Message-ID: <CACT4Y+YKmhJ2eBe0+WmRHs_yNmuAc6r-x5FQi+QAtT=LPdS4tg@mail.gmail.com>
Date:   Wed, 27 Jan 2021 19:35:25 +0100
From:   Dmitry Vyukov <dvyukov@...gle.com>
To:     Hillf Danton <hdanton@...a.com>
Cc:     syzbot <syzbot+e74a6857f2d0efe3ad81@...kaller.appspotmail.com>,
        John Fastabend <john.fastabend@...il.com>,
        Martin KaFai Lau <kafai@...com>, kpsingh@...nel.org,
        LKML <linux-kernel@...r.kernel.org>,
        netdev <netdev@...r.kernel.org>,
        syzkaller-bugs <syzkaller-bugs@...glegroups.com>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>
Subject: Re: upstream test error: INFO: trying to register non-static key in nsim_get_stats64

On Wed, Jan 27, 2021 at 1:24 PM Hillf Danton <hdanton@...a.com> wrote:
>
> On Wed, 27 Jan 2021 10:07:24 +0100 Dmitry Vyukov <dvyukov@...gle.com> wrote:
> >On Wed, Jan 27, 2021 at 6:45 AM Hillf Danton <hdanton@...a.com> wrote:
> >>
> >> Tue, 26 Jan 2021 11:46:24 -0800
> >> > syzbot found the following issue on:
> >> >
> >> > HEAD commit:    c7230a48 Merge tag 'spi-fix-v5.11-rc5' of git://git.kernel..
> >> > git tree:       upstream
> >> > console output: https://syzkaller.appspot.com/x/log.txt?x=17731f94d00000
> >> > kernel config:  https://syzkaller.appspot.com/x/.config?x=9c312983a0475388
> >> > dashboard link: https://syzkaller.appspot.com/bug?extid=e74a6857f2d0efe3ad81
> >> > userspace arch: arm
> >> >
> >> > IMPORTANT: if you fix the issue, please add the following tag to the commit:
> >> > Reported-by: syzbot+e74a6857f2d0efe3ad81@...kaller.appspotmail.com
> >> >
> >> > batman_adv: batadv0: Not using interface batadv_slave_1 (retrying later): interface not active
> >> > device hsr_slave_0 entered promiscuous mode
> >> > device hsr_slave_1 entered promiscuous mode
> >> >
> >> > INFO: trying to register non-static key.
> >> > the code is fine but needs lockdep annotation.
> >> > turning off the locking correctness validator.
> >> > CPU: 0 PID: 4695 Comm: syz-executor.0 Not tainted 5.11.0-rc5-syzkaller #0
> >> > Hardware name: ARM-Versatile Express
> >> > Backtrace:
> >> > [<826fc5b8>] (dump_backtrace) from [<826fc82c>] (show_stack+0x18/0x1c arch/arm/kernel/traps.c:252)
> >> > [<826fc814>] (show_stack) from [<8270d1f8>] (__dump_stack lib/dump_stack.c:79 [inline])
> >> > [<826fc814>] (show_stack) from [<8270d1f8>] (dump_stack+0xa8/0xc8 lib/dump_stack.c:120)
> >> > [<8270d150>] (dump_stack) from [<802bf9c0>] (assign_lock_key kernel/locking/lockdep.c:935 [inline])
> >> > [<8270d150>] (dump_stack) from [<802bf9c0>] (register_lock_class+0xabc/0xb68 kernel/locking/lockdep.c:1247)
> >> > [<802bef04>] (register_lock_class) from [<802baa2c>] (__lock_acquire+0x84/0x32d4 kernel/locking/lockdep.c:4711)
> >> > [<802ba9a8>] (__lock_acquire) from [<802be840>] (lock_acquire.part.0+0xf0/0x554 kernel/locking/lockdep.c:5442)
