From: Quanyang Wang quanyang.wang@windriver.com
When running xrandr to change resolution of DP, the kmemleak as below can be observed:
unreferenced object 0xffff00080a351000 (size 256): comm "Xorg", pid 248, jiffies 4294899614 (age 19.960s) hex dump (first 32 bytes): 98 a0 bc 01 08 00 ff ff 01 00 00 00 00 00 00 00 ................ ff ff ff ff 00 00 00 00 00 00 00 00 00 00 00 00 ................ backtrace: [<00000000e0bd0f69>] kmemleak_alloc+0x30/0x40 [<00000000cde2f318>] kmem_cache_alloc+0x3d4/0x588 [<0000000088ea9bd7>] drm_atomic_helper_setup_commit+0x84/0x5f8 [<000000002290a264>] drm_atomic_helper_commit+0x58/0x388 [<00000000f6ea78c3>] drm_atomic_commit+0x4c/0x60 [<00000000c8e0725e>] drm_atomic_connector_commit_dpms+0xe8/0x110 [<0000000020ade187>] drm_mode_obj_set_property_ioctl+0x1b0/0x450 [<00000000918206d6>] drm_connector_property_set_ioctl+0x3c/0x68 [<000000008d51e7a5>] drm_ioctl_kernel+0xc4/0x118 [<000000002a819b75>] drm_ioctl+0x214/0x448 [<000000008ca4e588>] __arm64_sys_ioctl+0xa8/0xf0 [<0000000034e15a35>] el0_svc_common.constprop.0+0x74/0x190 [<000000001b93d916>] do_el0_svc+0x24/0x90 [<00000000ce9230e0>] el0_svc+0x14/0x20 [<00000000e3607d82>] el0_sync_handler+0xb0/0xb8 [<000000003e79c15f>] el0_sync+0x174/0x180
This is because there is a scenario that a drm_crtc_commit commit is allocated but not freed. The drm subsystem require/release references to a CRTC commit by calling drm_crtc_commit_get/put, and when drm_crtc_commit_put find that commit.ref.refcount is zero, it will call __drm_crtc_commit_free to free this CRTC commit. Among these drm_crtc_commit_get/put pairs, there is a drm_crtc_commit_get in drm_atomic_helper_setup_commit as below:
... new_crtc_state->event->base.completion = &commit->flip_done; new_crtc_state->event->base.completion_release = release_crtc_commit; drm_crtc_commit_get(commit); ...
This reference to the CRTC commit should be released at the function release_crtc_commit by calling e->completion_release(e->completion) in drm_send_event_locked. So we need to call drm_send_event_locked at two places: handling vblank event in the irq handler and the crtc disable helper. But in zynqmp_disp_crtc_atomic_disable, it only marks the flip is done and not call drm_crtc_commit_put. This result that the refcount of this commit is always non-zero and this commit will never be freed.
Since the function drm_crtc_send_vblank_event has operations both sending a flip_done signal and releasing reference to the CRTC commit, let's use it instead.
Signed-off-by: Quanyang Wang quanyang.wang@windriver.com --- drivers/gpu/drm/xlnx/zynqmp_disp.c | 15 +++++++-------- 1 file changed, 7 insertions(+), 8 deletions(-)
diff --git a/drivers/gpu/drm/xlnx/zynqmp_disp.c b/drivers/gpu/drm/xlnx/zynqmp_disp.c index 68cc4ffff969..ee7657a48e6a 100644 --- a/drivers/gpu/drm/xlnx/zynqmp_disp.c +++ b/drivers/gpu/drm/xlnx/zynqmp_disp.c @@ -1396,19 +1396,11 @@ static void zynqmp_disp_enable(struct zynqmp_disp *disp) */ static void zynqmp_disp_disable(struct zynqmp_disp *disp) { - struct drm_crtc *crtc = &disp->crtc; - zynqmp_disp_audio_disable(&disp->audio);
zynqmp_disp_avbuf_disable_audio(&disp->avbuf); zynqmp_disp_avbuf_disable_channels(&disp->avbuf); zynqmp_disp_avbuf_disable(&disp->avbuf); - - /* Mark the flip is done as crtc is disabled anyway */ - if (crtc->state->event) { - complete_all(crtc->state->event->base.completion); - crtc->state->event = NULL; - } }
static inline struct zynqmp_disp *crtc_to_disp(struct drm_crtc *crtc) @@ -1499,6 +1491,13 @@ zynqmp_disp_crtc_atomic_disable(struct drm_crtc *crtc,
drm_crtc_vblank_off(&disp->crtc);
+ spin_lock_irq(&crtc->dev->event_lock); + if (crtc->state->event) { + drm_crtc_send_vblank_event(crtc, crtc->state->event); + crtc->state->event = NULL; + } + spin_unlock_irq(&crtc->dev->event_lock); + clk_disable_unprepare(disp->pclk); pm_runtime_put_sync(disp->dev); }
On Tue, Feb 02, 2021 at 02:41:21PM +0800, quanyang.wang@windriver.com wrote:
From: Quanyang Wang quanyang.wang@windriver.com
