FAILED: patch "[PATCH] drm/amd/display: check dc_state_create_copy() for NULL in" failed to apply to 5.15-stable tree

[<gregkh@linuxfoundation.org>]

The patch below does not apply to the 5.15-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-5.15.y
git checkout FETCH_HEAD
git cherry-pick -x 015e72cde567d2450e282c2790773463156b2d0a
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2026100558-hardness-compare-fb18@gregkh' --subject-prefix 'PATCH 5.15.y' 'HEAD^..'

Possible dependencies:



thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 015e72cde567d2450e282c2790773463156b2d0a Mon Sep 17 00:00:00 2001
From: Jiangshan Yi <yijiangshan@kylinos.cn>
Date: Fri, 4 Sep 2026 17:18:17 +0800
Subject: [PATCH] drm/amd/display: check dc_state_create_copy() for NULL in
 dm_suspend

dc_state_create_copy() can return NULL on allocation failure.
dm_suspend() only conditionally skips dm_gpureset_toggle_interrupts()
and continues execution, returning success.  dm_resume() then
dereferences the NULL cached_dc_state in link_enc_cfg_copy() and the
following dc_state->stream_count loop, crashing during GPU reset
recovery.

Return -ENOMEM immediately if the copy fails, so the caller aborts
suspend instead of leaving a NULL cached state for resume.

Fixes: 8092aa3ab8f7 ("drm/amd/display: Add null checker before passing variables")
Reviewed-by: George Zhang <george.zhang@amd.com>
Signed-off-by: Jiangshan Yi <yijiangshan@kylinos.cn>
Tested-by: Dan Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
(cherry picked from commit 84b6d7932fdd2857795a257f9f258562a3cddcab)
Cc: stable@vger.kernel.org

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
index 91fdf3de7202..e0485d76dc59 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -1582,9 +1582,14 @@ static int dm_suspend(struct amdgpu_ip_block *ip_block)
 		dc_allow_idle_optimizations(adev->dm.dc, false);
 
 		dm->cached_dc_state = dc_state_create_copy(dm->dc->current_state);
+		if (!dm->cached_dc_state) {
+			drm_err(adev_to_drm(adev),
+				"Failed to allocate cached DC state during suspend\n");
+			mutex_unlock(&dm->dc_lock);
+			return -ENOMEM;
+		}
 
-		if (dm->cached_dc_state)
-			dm_gpureset_toggle_interrupts(adev, dm->cached_dc_state, false);
+		dm_gpureset_toggle_interrupts(adev, dm->cached_dc_state, false);
 
 		res = amdgpu_dm_commit_zero_streams(dm->dc);
 		if (res != DC_OK) {