linux-kernel - Re: WARNING: suspicious RCU usage in rds_loop_conn

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Date:   Mon, 12 Feb 2018 11:09:51 -0500
From:   Sowmini Varadhan <sowmini.varadhan@...cle.com>
To:     syzbot <syzbot+da36cb8a23beedb61503@...kaller.appspotmail.com>
Cc:     davem@...emloft.net, linux-kernel@...r.kernel.org,
        linux-rdma@...r.kernel.org, netdev@...r.kernel.org,
        rds-devel@....oracle.com, santosh.shilimkar@...cle.com,
        syzkaller-bugs@...glegroups.com
Subject: Re: WARNING: suspicious RCU usage in rds_loop_conn_alloc

> rcu_scheduler_active = 2, debug_locks = 1
> 1 lock held by syzkaller563791/4086:
>  #0:  (rcu_read_lock){....}, at: [<00000000bf5db0e6>]
> __rds_conn_create+0xe46/0x1b50 net/rds/connection.c:218
> 

the rcu_read_lock() was added by ebeeb1ad9b. After we add that,
everything in the rcu read critical section needs to use GFP_ATOMIC
to avoid sleeping. I'll look into this fix.

--Sowmini