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Message-ID: <a50530974d05fb9a625b4bf6fbf531035161f443.camel@collabora.com>
Subject: Re: [PATCH v3,1/2] media: mediatek: vcodec: adding lock to protect
 decoder context list
From: Nicolas Dufresne <nicolas.dufresne@collabora.com>
To: Yunfei Dong <yunfei.dong@mediatek.com>, =?ISO-8859-1?Q?N=EDcolas?= "F .
 R . A . Prado" <nfraprado@collabora.com>, Hans Verkuil
 <hverkuil-cisco@xs4all.nl>, AngeloGioacchino Del Regno
 <angelogioacchino.delregno@collabora.com>, Benjamin Gaignard
 <benjamin.gaignard@collabora.com>, Nathan Hebert <nhebert@chromium.org>, 
 Irui Wang <irui.wang@mediatek.com>
Cc: Hsin-Yi Wang <hsinyi@chromium.org>, Fritz Koenig
 <frkoenig@chromium.org>,  Daniel Vetter <daniel@ffwll.ch>, Steve Cho
 <stevecho@chromium.org>, linux-media@vger.kernel.org, 
 devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, 
 linux-arm-kernel@lists.infradead.org, linux-mediatek@lists.infradead.org, 
 Project_Global_Chrome_Upstream_Group@mediatek.com, Steve Cho
 <stevecho@google.com>
Date: Mon, 26 Feb 2024 14:39:00 -0500
In-Reply-To: <20240222092609.31382-2-yunfei.dong@mediatek.com>
References: <20240222092609.31382-1-yunfei.dong@mediatek.com>
	 <20240222092609.31382-2-yunfei.dong@mediatek.com>
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Hi,

Le jeudi 22 f=C3=A9vrier 2024 =C3=A0 17:26 +0800, Yunfei Dong a =C3=A9crit=
=C2=A0:
> The ctx_list will be deleted when scp getting unexpected behavior, then t=
he
> ctx_list->next will be NULL, the kernel driver maybe access NULL pointer =
in
> function vpu_dec_ipi_handler when going through each context, then reboot=
.
>=20
> Need to add lock to protect the ctx_list to make sure the ctx_list->next =
isn't
> NULL pointer.

The cited crash no longer occurs for me, but it still sometimes crashes whi=
le
the SCP being rebooted. I think this patch can still go in, as it overall
improves the situation.

Meanwhile, here's my stress test using GStreamer and stream downloaded by
fluster. I call this script few times this way as it does not always crash.=
 The
test just keep starting decode sessions and terminate them after 2 seconds.=
 It
is highly parallel. Using too low number does not reproduce the crash, usin=
g too
high number leads to alloc failure, which wasn't the goal of this test.

/mtk-vcodec-crash.sh 100

Script code:
***
#!/bin/bash

test() {
	gst-launch-1.0 --no-fault filesrc location=3DTILES_B_Cisco_1.bin ! h265par=
se ! v4l2slh265dec ! fakevideosink &
	pid=3D$!

