linux-kernel - Re: [PATCH RFC V2 0/6] rxe_map_mr

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Message-ID: <c736ddff-8523-463a-aa9a-3c8542486d69@linux.dev>
Date:   Mon, 6 Nov 2023 21:58:03 +0800
From:   Zhu Yanjun <yanjun.zhu@...ux.dev>
To:     "Zhijian Li (Fujitsu)" <lizhijian@...itsu.com>,
        "zyjzyj2000@...il.com" <zyjzyj2000@...il.com>,
        "jgg@...pe.ca" <jgg@...pe.ca>, "leon@...nel.org" <leon@...nel.org>,
        "linux-rdma@...r.kernel.org" <linux-rdma@...r.kernel.org>
Cc:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "rpearsonhpe@...il.com" <rpearsonhpe@...il.com>,
        "Daisuke Matsuda (Fujitsu)" <matsuda-daisuke@...itsu.com>,
        "bvanassche@....org" <bvanassche@....org>,
        "yi.zhang@...hat.com" <yi.zhang@...hat.com>
Subject: Re: [PATCH RFC V2 0/6] rxe_map_mr_sg() fix cleanup and refactor

在 2023/11/6 12:07, Zhijian Li (Fujitsu) 写道:
> 
> 
> On 03/11/2023 21:00, Zhu Yanjun wrote:
>> 在 2023/11/3 17:55, Li Zhijian 写道:
>>> I don't collect the Reviewed-by to the patch1-2 this time, since i
>>> think we can make it better.
>>>
>>> Patch1-2: Fix kernel panic[1] and benifit to make srp work again.
>>>             Almost nothing change from V1.
>>> Patch3-5: cleanups # newly add
>>> Patch6: make RXE support PAGE_SIZE aligned mr # newly add, but not fully tested
>>>
>>> My bad arm64 mechine offten hangs when doing blktests even though i use the
>>> default siw driver.
>>>
>>> - nvme and ULPs(rtrs, iser) always registers 4K mr still don't supported yet.
>>
>> Zhijian
>>
>> Please read carefully the whole discussion about this problem. You will find a lot of valuable suggestions, especially suggestions from Jason.
> 
> Okay, i will read it again. If you can tell me which thread, that would be better.
> 
> 
>>
>>   From the whole discussion, it seems that the root cause is very clear.
>> We need to fix this prolem. Please do not send this kind of commits again.
>>
> 
> Let's think about what's our goal first.
> 
> - 1) Fix the panic[1] and only support PAGE_SIZE MR
> - 2) support PAGE_SIZE aligned MR
> - 3) support any page_size MR.
> 
> I'm sorry i'm not familiar with the linux MM subsystem. It seem it's safe/correct to access
> address/memory across pages start from the return of kmap_loca_page(page).
> In other words, 2) is already native supported, right?

Yes. Please read the comments from Jason, Leon and Bart. They shared a 
lot of good advice. From them, we can know the root cause and how to fix 
this problem.

Good Luck.

Zhu Yanjun

> 
> I get totally confused now.
> 
> 
> 
>> Zhu Yanjun
>>
>>>
>>> [1] https://lore.kernel.org/all/CAHj4cs9XRqE25jyVw9rj9YugffLn5+f=1znaBEnu1usLOciD+g@mail.gmail.com/T/
>>>
>>> Li Zhijian (6):
>>>     RDMA/rxe: RDMA/rxe: don't allow registering !PAGE_SIZE mr
>>>     RDMA/rxe: set RXE_PAGE_SIZE_CAP to PAGE_SIZE
>>>     RDMA/rxe: remove unused rxe_mr.page_shift
>>>     RDMA/rxe: Use PAGE_SIZE and PAGE_SHIFT to extract address from
>>>       page_list
>>>     RDMA/rxe: cleanup rxe_mr.{page_size,page_shift}
>>>     RDMA/rxe: Support PAGE_SIZE aligned MR
>>>
>>>    drivers/infiniband/sw/rxe/rxe_mr.c    | 80 ++++++++++++++++-----------
>>>    drivers/infiniband/sw/rxe/rxe_param.h |  2 +-
>>>    drivers/infiniband/sw/rxe/rxe_verbs.h |  9 ---
>>>    3 files changed, 48 insertions(+), 43 deletions(-)
>>>