Hi, the fix is already in PeterZ queue, it will go to mainline soon.
03.11.2014, 17:54, "Fengguang Wu" <[email protected]>: > Greetings, > > 0day kernel testing robot got the below dmesg and the first bad commit is > > git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master > commit eeb61e53ea19be0c4015b00b2e8b3b2185436f2b > Author: Kirill Tkhai <[email protected]> > AuthorDate: Mon Oct 27 14:18:25 2014 +0400 > Commit: Ingo Molnar <[email protected]> > CommitDate: Tue Oct 28 10:45:59 2014 +0100 > > sched: Fix race between task_group and sched_task_group > > The race may happen when somebody is changing task_group of a forking > task. > Child's cgroup is the same as parent's after dup_task_struct() (there just > memory copying). Also, cfs_rq and rt_rq are the same as parent's. > > But if parent changes its task_group before it's called > cgroup_post_fork(), > we do not reflect this situation on child. Child's cfs_rq and rt_rq remain > the same, while child's task_group changes in cgroup_post_fork(). > > To fix this we introduce fork() method, which calls sched_move_task() > directly. > This function changes sched_task_group on appropriate (also its logic has > no problem with freshly created tasks, so we shouldn't introduce something > special; we are able just to use it). > > Possibly, this decides the Burke Libbey's problem: > https://lkml.org/lkml/2014/10/24/456 > > Signed-off-by: Kirill Tkhai <[email protected]> > Signed-off-by: Peter Zijlstra (Intel) <[email protected]> > Cc: Linus Torvalds <[email protected]> > Link: http://lkml.kernel.org/r/1414405105.19914.169.camel@tkhai > Signed-off-by: Ingo Molnar <[email protected]> > > +------------------------------------------------+-----------+------------+---------------+ > | | v3.18-rc2 | eeb61e53ea | > next-20141031 | > +------------------------------------------------+-----------+------------+---------------+ > | boot_successes | 60 | 0 | 0 > | > | boot_failures | 0 | 20 | > 11 | > | INFO:suspicious_RCU_usage | 0 | 20 | > 11 | > | backtrace:do_fork | 0 | 20 | > 11 | > | WARNING:at_kernel/sched/core.c:__might_sleep() | 0 | 0 | > 11 | > | backtrace:rfcomm_run | 0 | 0 | > 11 | > | WARNING:CPU:#PID:#at/kbuild/src/smo | 0 | 0 | 1 > | > | BUG:kernel_boot_hang | 0 | 0 | 1 > | > +------------------------------------------------+-----------+------------+---------------+ > > [ 0.086529] debug: unmapping init [mem > 0xffffffff82607000-0xffffffff82609fff] > [ 0.090115] > [ 0.090782] =============================== > [ 0.091842] [ INFO: suspicious RCU usage. ] > [ 0.092000] 3.18.0-rc2-00001-geeb61e5 #7 Not tainted > [ 0.092000] ------------------------------- > [ 0.092000] kernel/sched/core.c:7408 suspicious rcu_dereference_check() > usage! > [ 0.092000] > [ 0.092000] other info that might help us debug this: > [ 0.092000] > [ 0.092000] > [ 0.092000] rcu_scheduler_active = 1, debug_locks = 0 > [ 0.092000] 2 locks held by swapper/0/0: > [ 0.092000] #0: (&p->pi_lock){......}, at: [<ffffffff810b8d96>] > task_rq_lock+0x30/0xaa > [ 0.092000] #1: (&rq->lock){-.....}, at: [<ffffffff810b8db8>] > task_rq_lock+0x52/0xaa > [ 0.092000] > [ 0.092000] stack backtrace: > [ 0.092000] CPU: 0 PID: 0 Comm: swapper/0 Not tainted > 3.18.0-rc2-00001-geeb61e5 #7 > [ 0.092000] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 > [ 0.092000] 0000000000000001 ffffffff819dbcb8 ffffffff815e2acd > 000000000000182c > [ 0.092000] ffffffff819f85c0 ffffffff819dbce8 ffffffff810d1774 > ffff880013510000 > [ 0.092000] ffff8800139de180 ffff880013528000 0000000000800300 > ffffffff819dbd48 > [ 0.092000] Call Trace: > [ 0.092000] [<ffffffff815e2acd>] dump_stack+0x4e/0x68 > [ 0.092000] [<ffffffff810d1774>] lockdep_rcu_suspicious+0x107/0x110 > [ 0.092000] [<ffffffff810bf887>] sched_move_task+0xda/0x17b > [ 0.092000] [<ffffffff810bf945>] cpu_cgroup_fork+0x9/0xb > [ 