Hi Peter,
0day kernel testing robot got the below dmesg and the first bad commit is
git://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git sched/core
commit 645566620ce8feea0970122c4a23907aa217d7f0
Author: Peter Zijlstra <pet...@infradead.org>
AuthorDate: Fri May 15 17:43:34 2015 +0200
Commit: Peter Zijlstra <pet...@infradead.org>
CommitDate: Tue Jun 2 12:01:40 2015 +0200
sched: Fix a race between __kthread_bind() and sched_setaffinity()
Because sched_setscheduler() checks p->flags & PF_NO_SETAFFINITY
without locks, a caller might observe an old value and race with the
set_cpus_allowed_ptr() call from __kthread_bind() and effectively undo
it.
__kthread_bind()
do_set_cpus_allowed()
<SYSCALL>
sched_setaffinity()
if (p->flags &
PF_NO_SETAFFINITIY)
set_cpus_allowed_ptr()
p->flags |= PF_NO_SETAFFINITY
Fix the issue by putting everything under the regular scheduler locks.
This also closes a hole in the serialization of
task_struct::{nr_,}cpus_allowed.
Cc: dedeki...@gmail.com
Cc: mgor...@suse.de
Cc: rost...@goodmis.org
Cc: juri.le...@arm.com
Cc: Oleg Nesterov <o...@redhat.com>
Cc: mi...@kernel.org
Cc: r...@redhat.com
Acked-by: Tejun Heo <t...@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <pet...@infradead.org>
Link: http://lkml.kernel.org/r/20150515154833.545640...@infradead.org
+----------------------------------------------------+------------+------------+------------+
| | cfd0d66561 | 645566620c
| 86da5c5884 |
+----------------------------------------------------+------------+------------+------------+
| boot_successes | 150 | 2
| 9 |
| boot_failures | 0 | 9
| 3 |
| WARNING:at_kernel/kthread.c:#__kthread_bind_mask() | 0 | 9
| 3 |
| backtrace:rescuer_thread | 0 | 9
| 3 |
+----------------------------------------------------+------------+------------+------------+
[ 2.425398] tun: (C) 1999-2004 Max Krasnyansky <m...@qualcomm.com>
[ 2.427338] pcnet32: pcnet32.c:v1.35 21.Apr.2008 tsbog...@alpha.franken.de
[ 2.442390] ------------[ cut here ]------------
[ 2.443944] WARNING: CPU: 0 PID: 10 at kernel/kthread.c:333
__kthread_bind_mask+0x34/0x6e()
[ 2.446978] Modules linked in:
[ 2.448359] CPU: 0 PID: 10 Comm: khelper Not tainted
4.1.0-rc6-00314-g6455666 #4
[ 2.450990] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
1.7.5-20140531_083030-gandalf 04/01/2014
[ 2.454132] 0000000000000009 ffff88000f643d68 ffffffff81a3df14
0000000000000b02
[ 2.470295] 0000000000000000 ffff88000f643da8 ffffffff810f308f
000000000f643da8
[ 2.503291] ffffffff8110d116 ffff88000f55d580 ffff88000f5240c0
ffff88000f4936e0
[ 2.506510] Call Trace:
[ 2.520770] [<ffffffff81a3df14>] dump_stack+0x4c/0x65
[ 2.522479] [<ffffffff810f308f>] warn_slowpath_common+0xa1/0xbb
[ 2.524334] [<ffffffff8110d116>] ? __kthread_bind_mask+0x34/0x6e
[ 2.526219] [<ffffffff810f314c>] warn_slowpath_null+0x1a/0x1c
[ 2.528069] [<ffffffff8110d116>] __kthread_bind_mask+0x34/0x6e
[ 2.529925] [<ffffffff8110d381>] kthread_bind_mask+0x13/0x15
[ 2.531738] [<ffffffff8110679d>] worker_attach_to_pool+0x39/0x7c
[ 2.546650] [<ffffffff8110866b>] rescuer_thread+0x130/0x318
[ 2.548484] [<ffffffff8110853b>] ? cancel_delayed_work_sync+0x15/0x15
