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Message-ID: <CAA8Xd+9QEn0XE2pV-7fW0cBXKBSK9=oZyTaFH2urGvJLGb=gFw@mail.gmail.com>
Date: Tue, 24 Feb 2015 13:19:22 -0300
From: Gustavo Bittencourt <gbitten@...il.com>
To: Mike Galbraith <umgwanakikbuti@...il.com>
Cc: Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
linux-rt-users <linux-rt-users@...r.kernel.org>,
LKML <linux-kernel@...r.kernel.org>,
Thomas Gleixner <tglx@...utronix.de>, rostedt@...dmis.org,
John Kacur <jkacur@...hat.com>
Subject: Re: [ANNOUNCE] 3.18.7-rt2
On Tue, Feb 24, 2015 at 10:41 AM, Mike Galbraith
<umgwanakikbuti@...il.com> wrote:
> locking, ww_mutex: fix ww_mutex vs self-deadlock
>
> If the caller already holds the mutex, task_blocks_on_rt_mutex()
> returns -EDEADLK, we proceed directly to rt_mutex_handle_deadlock()
> where it's instant game over.
>
> Let ww_mutexes return EDEADLK/EALREADY as they want to instead.
>
> Signed-off-by: Mike Galbraith <umgwanakikbuti@...il.com>
> ---
> kernel/locking/rtmutex.c | 17 +++++++++++------
> 1 file changed, 11 insertions(+), 6 deletions(-)
>
> --- a/kernel/locking/rtmutex.c
> +++ b/kernel/locking/rtmutex.c
The deadlock returned after I applied this patch in v3.18.7-rt2. Here is my log:
[ 244.476210] BUG: scheduling while atomic: Xorg/1549/0x00000002
[ 244.476258] Modules linked in: ctr ccm nouveau arc4 ath9k
ath9k_common ath9k_hw ath mac80211 uvcvideo snd_hda_codec_hdmi
videobuf2_vmalloc snd_hda_codec_realtek videobuf2_memops
videobuf2_core snd_hda_codec_generic v4l2_common snd_hda_intel
videodev mxm_wmi wmi i2c_algo_bit drm_kms_helper snd_hda_controller
snd_hda_codec ttm drm snd_pcm snd_hwdep snd_seq_midi
snd_seq_midi_event snd_rawmidi intel_rapl snd_seq bnep
x86_pkg_temp_thermal cfg80211 intel_powerclamp snd_timer mei_me
snd_seq_device rfcomm snd btusb mei joydev soundcore bluetooth
serio_raw mac_hid coretemp lpc_ich sony_laptop crc32_pclmul video
parport_pc ppdev lp parport firewire_ohci psmouse ahci sdhci_pci
firewire_core r8169 libahci sdhci mii crc_itu_t
[ 244.476261] Preemption disabled at:[<c1685f5b>] rt_mutex_slowlock+0x3b/0x200
[ 244.476262]
[ 244.476263] CPU: 2 PID: 1549 Comm: Xorg Tainted: G W
3.18.7-rt2-00002-g8c033b9 #3
[ 244.476264] Hardware name: Sony Corporation VPCF215FB/VAIO, BIOS
R0200V3 02/10/2011
[ 244.476271] 00000000 00000000 f1a5fc5c c1681e38 f1968f20 f1a5fc74
c167eacf c18f581c
[ 244.476278] c1685f5b c1685f5b 00000002 f1a5fcf8 c1684a3e f1a5fcfc
c187136c 0000001d
[ 244.476287] c1adabc0 c1adabc0 00000000 f168fc00 00000038 f1968f20
f7774bc0 f1968f20
[ 244.476288] Call Trace:
[ 244.476291] [<c1681e38>] dump_stack+0x4b/0x88
[ 244.476294] [<c167eacf>] __schedule_bug+0x9e/0xac
[ 244.476297] [<c1685f5b>] ? rt_mutex_slowlock+0x3b/0x200
[ 244.476300] [<c1685f5b>] ? rt_mutex_slowlock+0x3b/0x200
[ 244.476303] [<c1684a3e>] __schedule+0x6ce/0x7a0
[ 244.476306] [<c105fb6b>] ? print_oops_end_marker+0x3b/0x40
[ 244.476308] [<c105fbff>] ? warn_slowpath_common+0x8f/0xa0
[ 244.476311] [<c167ec42>] ?
rt_mutex_handle_deadlock.isra.21.part.22+0x2f/0x48
[ 244.476313] [<c167ec42>] ?
rt_mutex_handle_deadlock.isra.21.part.22+0x2f/0x48
[ 244.476315] [<c1684b3b>] schedule+0x2b/0x90
[ 244.476318] [<c167ec59>] rt_mutex_handle_deadlock.isra.21.part.22+0x46/0x48
[ 244.476320] [<c168610d>] rt_mutex_slowlock+0x1ed/0x200
[ 244.476322] [<c10848eb>] ? get_parent_ip+0xb/0x40
[ 244.476325] [<c1686142>] __ww_mutex_lock_interruptible+0x22/0x30
[ 244.476343] [<f8ddb7fb>] nouveau_gem_ioctl_pushbuf+0x68b/0x13c0 [nouveau]
[ 244.476345] [<c132d022>] ? debug_smp_processor_id+0x12/0x20
[ 244.476348] [<c1060283>] ? unpin_current_cpu+0x13/0x60
[ 244.476365] [<f8ddb170>] ? nouveau_gem_ioctl_new+0x1d0/0x1d0 [nouveau]
[ 244.476373] [<f891d137>] drm_ioctl+0x1b7/0x510 [drm]
[ 244.476390] [<f8ddb170>] ? nouveau_gem_ioctl_new+0x1d0/0x1d0 [nouveau]
[ 244.476393] [<c132d022>] ? debug_smp_processor_id+0x12/0x20
[ 244.476395] [<c1060283>] ? unpin_current_cpu+0x13/0x60
[ 244.476397] [<c1084e40>] ? migrate_enable+0xa0/0x1c0
[ 244.476400] [<c143f6b1>] ? __pm_runtime_resume+0x41/0x50
[ 244.476417] [<f8dd2707>] nouveau_drm_ioctl+0x47/0xb0 [nouveau]
[ 244.476434] [<f8dd26c0>] ? nouveau_pmops_thaw+0x20/0x20 [nouveau]
[ 244.476436] [<c11a9e82>] do_vfs_ioctl+0x2f2/0x4f0
[ 244.476438] [<c10c5132>] ? ktime_get_ts64+0x52/0x1a0
[ 244.476441] [<c10be330>] ? __remove_hrtimer+0xd0/0xd0
[ 244.476443] [<c11aa0e0>] SyS_ioctl+0x60/0x90
[ 244.476446] [<c1687d70>] sysenter_do_call+0x12/0x12
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