Re: [Ksummit-discuss] [MAINTAINER SUMMIT] Stable trees and release time

From: Sasha Levin <Alexander.Levin@microsoft.com>
To: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: James Bottomley <James.Bottomley@hansenpartnership.com>,
	Greg KH <gregkh@linuxfoundation.org>,
	"ksummit-discuss@lists.linuxfoundation.org"
	<ksummit-discuss@lists.linuxfoundation.org>
Subject: Re: [Ksummit-discuss] [MAINTAINER SUMMIT] Stable trees and release time
Date: Wed, 5 Sep 2018 20:18:51 +0000	[thread overview]
Message-ID: <20180905201848.GV16300@sasha-vm> (raw)
In-Reply-To: <20180905190902.GU16300@sasha-vm>

On Wed, Sep 05, 2018 at 03:09:02PM -0400, Sasha Levin wrote:
>On Wed, Sep 05, 2018 at 06:26:17PM +0200, Daniel Vetter wrote:
>>Note that because of fbcon and other reasons, an rmmod i915 will fail.
>>You need to enable a bunch of CONFIG_EXPERT options (with scary texts
>>and stuff) and have a script from our test suite to be able to even
>>make this happen.
>
>Hm, how does that work?
>
>On an Ubuntu 4.18 kernel I can remove i915 just by:
>
>root@jumpy:~# echo 1 > /sys/devices/pci0000\:00/0000\:00\:02.0/remove
>root@jumpy:~# sudo rmmod i915

... which apparently spews a warning and hangs the system:

