From: Ingo Molnar <mingo@kernel.org>
To: Mike Galbraith <efault@gmx.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
Thomas Gleixner <tglx@linutronix.de>,
Andrew Morton <akpm@linux-foundation.org>,
Yong Zhang <yong.zhang0@gmail.com>
Subject: Re: [patch] Re: [RFC GIT PULL] scheduler fix for autogroups
Date: Mon, 3 Dec 2012 06:36:14 +0100 [thread overview]
Message-ID: <20121203053614.GB27014@gmail.com> (raw)
In-Reply-To: <1354512325.7203.12.camel@marge.simpson.net>
* Mike Galbraith <efault@gmx.de> wrote:
> > Willing to write a changelog with the pointer to the actual
> > oops that happens due to this issue?
>
> I don't have a link, so reproduced/captured it. With
> systemd-sysvinit (bleh) installed, it's trivial to reproduce:
>
> Add echo 0 > /proc/sys/kernel/sched_autogroup_enabled to /root/.bashrc
> (or wherever), boot box, type reboot, box explodes.
>
> revert 800d4d30 sched, autogroup: Stop going ahead if autogroup is disabled
>
> Between 8323f26ce and 800d4d30, autogroup is a wreck. With both
Slightly decoded, for our human readers:
8323f26ce342 ("sched: Fix race in task_group()")
:-)
> applied, all you have to do to crash a box is disable autogroup
> during boot up, then reboot.. boom, NULL pointer dereference due
> to 800d4d30 not allowing autogroup to move things, and 8323f26ce
> making that the only way to switch runqueues.
>
> [ 202.187747] BUG: unable to handle kernel NULL pointer dereference at (null)
> [ 202.191644] IP: [<ffffffff81063ac0>] effective_load.isra.43+0x50/0x90
> [ 202.191644] PGD 220a74067 PUD 220402067 PMD 0
> [ 202.191644] Oops: 0000 [#1] SMP
> [ 202.191644] Modules linked in: nfs nfsd fscache lockd nfs_acl auth_rpcgss sunrpc exportfs bridge stp cpufreq_conservative cpufreq_ondemand cpufreq_userspace cpufreq_powersave acpi_cpufreq mperf ext3 jbd fuse nls_iso8859_1 snd_hda_codec_realtek nls_cp437 snd_hda_intel vfat fat snd_hda_codec e1000e sr_mod snd_hwdep cdrom snd_pcm sg snd_timer usb_storage snd firewire_ohci usb_libusual firewire_core soundcore uas snd_page_alloc i2c_i801 coretemp edd microcode hid_generic button crc_itu_t ipv6 autofs4 ext4 mbcache jbd2 crc16 usbhid hid sd_mod uhci_hcd ahci libahci libata rtc_cmos ehci_hcd scsi_mod thermal fan usbcore processor usb_common
> [ 202.191644] CPU 0
> [ 202.191644] Pid: 7047, comm: systemd-user-se Not tainted 3.6.8-smp #7 MEDIONPC MS-7502/MS-7502
> [ 202.191644] RIP: 0010:[<ffffffff81063ac0>] [<ffffffff81063ac0>] effective_load.isra.43+0x50/0x90
> [ 202.191644] RSP: 0018:ffff880221ddfbd8 EFLAGS: 00010086
> [ 202.191644] RAX: 0000000000000400 RBX: ffff88022621d880 RCX: 0000000000000000
> [ 202.191644] RDX: 0000000000000000 RSI: 0000000000000002 RDI: ffff880220a363a0
> [ 202.191644] RBP: ffff880221ddfbd8 R08: 0000000000000400 R09: 00000000000115c0
> [ 202.191644] R10: 0000000000000000 R11: 0000000000000400 R12: ffff8802214ed180
> [ 202.191644] R13: 00000000000003fd R14: 0000000000000000 R15: 0000000000000003
> [ 202.191644] FS: 00007f174a81c7a0(0000) GS:ffff88022fc00000(0000) knlGS:0000000000000000
