Re: kernel null pointer at nvme_tcp_init_iter+0x7d/0xd0 [nvme_tcp]

[Sagi Grimberg <sagi@grimberg.me>]

>> Hi Sagi
>>
>> On 2/8/21 5:46 PM, Sagi Grimberg wrote:
>>>
>>>> Hello
>>>>
>>>> We found this kernel NULL pointer issue with latest 
>>>> linux-block/for-next and it's 100% reproduced, let me know if you 
>>>> need more info/testing, thanks
>>>>
>>>> Kernel repo: 
>>>> https://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux-block.git
>>>> Commit: 11f8b6fd0db9 - Merge branch 'for-5.12/io_uring' into for-next
>>>>
>>>> Reproducer: blktests nvme-tcp/012
>>>
>>> Thanks for reporting Ming, I've tried to reproduce this on my VM
>>> but did not succeed. Given that you have it 100% reproducible,
>>> can you try to revert commit:
>>>
>>> 0dc9edaf80ea nvme-tcp: pass multipage bvec to request iov_iter
>>>
>>
>> Revert this commit fixed the issue and I've attached the config. :)
> 
> Good to know,
> 
> I see some differences that I should probably change to hit this:
> -- 
> @@ -254,14 +256,15 @@ CONFIG_PERF_EVENTS=y
>   # end of Kernel Performance Events And Counters
> 
>   CONFIG_VM_EVENT_COUNTERS=y
> +CONFIG_SLUB_DEBUG=y
>   # CONFIG_COMPAT_BRK is not set
> -CONFIG_SLAB=y
> -# CONFIG_SLUB is not set
> -# CONFIG_SLOB is not set
> -CONFIG_SLAB_MERGE_DEFAULT=y
> -# CONFIG_SLAB_FREELIST_RANDOM is not set
> +# CONFIG_SLAB is not set
> +CONFIG_SLUB=y
> +# CONFIG_SLAB_MERGE_DEFAULT is not set
> +CONFIG_SLAB_FREELIST_RANDOM=y
>   # CONFIG_SLAB_FREELIST_HARDENED is not set
> -# CONFIG_SHUFFLE_PAGE_ALLOCATOR is not set
> +CONFIG_SHUFFLE_PAGE_ALLOCATOR=y
> +CONFIG_SLUB_CPU_PARTIAL=y
>   CONFIG_SYSTEM_DATA_VERIFICATION=y
>   CONFIG_PROFILING=y
>   CONFIG_TRACEPOINTS=y
> @@ -299,7 +302,8 @@ CONFIG_HAVE_INTEL_TXT=y
>   CONFIG_X86_64_SMP=y
>   CONFIG_ARCH_SUPPORTS_UPROBES=y
>   CONFIG_FIX_EARLYCON_MEM=y
> -CONFIG_PGTABLE_LEVELS=4
> +CONFIG_DYNAMIC_PHYSICAL_MASK=y
> +CONFIG_PGTABLE_LEVELS=5
>   CONFIG_CC_HAS_SANE_STACKPROTECTOR=y
> -- 
> 
> Probably CONFIG_SLUB and CONFIG_SLUB_DEBUG should be used.

Used your profile and this still does not happen :(