[  802.065412] PCH DPLL A assertion failure (expected on, current off)
[  802.065574] WARNING: CPU: 1 PID: 804 at drivers/gpu/drm/i915/intel_dpll_mgr.c:124 assert_shared_dpll+0x106/0x120 [i915]
[  802.065576] Modules linked in: intel_rapl x86_pkg_temp_thermal intel_powerclamp kvm_intel kvm irqbypass arc4 snd_hda_codec_hdmi crct10dif_pclmul crc32_pclmul ghash_clmulni_intel pcbc iwldvm snd_hda_codec_conexant snd_hda_codec_generic mac80211 gpio_ich snd_hda_intel iwlwifi snd_hda_codec aesni_intel aes_x86_64 crypto_simd snd_hda_core cryptd glue_helper snd_hwdep input_leds intel_cstate intel_rapl_perf joydev snd_pcm serio_raw cfg80211 wmi_bmof snd_timer lpc_ich mei_me mei thinkpad_acpi nvram snd soundcore mac_hid binfmt_misc sch_fq_codel coretemp ip_tables x_tables autofs4 i915 i2c_algo_bit drm_kms_helper psmouse syscopyarea e1000e sysfillrect sysimgblt fb_sys_fops sdhci_pci ahci drm cqhci libahci sdhci wmi video
[  802.065678] CPU: 1 PID: 804 Comm: bash Not tainted 4.18.6-041806-generic #201809050847
[  802.065681] Hardware name: LENOVO 4236AT9/4236AT9, BIOS 83ET66WW (1.36 ) 10/31/2011
[  802.065769] RIP: 0010:assert_shared_dpll+0x106/0x120 [i915]
[  802.065770] Code: c7 c2 42 cc 36 c0 48 8b 83 88 00 00 00 48 89 f1 48 c7 c7 40 49 38 c0 48 0f 44 ca 45 84 e4 48 0f 45 d6 48 8b 30 e8 5c 60 7b dc <0f> 0b e9 40 ff ff ff e8 ae 5d 7b dc 66 66 2e 0f 1f 84 00 00 00 00
[  802.065883] RSP: 0018:ffffba82014d3a28 EFLAGS: 00010282
[  802.065887] RAX: 0000000000000000 RBX: ffff9a3e8977e350 RCX: 0000000000000006
[  802.065890] RDX: 0000000000000007 RSI: 0000000000000092 RDI: ffff9a3e9e2564b0
[  802.065893] RBP: ffffba82014d3ac0 R08: 0000000000000001 R09: 0000000000000341
[  802.065895] R10: 0000000000000004 R11: 0000000000000000 R12: 0000000000000001
[  802.065898] R13: 0000000000000001 R14: ffff9a3e89778000 R15: ffff9a3e8977e6b8
[  802.065902] FS:  00007fcd73414740(0000) GS:ffff9a3e9e240000(0000) knlGS:0000000000000000
[  802.065905] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  802.065908] CR2: 000055cf3a21ae00 CR3: 00000002137b4002 CR4: 00000000000606e0
[  802.065911] Call Trace:
[  802.065926]  ? __cancel_work_timer+0x110/0x190
[  802.066003]  ? intel_set_pch_fifo_underrun_reporting+0xec/0x180 [i915]
[  802.066082]  intel_disable_shared_dpll+0xa2/0x140 [i915]
[  802.066162]  intel_atomic_commit_tail+0x210/0xd10 [i915]
[  802.066244]  intel_atomic_commit+0x2b8/0x2f0 [i915]
[  802.066290]  drm_atomic_commit+0x4a/0x50 [drm]
[  802.066315]  __drm_atomic_helper_disable_all+0x190/0x1d0 [drm_kms_helper]
[  802.066335]  drm_atomic_helper_shutdown+0x5c/0xb0 [drm_kms_helper]
[  802.066397]  i915_driver_unload+0x8a/0x120 [i915]
[  802.066462]  i915_pci_remove+0x19/0x30 [i915]
[  802.066470]  pci_device_remove+0x3e/0xc0
[  802.066479]  device_release_driver_internal+0x18c/0x250
[  802.066486]  device_release_driver+0x12/0x20
[  802.066492]  pci_stop_bus_device+0x82/0xa0
[  802.066498]  pci_stop_and_remove_bus_device_locked+0x1a/0x30
[  802.066504]  remove_store+0x7c/0x90
[  802.066509]  dev_attr_store+0x1b/0x30
[  802.066515]  sysfs_kf_write+0x3b/0x50
[  802.066520]  kernfs_fop_write+0x12e/0x1b0
[  802.066526]  __vfs_write+0x3a/0x190
[  802.066533]  ? common_file_perm+0x4d/0x140
[  802.066538]  ? apparmor_file_permission+0x1a/0x20
[  802.066546]  ? security_file_permission+0x2f/0xb0
[  802.066554]  ? _cond_resched+0x19/0x30
[  802.066559]  vfs_write+0xab/0x1b0
[  802.066564]  ksys_write+0x55/0xc0
[  802.066569]  __x64_sys_write+0x1a/0x20
[  802.066576]  do_syscall_64+0x5a/0x110
[  802.066583]  entry_SYSCALL_64_after_hwframe+0x44/0xa9
[  802.066588] RIP: 0033:0x7fcd72ae9154
[  802.066589] Code: 89 02 48 c7 c0 ff ff ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 8d 05 b1 07 2e 00 8b 00 85 c0 75 13 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 54 f3 c3 66 90 41 54 55 49 89 d4 53 48 89 f5
[  802.066668] RSP: 002b:00007ffdc88ea2c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
[  802.066673] RAX: ffffffffffffffda RBX: 0000000000000002 RCX: 00007fcd72ae9154
[  802.066676] RDX: 0000000000000002 RSI: 0000561e2995ec20 RDI: 0000000000000001
[  802.066678] RBP: 0000561e2995ec20 R08: 000000000000000a R09: 0000000000000001
[  802.066681] R10: 000000000000000a R11: 0000000000000246 R12: 00007fcd72dc5760
[  802.066683] R13: 0000000000000002 R14: 00007fcd72dc12a0 R15: 00007fcd72dc0760
[  802.066689] ---[ end trace 45b9f0b00b7e9277 ]---

--
Thanks,
Sasha