> >> > [<802be750>] (lock_acquire.part.0) from [<802bed10>] (lock_acquire+0x6c/0x74 kernel/locking/lockdep.c:5415)
> >> > [<802beca4>] (lock_acquire) from [<81560548>] (seqcount_lockdep_reader_access include/linux/seqlock.h:103 [inline])
> >> > [<802beca4>] (lock_acquire) from [<81560548>] (__u64_stats_fetch_begin include/linux/u64_stats_sync.h:164 [inline])
> >> > [<802beca4>] (lock_acquire) from [<81560548>] (u64_stats_fetch_begin include/linux/u64_stats_sync.h:175 [inline])
> >> > [<802beca4>] (lock_acquire) from [<81560548>] (nsim_get_stats64+0xdc/0xf0 drivers/net/netdevsim/netdev.c:70)
> >> > [<8156046c>] (nsim_get_stats64) from [<81e2efa0>] (dev_get_stats+0x44/0xd0 net/core/dev.c:10405)
> >> > [<81e2ef5c>] (dev_get_stats) from [<81e53204>] (rtnl_fill_stats+0x38/0x120 net/core/rtnetlink.c:1211)
> >> > [<81e531cc>] (rtnl_fill_stats) from [<81e59d58>] (rtnl_fill_ifinfo+0x6d4/0x148c net/core/rtnetlink.c:1783)
> >> > [<81e59684>] (rtnl_fill_ifinfo) from [<81e5ceb4>] (rtmsg_ifinfo_build_skb+0x9c/0x108 net/core/rtnetlink.c:3798)
> >> > [<81e5ce18>] (rtmsg_ifinfo_build_skb) from [<81e5d0ac>] (rtmsg_ifinfo_event net/core/rtnetlink.c:3830 [inline])
> >> > [<81e5ce18>] (rtmsg_ifinfo_build_skb) from [<81e5d0ac>] (rtmsg_ifinfo_event net/core/rtnetlink.c:3821 [inline])
> >> > [<81e5ce18>] (rtmsg_ifinfo_build_skb) from [<81e5d0ac>] (rtmsg_ifinfo+0x44/0x70 net/core/rtnetlink.c:3839)
> >> > [<81e5d068>] (rtmsg_ifinfo) from [<81e45c2c>] (register_netdevice+0x664/0x68c net/core/dev.c:10103)
> >> > [<81e455c8>] (register_netdevice) from [<815608bc>] (nsim_create+0xf8/0x124 drivers/net/netdevsim/netdev.c:317)
> >> > [<815607c4>] (nsim_create) from [<81561184>] (__nsim_dev_port_add+0x108/0x188 drivers/net/netdevsim/dev.c:941)
> >> > [<8156107c>] (__nsim_dev_port_add) from [<815620d8>] (nsim_dev_port_add_all drivers/net/netdevsim/dev.c:990 [inline])
> >> > [<8156107c>] (__nsim_dev_port_add) from [<815620d8>] (nsim_dev_probe+0x5cc/0x750 drivers/net/netdevsim/dev.c:1119)
> >> > [<81561b0c>] (nsim_dev_probe) from [<815661dc>] (nsim_bus_probe+0x10/0x14 drivers/net/netdevsim/bus.c:287)
> >> > [<815661cc>] (nsim_bus_probe) from [<811724c0>] (really_probe+0x100/0x50c drivers/base/dd.c:554)
> >> > [<811723c0>] (really_probe) from [<811729c4>] (driver_probe_device+0xf8/0x1c8 drivers/base/dd.c:740)
> >> > [<811728cc>] (driver_probe_device) from [<81172fe4>] (__device_attach_driver+0x8c/0xf0 drivers/base/dd.c:846)
> >> > [<81172f58>] (__device_attach_driver) from [<8116fee0>] (bus_for_each_drv+0x88/0xd8 drivers/base/bus.c:431)
> >> > [<8116fe58>] (bus_for_each_drv) from [<81172c6c>] (__device_attach+0xdc/0x1d0 drivers/base/dd.c:914)
> >> > [<81172b90>] (__device_attach) from [<8117305c>] (device_initial_probe+0x14/0x18 drivers/base/dd.c:961)
> >> > [<81173048>] (device_initial_probe) from [<81171358>] (bus_probe_device+0x90/0x98 drivers/base/bus.c:491)
