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Message-ID: <20160809143450.GB11220@yexl-desktop>
Date: Tue, 9 Aug 2016 22:34:50 +0800
From: kernel test robot <xiaolong.ye@...el.com>
To: Jens Axboe <axboe@...com>
Cc: LKML <linux-kernel@...r.kernel.org>, Jens Axboe <axboe@...com>,
Jens Axboe <axboe@...nel.dk>, lkp@...org
Subject: [lkp] [writeback] 3aff5d8a15: INFO: suspicious RCU usage. ]
FYI, we noticed the following commit:
https://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux-block.git wb-buf-throttle
commit 3aff5d8a151b40d3a3a93984ebcbae4a64a40176 ("writeback: throttle buffered writeback")
in testcase: boot
on test machine: 1 threads qemu-system-x86_64 -enable-kvm -cpu IvyBridge with 360M memory
caused below changes:
+-------------------------------------------------------+------------+------------+
| | 0a4c97b401 | 3aff5d8a15 |
+-------------------------------------------------------+------------+------------+
| boot_successes | 8 | 0 |
| boot_failures | 0 | 8 |
| INFO:suspicious_RCU_usage | 0 | 8 |
| backtrace:SyS_open | 0 | 2 |
| backtrace:compat_SyS_mount | 0 | 6 |
| WARNING:at_kernel/trace/ftrace.c:#ftrace_bug | 0 | 1 |
| general_protection_fault:#[##]SMP | 0 | 1 |
| RIP:is_ftrace_trampoline | 0 | 1 |
| Kernel_panic-not_syncing:Fatal_exception_in_interrupt | 0 | 1 |
| backtrace:perf_ftrace_event_register | 0 | 1 |
| backtrace:perf_trace_init | 0 | 1 |
| backtrace:perf_tp_event_init | 0 | 1 |
| backtrace:perf_try_init_event | 0 | 1 |
| backtrace:perf_event_alloc | 0 | 1 |
| backtrace:SyS_perf_event_open | 0 | 1 |
+-------------------------------------------------------+------------+------------+
Starting udev
[ 14.537229]
[ 14.548128] ===============================
[ 14.549048] [ INFO: suspicious RCU usage. ]
[ 14.549968] 4.8.0-rc1-00008-g3aff5d8 #40 Not tainted
[ 14.550985] -------------------------------
[ 14.551911] include/linux/cgroup.h:435 suspicious rcu_dereference_check() usage!
[ 14.553839]
[ 14.553839] other info that might help us debug this:
[ 14.553839]
[ 14.555960]
[ 14.555960] rcu_scheduler_active = 1, debug_locks = 0
[ 14.557501] 4 locks held by mount/2444:
[ 14.558381] #0: (&bdev->bd_mutex){+.+.+.}, at: [<ffffffff81232ea9>] __blkdev_get+0x96/0x3d0
[ 14.560529] #1: (floppy_mutex){+.+.+.}, at: [<ffffffff81776481>] floppy_open+0x38/0x303
[ 14.562622] #2: (open_lock){+.+.+.}, at: [<ffffffff8177648f>] floppy_open+0x46/0x303
[ 14.564705] #3: (floppy_lock){......}, at: [<ffffffff81569a18>] cfq_set_request+0x6d/0x33e
[ 14.566833]
[ 14.566833] stack backtrace:
[ 14.568162] CPU: 0 PID: 2444 Comm: mount Not tainted 4.8.0-rc1-00008-g3aff5d8 #40
[ 14.569827] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Debian-1.8.2-1 04/01/2014
[ 14.571645] 0000000000000000 ffff88000e35f760 ffffffff8156f2de ffff88000cc80040
[ 14.573578] 0000000000000001 ffff88000e35f790 ffffffff810ec284 ffff88000e224008
[ 14.575520] ffff88000cc80040 0000000000000003 ffff880011378008 ffff88000e35f850
[ 14.577464] Call Trace:
[ 14.578196] [<ffffffff8156f2de>] dump_stack+0x86/0xc0
[ 14.579229] [<ffffffff810ec284>] lockdep_rcu_suspicious+0xf7/0x100
[ 14.580385] [<ffffffff81568764>] check_blkcg_changed+0x202/0x402
[ 14.581511] [<ffffffff810efd39>] ? lock_acquire+0x180/0x21b
[ 14.582585] [<ffffffff81569a18>] ? cfq_set_request+0x6d/0x33e
[ 14.583692] [<ffffffff81569a9d>] cfq_set_request+0xf2/0x33e
[ 14.584777] [<ffffffff81cea55f>] ? _raw_spin_unlock_irq+0x2c/0x3d
[ 14.585919] [<ffffffff810ee022>] ? trace_hardirqs_on_caller+0x17e/0x19a