> [ 202.191644] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [ 202.191644] CR2: 0000000000000000 CR3: 0000000221fad000 CR4: 00000000000007f0
> [ 202.191644] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> [ 202.191644] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
> [ 202.191644] Process systemd-user-se (pid: 7047, threadinfo ffff880221dde000, task ffff88022618b3a0)
> [ 202.191644] Stack:
> [ 202.191644] ffff880221ddfc88 ffffffff81063d55 0000000000000400 00000000000115c0
> [ 202.191644] ffff88022235c218 ffffffff814ef9e8 ffffea0000000000 ffff88022621d880
> [ 202.191644] ffff880227007200 ffffffff00000003 0000000000000010 0000000000018f38
> [ 202.191644] Call Trace:
> [ 202.191644] [<ffffffff81063d55>] select_task_rq_fair+0x255/0x780
> [ 202.191644] [<ffffffff810607e6>] try_to_wake_up+0x156/0x2c0
> [ 202.191644] [<ffffffff8106098b>] wake_up_state+0xb/0x10
> [ 202.191644] [<ffffffff81044f88>] signal_wake_up+0x28/0x40
> [ 202.191644] [<ffffffff81045406>] complete_signal+0x1d6/0x250
> [ 202.191644] [<ffffffff810455f0>] __send_signal+0x170/0x310
> [ 202.191644] [<ffffffff810457d0>] send_signal+0x40/0x80
> [ 202.191644] [<ffffffff81046257>] do_send_sig_info+0x47/0x90
> [ 202.191644] [<ffffffff8104649a>] group_send_sig_info+0x4a/0x70
> [ 202.191644] [<ffffffff810465ba>] kill_pid_info+0x3a/0x60
> [ 202.191644] [<ffffffff81047ac7>] sys_kill+0x97/0x1a0
> [ 202.191644] [<ffffffff810ebc10>] ? vfs_read+0x120/0x160
> [ 202.191644] [<ffffffff810ebc95>] ? sys_read+0x45/0x90
> [ 202.191644] [<ffffffff8134bde2>] system_call_fastpath+0x16/0x1b
> [ 202.191644] Code: 49 0f af 41 50 31 d2 49 f7 f0 48 83 f8 01 48 0f 46 c6 48 2b 07 48 8b bf 40 01 00 00 48 85 ff 74 3a 45 31 c0 48 8b 8f 50 01 00 00 <48> 8b 11 4c 8b 89 80 00 00 00 49 89 d2 48 01 d0 45 8b 59 58 4c
> [ 202.191644] RIP [<ffffffff81063ac0>] effective_load.isra.43+0x50/0x90
> [ 202.191644] RSP <ffff880221ddfbd8>
> [ 202.191644] CR2: 0000000000000000
>
> Signed-off-by: Mike Galbraith <efault@gmx.de>
> Cc: Yong Zhang <yong.zhang0@gmail.com>
> Cc: stable@vger.kernel.org
Thanks Mike!
Acked-by: Ingo Molnar <mingo@kernel.org>
Ingo
prev parent reply other threads:[~2012-12-03 5:36 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-12-01 11:16 [RFC GIT PULL] scheduler fix for autogroups Ingo Molnar
2012-12-01 21:16 ` Linus Torvalds
2012-12-01 21:44 ` Ingo Molnar
2012-12-01 21:47 ` Ingo Molnar
2012-12-01 22:03 ` Linus Torvalds
2012-12-02 7:34 ` Mike Galbraith
2012-12-02 8:21 ` Mike Galbraith
2012-12-02 19:27 ` Ingo Molnar
2012-12-02 19:36 ` Linus Torvalds
2012-12-03 5:25 ` [patch] " Mike Galbraith
2012-12-03 5:36 ` Ingo Molnar [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20121203053614.GB27014@gmail.com \
--to=mingo@kernel.org \
--cc=a.p.zijlstra@chello.nl \
--cc=akpm@linux-foundation.org \
--cc=efault@gmx.de \
--cc=linux-kernel@vger.kernel.org \
--cc=tglx@linutronix.de \
--cc=torvalds@linux-foundation.org \
--cc=yong.zhang0@gmail.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.