linux-kernel - [PATCH v2] drm/atomic: Unref duplicated drm_atomic_state in drm_atomic_helper

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Date:   Mon,  9 Oct 2017 14:46:41 +0800
From:   Jeffy Chen <jeffy.chen@...k-chips.com>
To:     linux-kernel@...r.kernel.org
Cc:     Jeffy Chen <jeffy.chen@...k-chips.com>,
        Daniel Vetter <daniel.vetter@...el.com>,
        Jani Nikula <jani.nikula@...ux.intel.com>,
        dri-devel@...ts.freedesktop.org, David Airlie <airlied@...ux.ie>,
        Sean Paul <seanpaul@...omium.org>
Subject: [PATCH v2] drm/atomic: Unref duplicated drm_atomic_state in drm_atomic_helper_resume()

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>
---

Changes in v2:
Unref duplicated drm_atomic_state in drm_atomic_helper_resume() instead
of specific drivers.

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

diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
index 01c34bc5b5b0..4a262380c631 100644
--- a/drivers/gpu/drm/drm_atomic_helper.c
+++ b/drivers/gpu/drm/drm_atomic_helper.c
@@ -3052,6 +3052,7 @@ int drm_atomic_helper_resume(struct drm_device *dev,
 		drm_modeset_backoff(&ctx);
 	}
 
+	drm_atomic_state_put(state);
 	drm_modeset_drop_locks(&ctx);
 	drm_modeset_acquire_fini(&ctx);
 
-- 
2.11.0