linux-kernel - [PATCH 1/2] drm/atmel-hlcdc: fix memory leak from the atomic_destroy

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Message-ID: <20251024-lcd_fixes_mainlining-v1-1-79b615130dc3@microchip.com>
Date: Fri, 24 Oct 2025 18:14:52 +0200
From: Ludovic Desroches <ludovic.desroches@...rochip.com>
To: Manikandan Muralidharan <manikandan.m@...rochip.com>, "Dharma
 Balasubiramani" <dharma.b@...rochip.com>, Maarten Lankhorst
	<maarten.lankhorst@...ux.intel.com>, Maxime Ripard <mripard@...nel.org>,
	Thomas Zimmermann <tzimmermann@...e.de>, David Airlie <airlied@...il.com>,
	Simona Vetter <simona@...ll.ch>, Nicolas Ferre <nicolas.ferre@...rochip.com>,
	Alexandre Belloni <alexandre.belloni@...tlin.com>, Claudiu Beznea
	<claudiu.beznea@...on.dev>
CC: <dri-devel@...ts.freedesktop.org>, <linux-arm-kernel@...ts.infradead.org>,
	<linux-kernel@...r.kernel.org>, Ludovic Desroches
	<ludovic.desroches@...rochip.com>
Subject: [PATCH 1/2] drm/atmel-hlcdc: fix memory leak from the
 atomic_destroy_state callback

After several commits, the slab memory increases. Some drm_crtc_commit
objects are not freed. The atomic_destroy_state callback only put the
framebuffer. Use the __drm_atomic_helper_plane_destroy_state() function
to put all the objects that are no longer needed.

It has been seen after hours of usage of a graphics application or using
kmemleak:

unreferenced object 0xc63a6580 (size 64):
  comm "egt_basic", pid 171, jiffies 4294940784
  hex dump (first 32 bytes):
    40 50 34 c5 01 00 00 00 ff ff ff ff 8c 65 3a c6  @P4..........e:.
    8c 65 3a c6 ff ff ff ff 98 65 3a c6 98 65 3a c6  .e:......e:..e:.
  backtrace (crc c25aa925):
    kmemleak_alloc+0x34/0x3c
    __kmalloc_cache_noprof+0x150/0x1a4
    drm_atomic_helper_setup_commit+0x1e8/0x7bc
    drm_atomic_helper_commit+0x3c/0x15c
    drm_atomic_commit+0xc0/0xf4
    drm_atomic_helper_set_config+0x84/0xb8
    drm_mode_setcrtc+0x32c/0x810
    drm_ioctl+0x20c/0x488
    sys_ioctl+0x14c/0xc20
    ret_fast_syscall+0x0/0x54

Signed-off-by: Ludovic Desroches <ludovic.desroches@...rochip.com>
Reviewed-by: Manikandan Muralidharan <manikandan.m@...rochip.com>
---
 drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_plane.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_plane.c b/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_plane.c
index 38f60befd7d759a52d66211c2e7d49c9be235ad4..0e38587b868d5b5375fcaa5c0508e8e5690d8ff8 100644
--- a/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_plane.c
+++ b/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_plane.c
@@ -1215,8 +1215,7 @@ static void atmel_hlcdc_plane_atomic_destroy_state(struct drm_plane *p,
 			      state->dscrs[i]->self);
 	}
 
-	if (s->fb)
-		drm_framebuffer_put(s->fb);
+	__drm_atomic_helper_plane_destroy_state(s);
 
 	kfree(state);
 }

-- 
2.51.0