Subject: Re: linux-next boot error: WARNING: suspicious RCU usage in ipmr_get_table

From: Stephen Rothwell <[email-masked]>
Date: Thu, 7 May 2020 06:31:25 +1000

Hi all,

On Wed, 6 May 2020 21:09:41 +0530 Amol Grover <[email-masked]> wrote:
>
> On Tue, Apr 28, 2020 at 09:56:59AM -0400, Qian Cai wrote:
> > 
> > >> =============================
> > >> 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-reader section!!  
> > 
> > Ditto.
> >   
> > >> 
> > >> other info that might help us debug this:
> > >> 
> > >> 
> > >> rcu_scheduler_active = 2, debug_locks = 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: inode_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
> > >> 
> > >> stack backtrace:
> > >> CPU: 0 PID: 1 Comm: systemd Not tainted 5.7.0-rc3-next-20200428-syzkaller #0
> > >> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS 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: 00000000000000bc
> > >> 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
> > >> 
> > >> security/device_cgroup.c:357 RCU-list traversed in non-reader section!!  
> > 
> > https://lore.kernel.org/lkml/20200406105950.GA2285@workstation-kernel-dev/
> > 
> > The same story. The patch had been ignored for a while.
> >   
> 
> 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.

-- 
Cheers,
Stephen Rothwell