linux-kernel - Re: tip: origin tree boot crash

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Date:	Mon, 1 Mar 2010 15:55:19 +0100
From:	Steffen Klassert <steffen.klassert@...unet.com>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	Herbert Xu <herbert@...dor.apana.org.au>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	"David S. Miller" <davem@...emloft.net>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Linux Crypto Mailing List <linux-crypto@...r.kernel.org>
Subject: Re: tip: origin tree boot crash

Hi.

On Mon, Mar 01, 2010 at 08:50:24AM +0100, Ingo Molnar wrote:
> 
> Hi,
> 
> * Herbert Xu <herbert@...dor.apana.org.au> wrote:
> 
> >       crypto: pcrypt - Add pcrypt crypto parallelization wrapper
> 
> -tip testing started triggering the following frequent boot crash yesterday, 
> on 64-bit x86:
> 
>  |  calling  pcrypt_init+0x0/0xee @ 1
>  |  BUG: unable to handle kernel NULL pointer dereference at (null)
>  |  IP: [<ffffffff8126550b>] memcpy+0xb/0xb0
>  |  Call Trace:
>  |   [<ffffffff810c2f38>] ? padata_alloc+0x98/0x150
>  |   [<ffffffff82158c51>] ? pcrypt_init+0x0/0xee
>  |   [<ffffffff82158ccc>] pcrypt_init+0x7b/0xee
> 

Ugh, it seems that I forgot to allocate one of the cpumasks. Looking at the
configs of my test systems I noticed, that CONFIG_CPUMASK_OFFSTACK was
not set on all the configs, so I did not notice it.

The patch below fixes the boot crash if CONFIG_CPUMASK_OFFSTACK is
enabled on my test systems. Does the patch fix it for you too?

Thanks,

Steffen

Subject: [PATCH] padata: allocate the cpumask for the padata instance

The cpumask of the padata instance was used without allocated.
This caused boot crashes if CONFIG_CPUMASK_OFFSTACK is enabled.
This patch fixes this by doing proper allocation for this cpumask.

Signed-off-by: Steffen Klassert <steffen.klassert@...unet.com>
---
 kernel/padata.c |    8 +++++++-
 1 files changed, 7 insertions(+), 1 deletions(-)

diff --git a/kernel/padata.c b/kernel/padata.c
index 6f9bcb8..93caf65 100644
--- a/kernel/padata.c
+++ b/kernel/padata.c
@@ -642,6 +642,9 @@ struct padata_instance *padata_alloc(const struct cpumask *cpumask,
 	if (!pd)
 		goto err_free_inst;
 
+	if (!alloc_cpumask_var(&pinst->cpumask, GFP_KERNEL))
+		goto err_free_pd;
+
 	rcu_assign_pointer(pinst->pd, pd);
 
 	pinst->wq = wq;
@@ -654,12 +657,14 @@ struct padata_instance *padata_alloc(const struct cpumask *cpumask,
 	pinst->cpu_notifier.priority = 0;
 	err = register_hotcpu_notifier(&pinst->cpu_notifier);
 	if (err)
-		goto err_free_pd;
+		goto err_free_cpumask;
 
 	mutex_init(&pinst->lock);
 
 	return pinst;
 
+err_free_cpumask:
+	free_cpumask_var(pinst->cpumask);
 err_free_pd:
 	padata_free_pd(pd);
 err_free_inst:
@@ -685,6 +690,7 @@ void padata_free(struct padata_instance *pinst)
 
 	unregister_hotcpu_notifier(&pinst->cpu_notifier);
 	padata_free_pd(pinst->pd);
+	free_cpumask_var(pinst->cpumask);
 	kfree(pinst);
 }
 EXPORT_SYMBOL(padata_free);
-- 
1.5.6.5

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