On Wed, 13 Apr 2022 at 01:36, Abhinav Kumar <quic_abhinavk@xxxxxxxxxxx> wrote: > > Hi Daniel > > On 4/8/2022 9:04 PM, Abhinav Kumar wrote: > > > > > > On 4/7/2022 4:12 PM, Rob Clark wrote: > >> On Thu, Apr 7, 2022 at 3:59 PM Abhinav Kumar > >> <quic_abhinavk@xxxxxxxxxxx> wrote: > >>> > >>> Hi Rob and Daniel > >>> > >>> On 4/7/2022 3:51 PM, Rob Clark wrote: > >>>> On Wed, Apr 6, 2022 at 6:27 PM Jessica Zhang > >>>> <quic_jesszhan@xxxxxxxxxxx> wrote: > >>>>> > >>>>> > >>>>> > >>>>> On 3/31/2022 8:20 AM, Daniel Vetter wrote: > >>>>>> The stuff never really worked, and leads to lots of fun because it > >>>>>> out-of-order frees atomic states. Which upsets KASAN, among other > >>>>>> things. > >>>>>> > >>>>>> For async updates we now have a more solid solution with the > >>>>>> ->atomic_async_check and ->atomic_async_commit hooks. Support for > >>>>>> that > >>>>>> for msm and vc4 landed. nouveau and i915 have their own commit > >>>>>> routines, doing something similar. > >>>>>> > >>>>>> For everyone else it's probably better to remove the use-after-free > >>>>>> bug, and encourage folks to use the async support instead. The > >>>>>> affected drivers which register a legacy cursor plane and don't > >>>>>> either > >>>>>> use the new async stuff or their own commit routine are: amdgpu, > >>>>>> atmel, mediatek, qxl, rockchip, sti, sun4i, tegra, virtio, and > >>>>>> vmwgfx. > >>>>>> > >>>>>> Inspired by an amdgpu bug report. > >>>>>> > >>>>>> v2: Drop RFC, I think with amdgpu converted over to use > >>>>>> atomic_async_check/commit done in > >>>>>> > >>>>>> commit 674e78acae0dfb4beb56132e41cbae5b60f7d662 > >>>>>> Author: Nicholas Kazlauskas <nicholas.kazlauskas@xxxxxxx> > >>>>>> Date: Wed Dec 5 14:59:07 2018 -0500 > >>>>>> > >>>>>> drm/amd/display: Add fast path for cursor plane updates > >>>>>> > >>>>>> we don't have any driver anymore where we have userspace expecting > >>>>>> solid legacy cursor support _and_ they are using the atomic > >>>>>> helpers in > >>>>>> their fully glory. So we can retire this. > >>>>>> > >>>>>> v3: Paper over msm and i915 regression. The complete_all is the only > >>>>>> thing missing afaict. > >>>>>> > >>>>>> v4: Fixup i915 fixup ... > >>>>>> > >>>>>> References: https://bugzilla.kernel.org/show_bug.cgi?id=199425 > >>>>>> References: > >>>>>> https://lore.kernel.org/all/20220221134155.125447-9-maxime@xxxxxxxxxx/ > >>>>>> > >>>>>> References: https://bugzilla.kernel.org/show_bug.cgi?id=199425 > >>>>>> Cc: Maxime Ripard <maxime@xxxxxxxxxx> > >>>>>> Tested-by: Maxime Ripard <maxime@xxxxxxxxxx> > >>>>>> Cc: mikita.lipski@xxxxxxx > >>>>>> Cc: Michel Dänzer <michel@xxxxxxxxxxx> > >>>>>> Cc: harry.wentland@xxxxxxx > >>>>>> Cc: Rob Clark <robdclark@xxxxxxxxx> > >>>>> > >>>>> Hey Rob, > >>>>> > >>>>> I saw your tested-by and reviewed-by tags on Patchwork. Just curious, > >>>>> what device did you test on? > >>>> > >>>> I was testing on strongbad.. v5.18-rc1 + patches (notably, revert > >>>> 80253168dbfd ("drm: of: Lookup if child node has panel or bridge") > >>>> > >>>> I think the display setup shouldn't be significantly different than > >>>> limozeen (ie. it's an eDP panel). But I didn't do much start/stop > >>>> ui.. I was mostly looking to make sure