When running xrandr to change resolution of DP, the kmemleak as below can be observed:
unreferenced object 0xffff00080a351000 (size 256): comm "Xorg", pid 248, jiffies 4294899614 (age 19.960s) hex dump (first 32 bytes): 98 a0 bc 01 08 00 ff ff 01 00 00 00 00 00 00 00 ................ ff ff ff ff 00 00 00 00 00 00 00 00 00 00 00 00 ................ backtrace: [<00000000e0bd0f69>] kmemleak_alloc+0x30/0x40 [<00000000cde2f318>] kmem_cache_alloc+0x3d4/0x588 [<0000000088ea9bd7>] drm_atomic_helper_setup_commit+0x84/0x5f8 [<000000002290a264>] drm_atomic_helper_commit+0x58/0x388 [<00000000f6ea78c3>] drm_atomic_commit+0x4c/0x60 [<00000000c8e0725e>] drm_atomic_connector_commit_dpms+0xe8/0x110 [<0000000020ade187>] drm_mode_obj_set_property_ioctl+0x1b0/0x450 [<00000000918206d6>] drm_connector_property_set_ioctl+0x3c/0x68 [<000000008d51e7a5>] drm_ioctl_kernel+0xc4/0x118 [<000000002a819b75>] drm_ioctl+0x214/0x448 [<000000008ca4e588>] __arm64_sys_ioctl+0xa8/0xf0 [<0000000034e15a35>] el0_svc_common.constprop.0+0x74/0x190 [<000000001b93d916>] do_el0_svc+0x24/0x90 [<00000000ce9230e0>] el0_svc+0x14/0x20 [<00000000e3607d82>] el0_sync_handler+0xb0/0xb8 [<000000003e79c15f>] el0_sync+0x174/0x180
This is because there is a scenario that a drm_crtc_commit commit is allocated but not freed. The drm subsystem require/release references to a CRTC commit by calling drm_crtc_commit_get/put, and when drm_crtc_commit_put find that commit.ref.refcount is zero, it will call __drm_crtc_commit_free to free this CRTC commit. Among these drm_crtc_commit_get/put pairs, there is a drm_crtc_commit_get in drm_atomic_helper_setup_commit as below:
... new_crtc_state->event->base.completion = &commit->flip_done; new_crtc_state->event->base.completion_release = release_crtc_commit; drm_crtc_commit_get(commit); ...
This reference to the CRTC commit should be released at the function release_crtc_commit by calling e->completion_release(e->completion) in drm_send_event_locked. So we need to call drm_send_event_locked at two places: handling vblank event in the irq handler and the crtc disable helper. But in zynqmp_disp_crtc_atomic_disable, it only marks the flip is done and not call drm_crtc_commit_put. This result that the refcount of this commit is always non-zero and this commit will never be freed.
Since the function drm_crtc_send_vblank_event has operations both sending a flip_done signal and releasing reference to the CRTC commit, let's use it instead.
Signed-off-by: Quanyang Wang quanyang.wang@windriver.com
Yeah that's the way to do it, not the hack. Thanks for your patch, I'll push it to drm-misc-fixes with Cc: stable@vger.kernel.org
Cheers, Daniel
drivers/gpu/drm/xlnx/zynqmp_disp.c | 15 +++++++-------- 1 file changed, 7 insertions(+), 8 deletions(-)
diff --git a/drivers/gpu/drm/xlnx/zynqmp_disp.c b/drivers/gpu/drm/xlnx/zynqmp_disp.c index 68cc4ffff969..ee7657a48e6a 100644 --- a/drivers/gpu/drm/xlnx/zynqmp_disp.c +++ b/drivers/gpu/drm/xlnx/zynqmp_disp.c @@ -1396,19 +1396,11 @@ static void zynqmp_disp_enable(struct zynqmp_disp *disp) */ static void zynqmp_disp_disable(struct zynqmp_disp *disp) {
struct drm_crtc *crtc = &disp->crtc;
zynqmp_disp_audio_disable(&disp->audio);
zynqmp_disp_avbuf_disable_audio(&disp->avbuf); zynqmp_disp_avbuf_disable_channels(&disp->avbuf); zynqmp_disp_avbuf_disable(&disp->avbuf);
/* Mark the flip is done as crtc is disabled anyway */
if (crtc->state->event) {
complete_all(crtc->state->event->base.completion);crtc->state->event = NULL;}
}
static inline struct zynqmp_disp *crtc_to_disp(struct drm_crtc *crtc) @@ -1499,6 +1491,13 @@ zynqmp_disp_crtc_atomic_disable(struct drm_crtc *crtc,
drm_crtc_vblank_off(&disp->crtc);
- spin_lock_irq(&crtc->dev->event_lock);
- if (crtc->state->event) {
drm_crtc_send_vblank_event(crtc, crtc->state->event);crtc->state->event = NULL;- }
- spin_unlock_irq(&crtc->dev->event_lock);
- clk_disable_unprepare(disp->pclk); pm_runtime_put_sync(disp->dev);
}
2.25.1
dri-devel@lists.freedesktop.org
-
Daniel Vetter -
quanyang.wang＠windriver.com