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Date:   Thu, 7 May 2020 06:31:25 +1000
From:   Stephen Rothwell <sfr@canb.auug.org.au>
To:     Amol Grover <frextrite@gmail.com>
Cc:     Qian Cai <cai@lca.pw>, Dmitry Vyukov <dvyukov@google.com>,
        Madhuparna Bhowmik <madhuparnabhowmik10@gmail.com>,
        syzbot <syzbot+1519f497f2f9f08183c6@syzkaller.appspotmail.com>,
        David Miller <davem@davemloft.net>, kuba@kernel.org,
        Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>,
        LKML <linux-kernel@vger.kernel.org>,
        netdev <netdev@vger.kernel.org>,
        syzkaller-bugs <syzkaller-bugs@googlegroups.com>,
        Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>,
        Linux-Next Mailing List <linux-next@vger.kernel.org>,
        "paul E. McKenney" <paulmck@kernel.org>,
        "Joel Fernandes (Google)" <joel@joelfernandes.org>,
        James Morris <jmorris@namei.org>,
        "Serge E . Hallyn" <serge@hallyn.com>
Subject: Re: linux-next boot error: WARNING: suspicious RCU usage in
 ipmr_get_table
Message-ID: <20200507063125.79827a7f@canb.auug.org.au>
In-Reply-To: <20200506153941.GA16135@kernel-dev-lenovo>
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        <34558B83-103E-4205-8D3D-534978D5A498@lca.pw>
        <20200506153941.GA16135@kernel-dev-lenovo>
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Hi all,

On Wed, 6 May 2020 21:09:41 +0530 Amol Grover <frextrite@gmail.com> wrote:
>
> On Tue, Apr 28, 2020 at 09:56:59AM -0400, Qian Cai wrote:
> >=20
> > >> =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D
> > >> WARNING: suspicious RCU usage
> > >> 5.7.0-rc3-next-20200428-syzkaller #0 Not tainted
> > >> -----------------------------
> > >> security/integrity/evm/evm_main.c:231 RCU-list traversed in non-read=
er section!! =20
> >=20
> > Ditto.
> >  =20
> > >>=20
> > >> other info that might help us debug this:
> > >>=20
> > >>=20
> > >> rcu_scheduler_active =3D 2, debug_locks =3D 1
> > >> 2 locks held by systemd/1:
> > >> #0: ffff888098dfa450 (sb_writers#8){.+.+}-{0:0}, at: sb_start_write =
include/linux/fs.h:1659 [inline]
> > >> #0: ffff888098dfa450 (sb_writers#8){.+.+}-{0:0}, at: mnt_want_write+=
0x3a/0xb0 fs/namespace.c:354
> > >> #1: ffff8880988e8310 (&type->i_mutex_dir_key#6){++++}-{3:3}, at: ino=
de_lock include/linux/fs.h:799 [inline]
> > >> #1: ffff8880988e8310 (&type->i_mutex_dir_key#6){++++}-{3:3}, at: vfs=
_setxattr+0x92/0xf0 fs/xattr.c:219
> > >>=20
> > >> stack backtrace:
> > >> CPU: 0 PID: 1 Comm: systemd Not tainted 5.7.0-rc3-next-20200428-syzk=
aller #0
> > >> Hardware name: Google Google Compute Engine/Google Compute Engine, B=
IOS Google 01/01/2011
> > >> Call Trace:
> > >> __dump_stack lib/dump_stack.c:77 [inline]
> > >> dump_stack+0x18f/0x20d lib/dump_stack.c:118
> > >> evm_protected_xattr+0x1c2/0x210 security/integrity/evm/evm_main.c:231
> > >> evm_protect_xattr.isra.0+0xb6/0x3d0 security/integrity/evm/evm_main.=
c:318
> > >> evm_inode_setxattr+0xc4/0xf0 security/integrity/evm/evm_main.c:387
> > >> security_inode_setxattr+0x18f/0x200 security/security.c:1297
> > >> vfs_setxattr+0xa7/0xf0 fs/xattr.c:220
> > >> setxattr+0x23d/0x330 fs/xattr.c:451
> > >> path_setxattr+0x170/0x190 fs/xattr.c:470
> > >> __do_sys_setxattr fs/xattr.c:485 [inline]
> > >> __se_sys_setxattr fs/xattr.c:481 [inline]
> > >> __x64_sys_setxattr+0xc0/0x160 fs/xattr.c:481
> > >> do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:295
> > >> entry_SYSCALL_64_after_hwframe+0x49/0xb3
> > >> RIP: 0033:0x7fe46005e67a
> > >> Code: 48 8b 0d 21 18 2b 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f=
 84 00 00 00 00 00 0f 1f 44 00 00 49 89 ca b8 bc 00 00 00 0f 05 <48> 3d 01 =
f0 ff ff 73 01 c3 48 8b 0d ee 17 2b 00 f7 d8 64 89 01 48
> > >> RSP: 002b:00007fffef423568 EFLAGS: 00000246 ORIG_RAX: 00000000000000=
bc
> > >> RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fe46005e67a
> > >> RDX: 00007fffef4235e0 RSI: 0000556ea53ddf9b RDI: 0000556ea6766760
> > >> RBP: 0000556ea53ddf9b R08: 0000000000000000 R09: 0000000000000030
> > >> R10: 0000000000000020 R11: 0000000000000246 R12: 00007fffef4235e0
> > >> R13: 0000000000000020 R14: 0000000000000000 R15: 0000556ea6751700
> > >>=20
> > >> security/device_cgroup.c:357 RCU-list traversed in non-reader sectio=
n!! =20
> >=20
> > https://lore.kernel.org/lkml/20200406105950.GA2285@workstation-kernel-d=
ev/
> >=20
> > The same story. The patch had been ignored for a while.
> >  =20
>=20
> Thank you for reminding! I will resend the patches and try to get them
> merged ASAP.

I have also applied the above patch to by fixes tree from today and
will remove it when a solution is applied to some other tree.

--=20
Cheers,
Stephen Rothwell

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