cursor movements weren't > >>>> causing fps drops ;-) > >>>> > >>>> BR, > >>>> -R > >>> > >>> start ui/ stop ui is a basic operation for us to use IGT on msm-next. > >>> So we cannot let that break. > >>> > >>> I think we need to check whats causing this splat. > >>> > >>> Can we hold back this change till then? > >> > >> Can you reproduce on v5.18-rc1 (plus 80253168dbfd)? I'm running a > >> loop of stop ui / start ui and hasn't triggered a splat yet. > >> > >> Otherwise maybe you can addr2line to figure out where it crashed? > >> > >> BR, > >> -R > > > > So this is not a crash. Its a warning splat coming from > > > > https://gitlab.freedesktop.org/drm/msm/-/blob/msm-next/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c#L785 > > > > > > Looks like the complete_commit() which should signal the event has not > > happened before the next cursor commit. > > > > Somehow this change is affecting the flow to miss the event signaling > > that the event is done. > > > > We tried a couple of approaches but couldnt still fix the warning. > > > > Will continue to check further next week. > > > >> > >>> Thanks > >>> > >>> Abhinav > > After checking this more this week, I think the current patch needs to > be changed a bit. > > So, here you are removing the complete_all part and leaving that to the > individual drivers, which is fine. > > But, you are also removing the continue part which I think seems > incorrect and causing these warnings for MSM driver. > > @@ -2135,12 +2128,6 @@ int drm_atomic_helper_setup_commit(struct > drm_atomic_state *state, > continue; > } > > - /* Legacy cursor updates are fully unsynced. */ > - if (state->legacy_cursor_update) { > - complete_all(&commit->flip_done); > - continue; > - } > - > > Thats because MSM driver thinks that if the previous crtc_state->event > was not consumed, then something went wrong and throws a warning. > > if (!new_crtc_state->event) { > commit->event = kzalloc(sizeof(*commit->event), > GFP_KERNEL); > if (!commit->event) > return -ENOMEM; > > new_crtc_state->event = commit->event; > } > > But for a cursor update, we should not or need not populate the event at > all because it is async. > > So i think we should still keep the continue, rest of the patch is fine. > > @@ -2128,6 +2128,9 @@ int drm_atomic_helper_setup_commit(struct > drm_atomic_state *state, > continue; > } > > + if (state->legacy_cursor_update) > + continue; > + > > Let me know your comments. Thanks a lot for your excellent analysis. I need to think this through some more and figure out what exactly we should be doing. -Daniel > Thanks > > Abhinav > >>>> > >>>>> I'm hitting several instances of this error when doing a start/stop ui > >>>>> on Lazor Chromebook with this patch: > >>>>> > >>>>> [ 3092.608322] CPU: 2 PID: 18579 Comm: DrmThread Tainted: G W > >>>>> 5.17.0-rc2-lockdep-00089-g7f17ab7bf567 #155 > >>>>> e5912cd286513b064a82a38938b3fdef86b079aa > >>>>> [ 3092.622880] Hardware name: Google Lazor Limozeen without > >>>>> Touchscreen > >>>>> (rev4) (DT) > >>>>> [ 3092.630492] pstate: 80400009 (Nzcv daif +PAN -UAO -TCO -DIT -SSBS > >>>>> BTYPE=--) > >>>>> [ 3092.637664] pc : dpu_crtc_atomic_flush+0x9c/0x144 > >>>>> [ 3092.642523] lr : dpu_crtc_atomic_flush+0x60/0x144 > >>>>> [ 3092.647379] sp : ffffffc00c1e3760 > >>>>> [ 3092.650805] x29: ffffffc00c1e3760 x28: ffffff80985dd800 x27: > >>>>> 0000000000000425 > >>>>> [ 3092.658164] x26: ffffff80985dc500 x25: ffffff80985ddc00 x24: > >>>>> ffffffdf8ae3b6f0 > >>>>> [ 3092.665522] x23: 0000000000000000 x22: 0000000000000000 x21: > >>>>> ffffff809b82da00 > >>>>> [ 3092.672890] x20: ffffff80840e1000 x19: ffffff80840e2000 x18: > >>>>> 0000000000001000 > >>>>> [ 3092.680255] x17: 0000000000000400 x16: 0000000000000100 x15: > >>>>> 000000000000003b > >>>>> [ 3092.687622] x14: 0000000000000000 x13: 0000000000000002 x12: > >>>>> 0000000000000003 > >>>>> [ 3092.694979] x11: ffffff8084009000 x10: 0000000000000040 x9 : > >>>>> 0000000000000040 > >>>>> [ 3092.702340] x8 : 0000000000000300 x7 : 000000000000000c x6 : > >>>>> 0000000000000004 > >>>>> [ 3092.709698] x5 : 0000000000000320 x4 : 0000000000000018 x3 : > >>>>> 0000000000000000 > >>>>> [ 3092.717056] x2 : 0000000000000000 x1 : 7bfb38b2a3a89800 x0 : > >>>>> ffffff809a1eb300 > >>>>> [ 3092.724424] Call trace: > >>>>> [ 3092.726958] dpu_crtc_atomic_flush+0x9c/0x144 > >>>>> [ 3092.731463] drm_atomic_helper_commit_planes+0x1bc/0x1c4 > >>>>> [ 3092.736944] msm_atomic_commit_tail+0x23c/0x3e0 > >>>>> [ 3092.741627] commit_tail+0x7c/0xfc > >>>>> [ 3092.745145] drm_atomic_helper_commit+0x158/0x15c > >>>>> [ 3092.749998] drm_atomic_commit+0x60/0x74 > >>>>> [ 3092.754055] drm_atomic_helper_update_plane+0x100/0x110 > >>>>> [ 3092.759449] __setplane_atomic+0x11c/0x120 > >>>>> [ 3092.763685] drm_mode_cursor_universal+0x188/0x22c > >>>>> [ 3092.768633] drm_mode_cursor_common+0x120/0x1f8 > >>>>> [ 3092.773310] drm_mode_cursor_ioctl+0x68/0x8c > >>>>> [ 3092.777721] drm_ioctl_kernel+0xe8/0x168 > >>>>> [ 3092.781770] drm_ioctl+0x320/0x370 > >>>>> [ 3092.785289] drm_compat_ioctl+0x40/0xdc > >>>>> [ 3092.789257] __arm64_compat_sys_ioctl+0xe0/0x150 > >>>>> [ 3092.794030] invoke_syscall+0x80/0x114 > >>>>> [ 3092.797905] el0_svc_common.constprop.3+0xc4/0xf8 > >>>>> [ 3092.802765] do_el0_svc_compat+0x2c/0x54 > >>>>> [ 3092.806811] el0_svc_compat+0x4c/0xe4 > >>>>> [ 3092.810598] el0t_32_sync_handler+0xc4/0xf4 > >>>>> [ 3092.814914] el0t_32_sync+0x174/0x178 > >>>>> [ 3092.818701] irq event stamp: 55940 > >>>>> [ 3092.822217] hardirqs last enabled at (55939): [<ffffffdf8ad617a4>] > >>>>> exit_to_kernel_mode+0x10c/0x11c > >>>>> [ 3092.831523] hardirqs last disabled at (55940): [<ffffffdf8ad62728>] > >>>>> el1_dbg+0x28/0x70 > >>>>> [ 3092.839577] softirqs last enabled at (55938): [<ffffffdf8a2103a8>] > >>>>> __do_softirq+0x1e8/0x480 > >>>>> [ 3092.848256] softirqs last disabled at (55923): [<ffffffdf8a28d668>] > >>>>> __irq_exit_rcu+0xdc/0x140 > >>>>> [ 3092.857022] ---[ end trace 0000000000000000 ]--- > >>>>> > >>>>> > >>>>> > >>>>> > >>>>> Thanks, > >>>>> > >>>>> Jessica Zhang > >>>>> > >>>>>> Cc: "Kazlauskas, Nicholas" <nicholas.kazlauskas@xxxxxxx> > >>>>>> Cc: Dmitry Osipenko <dmitry.osipenko@xxxxxxxxxxxxx> > >>>>>> Signed-off-by: Daniel Vetter <daniel.vetter@xxxxxxxxx> > >>>>>> --- > >>>>>> drivers/gpu/drm/drm_atomic_helper.c | 13 ------------- > >>>>>> drivers/gpu/drm/i915/display/intel_display.c | 14 ++++++++++++++ > >>>>>> drivers/gpu/drm/msm/msm_atomic.c | 