> >> > [<811712c8>] (bus_probe_device) from [<8116e77c>] (device_add+0x320/0x824 drivers/base/core.c:3109)
> >> > [<8116e45c>] (device_add) from [<8116ec9c>] (device_register+0x1c/0x20 drivers/base/core.c:3182)
> >> > [<8116ec80>] (device_register) from [<81566710>] (nsim_bus_dev_new drivers/net/netdevsim/bus.c:336 [inline])
> >> > [<8116ec80>] (device_register) from [<81566710>] (new_device_store+0x178/0x208 drivers/net/netdevsim/bus.c:215)
> >> > [<81566598>] (new_device_store) from [<8116fcb4>] (bus_attr_store+0x2c/0x38 drivers/base/bus.c:122)
> >> > [<8116fc88>] (bus_attr_store) from [<805b4b8c>] (sysfs_kf_write+0x48/0x54 fs/sysfs/file.c:139)
> >> > [<805b4b44>] (sysfs_kf_write) from [<805b3c90>] (kernfs_fop_write_iter+0x128/0x1ec fs/kernfs/file.c:296)
> >> > [<805b3b68>] (kernfs_fop_write_iter) from [<804d22fc>] (call_write_iter include/linux/fs.h:1901 [inline])
> >> > [<805b3b68>] (kernfs_fop_write_iter) from [<804d22fc>] (new_sync_write fs/read_write.c:518 [inline])
> >> > [<805b3b68>] (kernfs_fop_write_iter) from [<804d22fc>] (vfs_write+0x3dc/0x57c fs/read_write.c:605)
> >> > [<804d1f20>] (vfs_write) from [<804d2604>] (ksys_write+0x68/0xec fs/read_write.c:658)
> >> > [<804d259c>] (ksys_write) from [<804d2698>] (__do_sys_write fs/read_write.c:670 [inline])
> >> > [<804d259c>] (ksys_write) from [<804d2698>] (sys_write+0x10/0x14 fs/read_write.c:667)
> >> > [<804d2688>] (sys_write) from [<80200060>] (ret_fast_syscall+0x0/0x2c arch/arm/mm/proc-v7.S:64)
> >>
> >> Init u64 stats for aa32.
> >>
> >>
> >> --- a/drivers/net/netdevsim/netdev.c
> >> +++ b/drivers/net/netdevsim/netdev.c
> >> @@ -296,6 +296,7 @@ nsim_create(struct nsim_dev *nsim_dev, s
> >>         dev_net_set(dev, nsim_dev_net(nsim_dev));
> >>         ns = netdev_priv(dev);
> >>         ns->netdev = dev;
> >> +       u64_stats_init(&ns->syncp);
> >>         ns->nsim_dev = nsim_dev;
> >>         ns->nsim_dev_port = nsim_dev_port;
> >>         ns->nsim_bus_dev = nsim_dev->nsim_bus_dev;
> >
> >Hi Hillf,
> >
> Hi Dmitry,
>
> >Thanks for looking into it.
> >This would be good to fix asap upstream because it boot-breaks 32-bit
> >arches (arm32). Do you mind sending a proper patch?
> >
> I'd like to do that but the barrier is, you see,
>
> 1/ I could not test it because I dont have (or access to) such a device,
> 2/ if the diff makes sense, anyone can feel free to prepare a patch and
> send it out to the maintainer because I prefer Cc much more than sob.
>
> That is it. Simple and pure.

I've run syzkaller with this patch and the warning goes away, so you may add:
Tested-by: Dmitry Vyukov <dvyukov@...gle.com>

Just in case, syzbot uses qemu-system-arm to test arm32 on x86_64. So
if you have a typical x86_64 machine, you may test this. I will
document more details soon.

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