linux-kernel - [PATCH 4.13 27/53] drm/atomic: Unref duplicated drm_atomic_state in drm_atomic_helper

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Date:   Mon, 16 Oct 2017 18:16:24 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Jeffy Chen <jeffy.chen@...k-chips.com>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>
Subject: [PATCH 4.13 27/53] drm/atomic: Unref duplicated drm_atomic_state in drm_atomic_helper_resume()

4.13-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Jeffy Chen <jeffy.chen@...k-chips.com>

commit 78279127253a6c36ed8829eb2b7bc28ef48d9717 upstream.

Kmemleak reported memory leak after suspend and resume:
unreferenced object 0xffffffc0e31d8880 (size 128):
  comm "bash", pid 181, jiffies 4294763583 (age 24.694s)
  hex dump (first 32 bytes):
    01 00 00 00 00 00 00 00 00 20 a2 eb c0 ff ff ff  ......... ......
    01 00 00 00 00 00 00 00 80 87 1d e3 c0 ff ff ff  ................
  backtrace:
    [<ffffffc00034bb64>] __save_stack_trace+0x48/0x6c
    [<ffffffc00034c244>] create_object+0x138/0x254
    [<ffffffc0009dd218>] kmemleak_alloc+0x58/0x8c
    [<ffffffc000346de4>] kmem_cache_alloc_trace+0x188/0x254
    [<ffffffc0005af4c0>] drm_atomic_state_alloc+0x3c/0x88
    [<ffffffc000591f0c>] drm_atomic_helper_duplicate_state+0x28/0x158
    [<ffffffc000592098>] drm_atomic_helper_suspend+0x5c/0xf0

Problem here is that we are duplicating the drm_atomic_state in
drm_atomic_helper_suspend(), but not unreference it in the resume path.

Fixes: 1494276000db ("drm/atomic-helper: Implement subsystem-level suspend/resume")
Signed-off-by: Jeffy Chen <jeffy.chen@...k-chips.com>
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171009064641.15174-1-jeffy.chen@rock-chips.com
Fixes: 0853695c3ba4 ("drm: Add reference counting to drm_atomic_state")
(cherry picked from commit 6d281b1f79e194c02125da29ea77316810261ca8)
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/gpu/drm/drm_atomic_helper.c |    1 +
 1 file changed, 1 insertion(+)

--- a/drivers/gpu/drm/drm_atomic_helper.c
+++ b/drivers/gpu/drm/drm_atomic_helper.c
@@ -2756,6 +2756,7 @@ out:
 		drm_modeset_backoff(&ctx);
 	}
 
+	drm_atomic_state_put(state);
 	drm_modeset_drop_locks(&ctx);
 	drm_modeset_acquire_fini(&ctx);