2 ++ > >>>>>> 3 files changed, 16 insertions(+), 13 deletions(-) > >>>>>> > >>>>>> diff --git a/drivers/gpu/drm/drm_atomic_helper.c > >>>>>> b/drivers/gpu/drm/drm_atomic_helper.c > >>>>>> index 9603193d2fa1..a2899af82b4a 100644 > >>>>>> --- a/drivers/gpu/drm/drm_atomic_helper.c > >>>>>> +++ b/drivers/gpu/drm/drm_atomic_helper.c > >>>>>> @@ -1498,13 +1498,6 @@ drm_atomic_helper_wait_for_vblanks(struct > >>>>>> drm_device *dev, > >>>>>> int i, ret; > >>>>>> unsigned int crtc_mask = 0; > >>>>>> > >>>>>> - /* > >>>>>> - * Legacy cursor ioctls are completely unsynced, and userspace > >>>>>> - * relies on that (by doing tons of cursor updates). > >>>>>> - */ > >>>>>> - if (old_state->legacy_cursor_update) > >>>>>> - return; > >>>>>> - > >>>>>> for_each_oldnew_crtc_in_state(old_state, crtc, > >>>>>> old_crtc_state, new_crtc_state, i) { > >>>>>> if (!new_crtc_state->active) > >>>>>> continue; > >>>>>> @@ -2135,12 +2128,6 @@ int drm_atomic_helper_setup_commit(struct > >>>>>> drm_atomic_state *state, > >>>>>> continue; > >>>>>> } > >>>>>> > >>>>>> - /* Legacy cursor updates are fully unsynced. */ > >>>>>> - if (state->legacy_cursor_update) { > >>>>>> - complete_all(&commit->flip_done); > >>>>>> - continue; > >>>>>> - } > >>>>>> - > >>>>>> if (!new_crtc_state->event) { > >>>>>> commit->event = > >>>>>> kzalloc(sizeof(*commit->event), > >>>>>> GFP_KERNEL); > >>>>>> diff --git a/drivers/gpu/drm/i915/display/intel_display.c > >>>>>> b/drivers/gpu/drm/i915/display/intel_display.c > >>>>>> index d2abe0e430bf..6ca5a6e7703b 100644 > >>>>>> --- a/drivers/gpu/drm/i915/display/intel_display.c > >>>>>> +++ b/drivers/gpu/drm/i915/display/intel_display.c > >>>>>> @@ -8799,6 +8799,20 @@ static int intel_atomic_commit(struct > >>>>>> drm_device *dev, > >>>>>> intel_runtime_pm_put(&dev_priv->runtime_pm, > >>>>>> state->wakeref); > >>>>>> return ret; > >>>>>> } > >>>>>> + > >>>>>> + /* > >>>>>> + * FIXME: Cut over to (async) commit helpers instead of > >>>>>> hand-rolling > >>>>>> + * everything. > >>>>>> + */ > >>>>>> + if (state->base.legacy_cursor_update) { > >>>>>> + struct intel_crtc_state *new_crtc_state; > >>>>>> + struct intel_crtc *crtc; > >>>>>> + int i; > >>>>>> + > >>>>>> + for_each_new_intel_crtc_in_state(state, crtc, > >>>>>> new_crtc_state, i) > >>>>>> + > >>>>>> complete_all(&new_crtc_state->uapi.commit->flip_done); > >>>>>> + } > >>>>>> + > >>>>>> intel_shared_dpll_swap_state(state); > >>>>>> intel_atomic_track_fbs(state); > >>>>>> > >>>>>> diff --git a/drivers/gpu/drm/msm/msm_atomic.c > >>>>>> b/drivers/gpu/drm/msm/msm_atomic.c > >>>>>> index 1686fbb611fd..b3cfabebe5d6 100644 > >>>>>> --- a/drivers/gpu/drm/msm/msm_atomic.c > >>>>>> +++ b/drivers/gpu/drm/msm/msm_atomic.c > >>>>>> @@ -222,6 +222,8 @@ void msm_atomic_commit_tail(struct > >>>>>> drm_atomic_state *state) > >>>>>> /* async updates are limited to single-crtc > >>>>>> updates: */ > >>>>>> WARN_ON(crtc_mask != drm_crtc_mask(async_crtc)); > >>>>>> > >>>>>> + complete_all(&async_crtc->state->commit->flip_done); > >>>>>> + > >>>>>> /* > >>>>>> * Start timer if we don't already have an update > >>>>>> pending > >>>>>> * on this crtc: > >>>>>> -- > >>>>>> 2.34.1 > >>>>>> -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch
