Re: [PATCH V2 3/3] Adding device_dma_parameters->offset_preserve_mask to NVMe driver.

[Chaitanya Kulkarni]

On 2/1/21 13:27, Jianxiong Gao wrote:
>> Why is this setting being done and undone on each IO? Wouldn't it be
>> more efficient to set it once during device initialization?
>>
>> And more importantly, this isn't thread safe: one CPU may be setting the
>> device's dma alignment mask to 0 while another CPU is expecting it to be
>> NVME_CTRL_PAGE_SIZE - 1.
>  I was having trouble getting the OS booted when setting it once during
>  initialization. However when I rebased to the latest rc6 this morning it
>  seems to be working with setting the mask on probe. I am still testing out
>  and will appreciate any idea what may cause the nvme driver to fail
>  with a single mask.
Based on the Keith's comment it needs to be completely avoided in hot path.

Did you get a chance to bisect the problem in the rc6 ? We need to know the
root cause otherwise it might happen again after we add this patch.