From: David Miller <davem@davemloft.net>
To: david.lebrun@uclouvain.be
Cc: netdev@vger.kernel.org
Subject: Re: [PATCH net] ipv6: sr: fix BUG in HMAC init when preemption is enabled
Date: Tue, 10 Jan 2017 21:00:13 -0500 (EST) [thread overview]
Message-ID: <20170110.210013.2057547033044168090.davem@davemloft.net> (raw)
In-Reply-To: <1484055562-6414-1-git-send-email-david.lebrun@uclouvain.be>
From: David Lebrun <david.lebrun@uclouvain.be>
Date: Tue, 10 Jan 2017 14:39:22 +0100
> When CONFIG_PREEMPT=y, CONFIG_IPV6=m and CONFIG_SEG6_HMAC=y,
> seg6_hmac_init() is called during the initialization of the ipv6 module.
> This causes a subsequent call to smp_processor_id() with preemption
> enabled, resulting in the following trace.
...
> This patch disable BHs in seg6_hmac_init() and seg6_hmac_exit(). BHs are
> re-enabled for the call to crypto_alloc_shash. Indeed, this function might
> call try_module_get(), which cannot be called in atomic context.
>
> Signed-off-by: David Lebrun <david.lebrun@uclouvain.be>
...
> - char *ring = kzalloc(SEG6_HMAC_RING_SIZE, GFP_KERNEL);
> + char *ring = kzalloc(SEG6_HMAC_RING_SIZE, GFP_ATOMIC);
I agree with Eric that moving to GFP_ATOMIC in this spots is a major step
backwards, and that fixing the per-cpu access during this initializer
is a much better direction to go.
Thanks.
next prev parent reply other threads:[~2017-01-11 2:00 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-01-10 13:39 [PATCH net] ipv6: sr: fix BUG in HMAC init when preemption is enabled David Lebrun
2017-01-10 18:16 ` ericnetdev dumazet
2017-01-10 18:29 ` David Miller
2017-01-10 18:31 ` ericnetdev dumazet
2017-01-11 2:00 ` David Miller [this message]
2017-01-25 1:08 ` [lkp-robot] [ipv6] 31cdaa587d: BUG:sleeping_function_called_from_invalid_context_at_kernel/locking/mutex.c kernel test robot
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