[ 14.587121] [<ffffffff810ee04b>] ? trace_hardirqs_on+0xd/0xf
[ 14.588222] [<ffffffff81cea55f>] ? _raw_spin_unlock_irq+0x2c/0x3d
[ 14.589357] [<ffffffff8154b000>] ? ioc_create_icq+0x15b/0x172
[ 14.590446] [<ffffffff8153fa22>] elv_set_request+0x1f/0x24
[ 14.591524] [<ffffffff81543d0f>] get_request+0x5bb/0xaaf
[ 14.592582] [<ffffffff810e41be>] ? wake_up_bit+0x2a/0x2a
[ 14.593625] [<ffffffff81547635>] blk_queue_bio+0x1bd/0x4d0
[ 14.594700] [<ffffffff81545418>] generic_make_request+0xbd/0x15b
[ 14.595855] [<ffffffff815455b9>] submit_bio+0x103/0x10c
[ 14.596883] [<ffffffff817760f2>] __floppy_read_block_0+0xd4/0x11f
[ 14.598020] [<ffffffff810ee04b>] ? trace_hardirqs_on+0xd/0xf
[ 14.599117] [<ffffffff81775fd9>] ? floppy_resume+0x3f/0x3f
[ 14.600195] [<ffffffff817762dc>] floppy_revalidate+0x19f/0x1b2
[ 14.601279] [<ffffffff8123228b>] check_disk_change+0x52/0x5e
[ 14.602366] [<ffffffff817766c8>] floppy_open+0x27f/0x303
[ 14.603425] [<ffffffff81232f1b>] __blkdev_get+0x108/0x3d0
[ 14.604485] [<ffffffff812334bd>] ? blkdev_get+0x2da/0x2fe
[ 14.605533] [<ffffffff812333aa>] blkdev_get+0x1c7/0x2fe
[ 14.606574] [<ffffffff8121a900>] ? mntput+0x2d/0x2f
[ 14.607586] [<ffffffff81203f43>] ? path_put+0x1e/0x21
[ 14.608616] [<ffffffff81233514>] blkdev_get_by_path+0x33/0x69
[ 14.609707] [<ffffffff811fdfd4>] mount_bdev+0x48/0x197
[ 14.610740] [<ffffffff812b4dbb>] ? ext4_calculate_overhead+0x2bd/0x2bd
[ 14.611954] [<ffffffff812b1429>] ext4_mount+0x15/0x17
[ 14.612968] [<ffffffff811feb83>] mount_fs+0x14/0x8d
[ 14.613964] [<ffffffff81219ae7>] vfs_kern_mount+0x6b/0x133
[ 14.615038] [<ffffffff8121cb22>] do_mount+0x88c/0xb06
[ 14.616074] [<ffffffff811b9dec>] ? strndup_user+0x3f/0x6b
[ 14.617129] [<ffffffff81248e63>] compat_SyS_mount+0x185/0x1ae
[ 14.618223] [<ffffffff81001d9f>] do_int80_syscall_32+0x68/0x11a
[ 14.619350] [<ffffffff81ced0b8>] entry_INT80_compat+0x38/0x50
[ 14.683168] blk_update_request: I/O error, dev fd0, sector 0
[ 14.684284] floppy: error -5 while reading block 0
FYI, raw QEMU command line is:
qemu-system-x86_64 -enable-kvm -cpu IvyBridge -kernel /pkg/linux/x86_64-nfsroot/gcc-6/3aff5d8a151b40d3a3a93984ebcbae4a64a40176/vmlinuz-4.8.0-rc1-00008-g3aff5d8 -append 'ip=::::vm-ivb41-yocto-ia32-14::dhcp root=/dev/ram0 user=lkp job=/lkp/scheduled/vm-ivb41-yocto-ia32-14/boot-1-yocto-minimal-i386.cgz-3aff5d8a151b40d3a3a93984ebcbae4a64a40176-20160808-91612-fsj5dk-0.yaml ARCH=x86_64 kconfig=x86_64-nfsroot branch=linux-devel/devel-catchup-201608082019 commit=3aff5d8a151b40d3a3a93984ebcbae4a64a40176 BOOT_IMAGE=/pkg/linux/x86_64-nfsroot/gcc-6/3aff5d8a151b40d3a3a93984ebcbae4a64a40176/vmlinuz-4.8.0-rc1-00008-g3aff5d8 max_uptime=600 RESULT_ROOT=/result/boot/1/vm-ivb41-yocto-ia32/yocto-minimal-i386.cgz/x86_64-nfsroot/gcc-6/3aff5d8a151b40d3a3a93984ebcbae4a64a40176/0 LKP_SERVER=inn 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 systemd.log_level=err ignore_loglevel earlyprintk=ttyS0,115200 console=ttyS0,115200 console=tty0 vga=normal rw drbd.minor_count=8' -initrd /fs/sda5/initrd-vm-ivb41-yocto-ia32-14 -m 360 -smp 1 -device e1000,netdev=net0 -netdev user,id=net0 -boot order=nc -no-reboot -watchdog i6300esb -watchdog-action debug -rtc base=localtime -drive file=/fs/sda5/disk0-vm-ivb41-yocto-ia32-14,media=disk,if=virtio -pidfile /dev/shm/kboot/pid-vm-ivb41-yocto-ia32-14 -serial file:/dev/shm/kboot/serial-vm-ivb41-yocto-ia32-14 -daemonize -display none -monitor null
Thanks,
Xiaolong
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