Re: FAILED: patch "[PATCH] drm/amd/display: fix double memory allocation" failed to apply to 6.3-stable tree

[Greg KH <gregkh@linuxfoundation.org>]

On Sat, May 13, 2023 at 07:28:20AM -0500, Mario Limonciello wrote:
> On 5/13/23 02:20, gregkh@linuxfoundation.org wrote:
> > 
> > The patch below does not apply to the 6.3-stable tree.
> > If someone wants it applied there, or to any other stable or longterm
> > tree, then please email the backport, including the original git commit
> > id to <stable@vger.kernel.org>.
> > 
> > To reproduce the conflict and resubmit, you may use the following commands:
> > 
> > git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.3.y
> > git checkout FETCH_HEAD
> > git cherry-pick -x f5442b35e69e42015ef3082008c0d85cdcc0ca05
> > # <resolve conflicts, build, test, etc.>
> > git commit -s
> > git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2023051306-elves-dividers-01e7@gregkh' --subject-prefix 'PATCH 6.3.y' HEAD^..
> > 
> > Possible dependencies:
> > 
> > f5442b35e69e ("drm/amd/display: fix double memory allocation")
> > b5006f873b99 ("drm/amd/display: initialize link_srv in virtual env")
> > 
> > thanks,
> > 
> > greg k-h
> > 
> > ------------------ original commit in Linus's tree ------------------
> > 
> >  From f5442b35e69e42015ef3082008c0d85cdcc0ca05 Mon Sep 17 00:00:00 2001
> > From: Martin Leung <Martin.Leung@amd.com>
> > Date: Tue, 14 Mar 2023 09:27:20 -0400
> > Subject: [PATCH] drm/amd/display: fix double memory allocation
> > 
> > [Why & How]
> > when trying to fix a nullptr dereference on VMs,
> > accidentally doubly allocated memory for the non VM
> > case. removed the extra link_srv creation since
> > dc_construct_ctx is called in both VM and non VM cases
> > Also added a proper fail check for if kzalloc fails
> > 
> > Cc: stable@vger.kernel.org
> > Cc: Mario Limonciello <mario.limonciello@amd.com>
> > Reviewed-by: Leo Ma <Hanghong.Ma@amd.com>
> > Acked-by: Qingqing Zhuo <qingqing.zhuo@amd.com>
> > Signed-off-by: Martin Leung <Martin.Leung@amd.com>
> > Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
> > Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
> > 
> > diff --git a/drivers/gpu/drm/amd/display/dc/core/dc.c b/drivers/gpu/drm/amd/display/dc/core/dc.c
> > index 40f2e174c524..52564b93f7eb 100644
> > --- a/drivers/gpu/drm/amd/display/dc/core/dc.c
> > +++ b/drivers/gpu/drm/amd/display/dc/core/dc.c
> > @@ -887,7 +887,10 @@ static bool dc_construct_ctx(struct dc *dc,
> >   	}
> >   	dc->ctx = dc_ctx;
> > +
> >   	dc->link_srv = link_create_link_service();
> > +	if (!dc->link_srv)
> > +		return false;
> >   	return true;
> >   }
> > @@ -986,8 +989,6 @@ static bool dc_construct(struct dc *dc,
> >   		goto fail;
> >   	}
> > -	dc->link_srv = link_create_link_service();
> > -
> >   	dc->res_pool = dc_create_resource_pool(dc, init_params, dc_ctx->dce_version);
> >   	if (!dc->res_pool)
> >   		goto fail;
> > 
> 
> FYI -
> This particular commit didn't need to come back to any stable channels as
> the commit it fixed
> b5006f873b99 ("drm/amd/display: initialize link_srv in virtual env")
> is only present in 6.4.

Any reason why a "Fixes:" tag wasn't added here?  That would have made
it much easier to figure this all out :)

thanks,

greg k-h