linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Leon Romanovsky <leon@kernel.org>
To: Thorsten Leemhuis <regressions@leemhuis.info>
Cc: Tony Lu <tonylu@linux.alibaba.com>,
	Jason Gunthorpe <jgg@nvidia.com>,
	Maor Gottlieb <maorg@nvidia.com>, Alaa Hleihel <alaa@nvidia.com>,
	Chuck Lever <chuck.lever@oracle.com>,
	linux-kernel@vger.kernel.org, linux-rdma@vger.kernel.org
Subject: Re: [PATCH rdma-rc] RDMA/mlx5: Fix dereg mr flow for kernel MRs
Date: Mon, 3 Jan 2022 20:26:24 +0200	[thread overview]
Message-ID: <YdM/0EUd3S4obWWa@unreal> (raw)
In-Reply-To: <0d897f0a-6671-bb78-21d5-e475d1db29b9@leemhuis.info>

On Mon, Jan 03, 2022 at 02:15:59PM +0100, Thorsten Leemhuis wrote:
> Hi, this is your Linux kernel regression tracker speaking.
> 
> On 03.01.22 10:51, Leon Romanovsky wrote:
> > On Wed, Dec 22, 2021 at 10:51:58AM +0800, Tony Lu wrote:
> >> On Tue, Dec 21, 2021 at 11:46:41AM +0200, Leon Romanovsky wrote:
> >>> From: Maor Gottlieb <maorg@nvidia.com>
> >>>
> >>> The cited commit moved umem into the union, hence
> >>> umem could be accessed only for user MRs. Add udata check
> >>> before access umem in the dereg flow.
> >>>
> >>> Fixes: f0ae4afe3d35 ("RDMA/mlx5: Fix releasing unallocated memory in dereg MR flow")
> >>> Tested-by: Chuck Lever <chuck.lever@oracle.com>
> >>> Signed-off-by: Maor Gottlieb <maorg@nvidia.com>
> >>> Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
> >>> ---
> >>>  drivers/infiniband/hw/mlx5/mlx5_ib.h | 2 +-
> >>>  drivers/infiniband/hw/mlx5/mr.c      | 4 ++--
> >>>  drivers/infiniband/hw/mlx5/odp.c     | 4 ++--
> >>>  3 files changed, 5 insertions(+), 5 deletions(-)
> >>>
> >>> diff --git a/drivers/infiniband/hw/mlx5/mlx5_ib.h b/drivers/infiniband/hw/mlx5/mlx5_ib.h
> >>
> >> This patch was tested and works for me in our environment for SMC. It
> >> wouldn't panic when release link and call ib_dereg_mr.
> >>
> >> Tested-by: Tony Lu <tonylu@linux.alibaba.com>
> > 
> > Thanks, unfortunately, this patch is incomplete.
> 
> Could you be a bit more verbose and give a status update? It's hard to
> follow from the outside. But according to the "Fixes: f0ae4afe3d35"
> above this was supposed to fix a regression introduced in v5.16-rc5 that
> was also reported here:
> https://lore.kernel.org/linux-rdma/9974ea8c-f1cb-aeb4-cf1b-19d37536894a@linux.alibaba.com/

The problematic commit f0ae4afe3d35 ("RDMA/mlx5: Fix releasing unallocated memory in dereg MR flow")
should be reverted https://lore.kernel.org/all/20211222101312.1358616-1-maorg@nvidia.com
and rewritten from the beginning.

There are three possible ways to rewrite that f0ae4afe3d35 commit, while
the nutshell of the problem is: "DM MR is user created verb object that
is missing very important property (umem) which is needed to distinguish
between kernel and user created objects."

The proposals are:
1. Return back to v1, which had dummy umem, so so DM memory regions will
behave as regular user created verbs object.
2. Add extra flag to is_user/is_kernel for mlx5 mr struct and update all
paths to rely on that flag.
3. Create separate dereg MR function that will treat DM differently.

We are waiting for Jason to return from vacation and express his
preference as he didn't like my preferred option #1.

Thanks

> 
> Commit f0ae4afe3d35 in fact was also backported to v5.15.y and might
> cause trouble there as well.
> 
> Should it maybe simply be reverted (and reapplied with all fixes later)
> in mainline (5.16 will likely be released in 6 days!) and v5.15.y?
> 
> Ciao, Thorsten (wearing his 'Linux kernel regression tracker' hat)
> 
> P.S.: As a Linux kernel regression tracker I'm getting a lot of reports
> on my table. I can only look briefly into most of them. Unfortunately
> therefore I sometimes will get things wrong or miss something important.
> I hope that's not the case here; if you think it is, don't hesitate to
> tell me about it in a public reply, that's in everyone's interest.
> 
> BTW, I have no personal interest in this issue, which is tracked using
> regzbot, my Linux kernel regression tracking bot
> (https://linux-regtracking.leemhuis.info/regzbot/). I'm only posting
> this mail to get things rolling again and hence don't need to be CC on
> all further activities wrt to this regression.
> 

  reply	other threads:[~2022-01-03 18:26 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-12-21  9:46 Leon Romanovsky
2021-12-22  2:51 ` Tony Lu
2022-01-03  9:51   ` Leon Romanovsky
2022-01-03 13:15     ` Thorsten Leemhuis
2022-01-03 18:26       ` Leon Romanovsky [this message]
2022-01-04  0:08         ` Jason Gunthorpe
2022-01-04 10:29         ` Thorsten Leemhuis

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=YdM/0EUd3S4obWWa@unreal \
    --to=leon@kernel.org \
    --cc=alaa@nvidia.com \
    --cc=chuck.lever@oracle.com \
    --cc=jgg@nvidia.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-rdma@vger.kernel.org \
    --cc=maorg@nvidia.com \
    --cc=regressions@leemhuis.info \
    --cc=tonylu@linux.alibaba.com \
    --subject='Re: [PATCH rdma-rc] RDMA/mlx5: Fix dereg mr flow for kernel MRs' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).