Re: [PATCH 5.15 04/42] RDMA/mlx5: Fix releasing unallocated memory in dereg MR flow

[Greg Kroah-Hartman]

On Fri, Jan 07, 2022 at 06:57:51AM +0100, Thorsten Leemhuis wrote:
> Hi Greg!
> 
> On 01.01.22 11:56, Thorsten Leemhuis wrote:
> > Hi, this is your Linux kernel regression tracker speaking.
> > 
> > On 15.12.21 18:20, Greg Kroah-Hartman wrote:
> >> From: Alaa Hleihel <alaa@xxxxxxxxxx>
> >>
> >> [ Upstream commit f0ae4afe3d35e67db042c58a52909e06262b740f ]
> >>
> >> For the case of IB_MR_TYPE_DM the mr does doesn't have a umem, even though
> >> it is a user MR. This causes function mlx5_free_priv_descs() to think that
> >> it is a kernel MR, leading to wrongly accessing mr->descs that will get
> >> wrong values in the union which leads to attempt to release resources that
> >> were not allocated in the first place.
> > 
> > TWIMC, that commit made it into 5.15.y, but is known to cause a
> > regression in v5.16-rc:
> > 
> > https://lore.kernel.org/lkml/f298db4ec5fdf7a2d1d166ca2f66020fd9397e5c.1640079962.git.leonro@xxxxxxxxxx/
> > https://lore.kernel.org/all/EEBA2D1C-F29C-4237-901C-587B60CEE113@xxxxxxxxxx/
> > 
> > A fix for mainline was posted, but got stuck afaics:
> > https://lore.kernel.org/lkml/f298db4ec5fdf7a2d1d166ca2f66020fd9397e5c.1640079962.git.leonro@xxxxxxxxxx/
> > 
> > A revert was also discussed, but not performed:
> > https://lore.kernel.org/all/20211222101312.1358616-1-maorg@xxxxxxxxxx/
> 
> I assume your scripts will catch this, nevertheless FYI:
> 
> Below patch was reverted in mainline, as it "is not the full fix and
> still causes to call traces". You likely want to revert it from v5.15.y
> as well. For details see
> 
> 4163cb3d1980 ("Revert "RDMA/mlx5: Fix releasing unallocated memory in
> dereg MR flow"")
> 
> https://git.kernel.org/torvalds/c/4163cb3d1980383220ad7043002b930995dcba33

Thanks for the heads-up, I have now queued this patch up for 5.15.y.

greg k-h