	sleep 2
	kill $pid
}

for i in $(seq 1 $1)
do
	test &
done

wait
***

The kernel Crash:
[   93.261248] Unable to handle kernel NULL pointer dereference at virtual
address 0000000000000008
[   93.270056] Mem abort info:
[   93.272880]   ESR =3D 0x0000000096000004
[   93.276804]   EC =3D 0x25: DABT (current EL), IL =3D 32 bits
[   93.282233]   SET =3D 0, FnV =3D 0
[   93.285372]   EA =3D 0, S1PTW =3D 0
[   93.288561]   FSC =3D 0x04: level 0 translation fault
[   93.293493] Data abort info:
[   93.296424]   ISV =3D 0, ISS =3D 0x00000004, ISS2 =3D 0x00000000
[   93.301920]   CM =3D 0, WnR =3D 0, TnD =3D 0, TagAccess =3D 0
[   93.306977]   GCS =3D 0, Overlay =3D 0, DirtyBit =3D 0, Xs =3D 0
[   93.312321] user pgtable: 4k pages, 48-bit VAs, pgdp=3D0000000168daf000
[   93.318790] [0000000000000008] pgd=3D0000000000000000, p4d=3D00000000000=
00000
[   93.325588] Internal error: Oops: 0000000096000004 [#1] PREEMPT SMP
[   93.331842] Modules linked in: mt7921e mt7921_common mt792x_lib
mt76_connac_lib mt76 mac80211 btusb btintel mtk_vcodec_dec_hw btmtk btrtl
mtk_vcodec_dec btbcm cfg80211 bluetooth snd_sof_mt8195 mtk_vcodec_enc
mtk_adsp_common uvcvideo v4l2_vp9 snd_sof_xtensa_dsp v4l2_h264 mtk_vcodec_d=
bgfs
snd_sof_of snd_sof ecdh_generic mtk_vcodec_common ecc uvc elan_i2c
videobuf2_vmalloc crct10dif_ce cros_ec_lid_angle cros_ec_sensors snd_sof_ut=
ils
cros_ec_sensors_core cros_usbpd_logger cros_usbpd_charger fuse ip_tables ip=
v6
[   93.376652] CPU: 5 PID: 3210 Comm: h265parse0:sink Tainted: G        W  =
   =20
6.8.0-rc4-next-20240212+ #14
[   93.386463] Hardware name: Acer Tomato (rev3 - 4) board (DT)
[   93.392107] pstate: 80400009 (Nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=
=3D--)
[   93.399054] pc : vcodec_vpu_send_msg+0x4c/0x190 [mtk_vcodec_dec]
[   93.405058] lr : vcodec_send_ap_ipi+0x78/0x170 [mtk_vcodec_dec]
[   93.410968] sp : ffff80008750bc20
[   93.414269] x29: ffff80008750bc20 x28: ffff1299f6d70000 x27: 00000000000=
00000
[   93.421391] x26: 0000000000000000 x25: 0000000000000000 x24: 00000000000=
00000
[   93.428512] x23: ffff80008750bc98 x22: 000000000000a003 x21: ffffd45c4cf=
ae000
[   93.435632] x20: 0000000000000010 x19: ffff1299fd668310 x18: 00000000000=
0001a
[   93.442753] x17: 000000040044ffff x16: ffffd45cb15dc648 x15: 00000000000=
00000
[   93.449874] x14: ffff1299c08da1c0 x13: ffffd45cb1f87a10 x12: ffffd45cb2f=
5fe80
[   93.456995] x11: 0000000000000001 x10: 0000000000001b30 x9 : ffffd45c4d1=
2b488
[   93.464116] x8 : 1fffe25339380d81 x7 : 0000000000000001 x6 : ffff1299c9c=
06c00
[   93.471236] x5 : 0000000000000132 x4 : 0000000000000000 x3 : 00000000000=
00000
[   93.478358] x2 : 0000000000000010 x1 : ffff80008750bc98 x0 : 00000000000=
00000
[   93.485479] Call trace:
[   93.487914]  vcodec_vpu_send_msg+0x4c/0x190 [mtk_vcodec_dec]
[   93.493563]  vcodec_send_ap_ipi+0x78/0x170 [mtk_vcodec_dec]
[   93.499125]  vpu_dec_deinit+0x1c/0x30 [mtk_vcodec_dec]
[   93.504254]  vdec_hevc_slice_deinit+0x30/0x98 [mtk_vcodec_dec]
[   93.510076]  vdec_if_deinit+0x38/0x68 [mtk_vcodec_dec]
[   93.515205]  mtk_vcodec_dec_release+0x20/0x40 [mtk_vcodec_dec]
[   93.521027]  fops_vcodec_release+0x64/0x118 [mtk_vcodec_dec]
[   93.526677]  v4l2_release+0x7c/0x100
[   93.530245]  __fput+0x80/0x2d8
[   93.533292]  __fput_sync+0x58/0x70
[   93.536681]  __arm64_sys_close+0x40/0x90
[   93.540590]  invoke_syscall+0x50/0x128
[   93.544329]  el0_svc_common.constprop.0+0x48/0xf0
[   93.549020]  do_el0_svc+0x24/0x38
[   93.552323]  el0_svc+0x38/0xd8
[   93.555367]  el0t_64_sync_handler+0xc0/0xc8
[   93.559537]  el0t_64_sync+0x1a8/0x1b0
[   93.563189] Code: d503201f f9401660 b900127f b900227f (f9400400)=20
[   93.569268] ---[ end trace 0000000000000000 ]---