linux-kernel - Re: [syzbot] [net?] WARNING in __linkwatch_sync

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Message-ID: <20250613165636.2fcdffa9@kernel.org>
Date: Fri, 13 Jun 2025 16:56:36 -0700
From: Jakub Kicinski <kuba@...nel.org>
To: Stanislav Fomichev <stfomichev@...il.com>
Cc: syzbot <syzbot+b8c48ea38ca27d150063@...kaller.appspotmail.com>,
 davem@...emloft.net, edumazet@...gle.com, horms@...nel.org,
 linux-kernel@...r.kernel.org, netdev@...r.kernel.org, pabeni@...hat.com,
 syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [net?] WARNING in __linkwatch_sync_dev (2)

On Thu, 12 Jun 2025 18:09:02 -0700 Stanislav Fomichev wrote:
> Where linkwatch_do_dev (potentially called from ethtool_op_get_link and
> bond_check_dev_link) might trigger ipv6 address assignment so I'm not
> sure how this all supposed to work under rcu and without rtnl lock.

Yeah, linkwatch seems to also try to allocate memory with GFP_KERNEL.

> Tentatively (untested uncompiled):

I think miimon recheck period may be rather frequent, but given 
the above going back to rtnl is probably the sanest way out.