0.092000] [<ffffffff8110c301>] cgroup_post_fork+0x9b/0xaa > [ 0.092000] [<ffffffff8109c1bd>] copy_process+0x17e5/0x1832 > [ 0.092000] [<ffffffff815def62>] ? rest_init+0x136/0x136 > [ 0.092000] [<ffffffff8109c367>] do_fork+0x8a/0x243 > [ 0.092000] [<ffffffff8109c541>] kernel_thread+0x21/0x23 > [ 0.092000] [<ffffffff815dee4a>] rest_init+0x1e/0x136 > [ 0.092000] [<ffffffff82520fb5>] start_kernel+0x4ba/0x4c7 > [ 0.092000] [<ffffffff82520120>] ? early_idt_handlers+0x120/0x120 > [ 0.092000] [<ffffffff825204de>] x86_64_start_reservations+0x2a/0x2c > [ 0.092000] [<ffffffff825205e6>] x86_64_start_kernel+0x106/0x115 > [ 0.096042] Getting VERSION: 1050014 > [ 0.097061] Getting VERSION: 1050014 > [ 0.098000] Getting ID: 0 > > git bisect start 4fbe40970dc154aaeeda0584aab8913fc073127b > cac7f2429872d3733dc3f9915857b1691da2eb2f -- > git bisect good fd2e6bbbe5b2e8f6d8ea6a28b614ec5c1c8b5a62 # 23:14 20+ > 0 Merge remote-tracking branch 'hwmon-staging/hwmon-next' > git bisect good ab6af24617af5f94df5185611f1eb39432d49292 # 01:33 20+ > 0 Merge remote-tracking branch 'spi/for-next' > git bisect bad f5ef810eb87c283118797ea33778c5b3c937ad29 # 02:08 0- > 3 Merge remote-tracking branch 'staging/staging-next' > git bisect bad 50247251e8b6078b491b5fb54dc31c24867f5930 # 02:47 0- > 9 Merge remote-tracking branch 'rcu/rcu/next' > git bisect bad 6a91cd724c20352f8cdc2a73c0649bae71897ed8 # 03:27 0- > 7 Merge remote-tracking branch 'edac-amd/for-next' > git bisect bad d7a8d245f2ffb9adde1a7121e5ab86eed8d03584 # 03:39 0- > 4 Merge remote-tracking branch 'tip/auto-latest' > git bisect good 26c2d2b39128adba276d140eefa2745591b88536 # 09:46 20+ > 0 i386/audit: stop scribbling on the stack frame > git bisect bad 3427445afd26bd2395f29241319283a93f362cd0 # 11:03 0- > 1 sched: Exclude cond_resched() from nested sleep test > git bisect bad 1a43a14a5bd9c32dbd7af35e35a5afa703944bcb # 11:39 0- > 2 sched: Fix schedule_tail() to disable preemption > git bisect bad f3a7e1a9c464a32ee186ab91388313c82e7ce018 # 12:38 0- > 1 sched/dl: Fix preemption checks > git bisect bad 1effd9f19324efb05fccc7421530e11a52db0278 # 12:55 0- > 1 sched/numa: Fix unsafe get_task_struct() in task_numa_assign() > git bisect bad 64be6f1f5f710f5995d41caf8a1767fe6d2b5a87 # 15:30 0- > 3 sched/deadline: Don't replenish from a !SCHED_DEADLINE entity > git bisect bad eeb61e53ea19be0c4015b00b2e8b3b2185436f2b # 17:18 0- > 1 sched: Fix race between task_group and sched_task_group > # first bad commit: [eeb61e53ea19be0c4015b00b2e8b3b2185436f2b] sched: Fix > race between task_group and sched_task_group > git bisect good cac7f2429872d3733dc3f9915857b1691da2eb2f # 17:31 60+ > 0 Linux 3.18-rc2 > git bisect bad 4fbe40970dc154aaeeda0584aab8913fc073127b # 17:31 0- > 11 Add linux-next specific files for 20141031 > git bisect bad 0df1f2487d2f0d04703f142813d53615d62a1da4 # 20:17 0- > 3 Linux 3.18-rc3 > git bisect bad a641d0e16b552f986e8c4a8735e66a1443a769cf # 21:44 0- > 3 Add linux-next specific files for 20141103 > > 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 $initrd > -m 320 > -smp 1 > -net nic,vlan=1,model=e1000 > -net user,vlan=1 > -boot order=nc > -no-reboot > -watchdog i6300esb > -rtc base=localtime > -serial stdio > -display none > -monitor null > ) > > append=( > hung_task_panic=1 > earlyprintk=ttyS0,115200 > debug > apic=debug > sysrq_always_enabled > rcupdate.rcu_cpu_stall_timeout=100 > panic=-1 > softlockup_panic=1 > nmi_watchdog=panic > oops=panic > load_ramdisk=2 > prompt_ramdisk=0 > console=ttyS0,115200 > console=tty0 > vga=normal > root=/dev/ram0 > rw > drbd.minor_count=8 > ) > > "${kvm[@]}" --append "${append[*]}" > ---------------------------------------------------------------------------- > > Thanks, > Fengguang > , > > _______________________________________________ > LKP mailing list > [email protected] -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