[ 2.550411] [<ffffffff8110853b>] ? cancel_delayed_work_sync+0x15/0x15
[ 2.552207] [<ffffffff8110cd0f>] kthread+0xf8/0x100
[ 2.553864] [<ffffffff8110cc17>] ? kthread_create_on_node+0x184/0x184
[ 2.555795] [<ffffffff81a457c2>] ret_from_fork+0x42/0x70
[ 2.557538] [<ffffffff8110cc17>] ? kthread_create_on_node+0x184/0x184
[ 2.572520] ---[ end trace 362b92c9255ab666 ]---
[ 2.574163] ------------[ cut here ]------------
git bisect start 86da5c5884b34736ff50473372600c9324716df7
8af660e3a2d0740108df598ef757eb6b61953b0e --
git bisect bad 7629b214f83ecb8c4890ef4773492881b0fd8802 # 18:40 23-
28 Merge branch 'sched/core'
git bisect good c4cf50ed13b30a929c5538040c9f2115672c6f45 # 18:45 50+
1 Merge branch 'sched/urgent'
git bisect bad b2731dabb650c8d2dd35c787ef94fc6e48a47415 # 18:57 22-
15 Cleanup: preempt notifiers: disallow hlist_del within unsafe iteration
git bisect bad 8c224cd2989fb7138d0bb5ce40fd0c6ebe16ae2f # 19:10 5-
5 revert 095bebf61a46 ("sched/numa: Do not move past the balance point if
unbalanced")
git bisect bad 645566620ce8feea0970122c4a23907aa217d7f0 # 19:10 0-
9 sched: Fix a race between __kthread_bind() and sched_setaffinity()
git bisect good cfd0d66561af813f3595f2c53d433ea2fc11e619 # 19:13 50+
0 Merge branch 'sched/urgent'
# first bad commit: [645566620ce8feea0970122c4a23907aa217d7f0] sched: Fix a
race between __kthread_bind() and sched_setaffinity()
git bisect good cfd0d66561af813f3595f2c53d433ea2fc11e619 # 19:17 150+
0 Merge branch 'sched/urgent'
# extra tests on HEAD of peterz-queue/master
git bisect bad 86da5c5884b34736ff50473372600c9324716df7 # 19:17 0-
3 Merge branch 'perf/core'
# extra tests on tree/branch peterz-queue/sched/core
git bisect bad 84612110b39582c3da47b4bf7a287b93b9f9524a # 19:19 29-
70 sched: prevent throttle in early pick_next_task_fair
# extra tests on tree/branch linus/master
git bisect good c46a024ea5eb0165114dbbc8c82c29b7bcf66e71 # 07:08 150+
12 Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net
# extra tests on tree/branch next/master
git bisect good 0dfc0e41172cd9f50f5f6f0182081fa03c44e0e9 # 20:08 150+
11 Add linux-next specific files for 20150602
This script may reproduce the error.
----------------------------------------------------------------------------
#!/bin/bash
kernel=$1
initrd=yocto-minimal-x86_64.cgz
wget --no-clobber
https://github.com/fengguang/reproduce-kernel-bug/raw/master/initrd/$initrd
kvm=(
qemu-system-x86_64
-enable-kvm
-cpu Haswell,+smep,+smap
-kernel $kernel
-initrd $initrd
-m 256
-smp 1
-device e1000,netdev=net0
-netdev user,id=net0
-boot order=nc
-no-reboot
-watchdog i6300esb
-rtc base=localtime
-serial stdio
-display none
-monitor null
)
append=(
hung_task_panic=1
earlyprintk=ttyS0,115200
systemd.log_level=err
debug
apic=debug
sysrq_always_enabled
rcupdate.rcu_cpu_stall_timeout=100
panic=-1
softlockup_panic=1
nmi_watchdog=panic
oops=panic
load_ramdisk=2
prompt_ramdisk=0
console=ttyS0,115200
console=tty0
vga=normal
root=/dev/ram0
rw
drbd.minor_count=8
)
"${kvm[@]}" --append "${append[*]}"
----------------------------------------------------------------------------
Thanks,
Fengguang
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