual address: 0 type: "super_block buffer"
^^^^^^^^^^^^^^^^ ^^^^^^^^^^^^^^^^
but printing it again may be better, and WARNING may be better
in this case. Please play around for good output and can I have
an example output?
Thanks,
Kazu
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