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From: Michael Ellerman <michael@ellerman.id.au>
To: "Srivatsa S. Bhat" <srivatsa.bhat@linux.vnet.ibm.com>
Cc: peterz@infradead.org, fweisbec@gmail.com,
	linux-kernel@vger.kernel.org, Paul Mackerras <paulus@samba.org>,
	walken@google.com, mingo@kernel.org, linux-arch@vger.kernel.org,
	vincent.guittot@linaro.org, xiaoguangrong@linux.vnet.ibm.com,
	wangyun@linux.vnet.ibm.com, paulmck@linux.vnet.ibm.com,
	nikunj@linux.vnet.ibm.com, linux-pm@vger.kernel.org,
	rusty@rustcorp.com.au, rostedt@goodmis.org,
	Ian Munsie <imunsie@au1.ibm.com>,
	namhyung@kernel.org, tglx@linutronix.de, laijs@cn.fujitsu.com,
	zhong@linux.vnet.ibm.com, netdev@vger.kernel.org,
	oleg@redhat.com, sbw@mit.edu, tj@kernel.org,
	akpm@linux-foundation.org, linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH 40/45] powerpc, irq: Use GFP_ATOMIC allocations in atomic context
Date: Tue, 25 Jun 2013 12:08:42 +1000	[thread overview]
Message-ID: <20130625020842.GD14051@concordia> (raw)
In-Reply-To: <20130623134657.19094.93687.stgit@srivatsabhat.in.ibm.com>

On Sun, Jun 23, 2013 at 07:17:00PM +0530, Srivatsa S. Bhat wrote:
> The function migrate_irqs() is called with interrupts disabled
> and hence its not safe to do GFP_KERNEL allocations inside it,
> because they can sleep. So change the gfp mask to GFP_ATOMIC.

OK so it gets there via:
  __stop_machine()
    take_cpu_down()
      __cpu_disable()
        smp_ops->cpu_disable()
          generic_cpu_disable()
            migrate_irqs()

> diff --git a/arch/powerpc/kernel/irq.c b/arch/powerpc/kernel/irq.c
> index ea185e0..ca39bac 100644
> --- a/arch/powerpc/kernel/irq.c
> +++ b/arch/powerpc/kernel/irq.c
> @@ -412,7 +412,7 @@ void migrate_irqs(void)
>  	cpumask_var_t mask;
>  	const struct cpumask *map = cpu_online_mask;
>  
> -	alloc_cpumask_var(&mask, GFP_KERNEL);
> +	alloc_cpumask_var(&mask, GFP_ATOMIC);

We're not checking for allocation failure, which we should be.

But this code is only used on powermac and 85xx, so it should probably
just be a TODO to fix this up to handle the failure.

cheers

  reply	other threads:[~2013-06-25  2:08 UTC|newest]

Thread overview: 67+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-06-23 13:37 [PATCH 00/45] CPU hotplug: stop_machine()-free CPU hotplug, part 1 Srivatsa S. Bhat
2013-06-23 13:38 ` [PATCH 01/45] CPU hotplug: Provide APIs to prevent CPU offline from atomic context Srivatsa S. Bhat
2013-06-24 22:49   ` Steven Rostedt
2013-06-23 13:38 ` [PATCH 02/45] CPU hotplug: Clarify the usage of different synchronization APIs Srivatsa S. Bhat
2013-06-23 13:38 ` [PATCH 03/45] Documentation, CPU hotplug: Recommend usage of get/put_online_cpus_atomic() Srivatsa S. Bhat
2013-06-23 13:38 ` [PATCH 04/45] CPU hotplug: Add infrastructure to check lacking hotplug synchronization Srivatsa S. Bhat
2013-06-24 23:26   ` Steven Rostedt
2013-06-25 18:49     ` Srivatsa S. Bhat
2013-06-23 13:39 ` [PATCH 05/45] CPU hotplug: Protect set_cpu_online() to avoid false-positives Srivatsa S. Bhat
2013-06-23 13:39 ` [PATCH 06/45] CPU hotplug: Sprinkle debugging checks to catch locking bugs Srivatsa S. Bhat
2013-06-23 13:39 ` [PATCH 07/45] CPU hotplug: Expose the new debug config option Srivatsa S. Bhat
2013-06-23 15:08   ` Sergei Shtylyov
2013-06-23 18:58     ` Srivatsa S. Bhat
2013-06-23 13:39 ` [PATCH 08/45] CPU hotplug: Convert preprocessor macros to static inline functions Srivatsa S. Bhat
2013-06-23 13:40 ` [PATCH 09/45] smp: Use get/put_online_cpus_atomic() to prevent CPU offline Srivatsa S. Bhat
2013-06-23 13:40 ` [PATCH 10/45] sched/core: " Srivatsa S. Bhat
2013-06-23 13:40 ` [PATCH 11/45] migration: Use raw_spin_lock/unlock since interrupts are already disabled Srivatsa S. Bhat
2013-06-23 13:40 ` [PATCH 12/45] sched/fair: Use get/put_online_cpus_atomic() to prevent CPU offline Srivatsa S. Bhat
2013-06-23 13:40 ` [PATCH 13/45] timer: " Srivatsa S. Bhat
2013-06-23 13:41 ` [PATCH 14/45] sched/rt: " Srivatsa S. Bhat
2013-06-23 13:41 ` [PATCH 15/45] rcu: " Srivatsa S. Bhat
2013-06-23 13:41 ` [PATCH 16/45] tick-broadcast: " Srivatsa S. Bhat
2013-06-23 13:41 ` [PATCH 17/45] time/clocksource: " Srivatsa S. Bhat
2013-06-23 13:42 ` [PATCH 18/45] softirq: " Srivatsa S. Bhat
2013-06-23 13:42 ` [PATCH 19/45] irq: " Srivatsa S. Bhat
2013-06-23 13:42 ` [PATCH 20/45] net: " Srivatsa S. Bhat
2013-06-23 13:42 ` [PATCH 21/45] block: " Srivatsa S. Bhat
2013-06-23 13:42 ` [PATCH 22/45] percpu_counter: " Srivatsa S. Bhat
2013-06-24 17:55   ` Tejun Heo
2013-06-24 18:06     ` Tejun Heo
2013-06-24 18:09       ` Srivatsa S. Bhat
2013-06-23 13:43 ` [PATCH 23/45] infiniband: ehca: " Srivatsa S. Bhat
2013-06-23 13:43 ` [PATCH 24/45] [SCSI] fcoe: " Srivatsa S. Bhat
2013-06-23 13:43 ` [PATCH 25/45] staging/octeon: " Srivatsa S. Bhat
2013-06-23 18:17   ` Greg Kroah-Hartman
2013-06-23 18:55     ` Srivatsa S. Bhat
2013-06-23 19:17       ` Joe Perches
2013-06-24 17:25         ` Srivatsa S. Bhat
2013-06-24 18:17       ` David Daney
2013-06-23 13:43 ` [PATCH 26/45] x86: " Srivatsa S. Bhat
2013-06-23 13:43 ` [PATCH 27/45] perf/x86: " Srivatsa S. Bhat
2013-06-23 13:44 ` [PATCH 28/45] KVM: " Srivatsa S. Bhat
2013-06-23 13:44 ` [PATCH 29/45] kvm/vmx: " Srivatsa S. Bhat
2013-06-23 13:44 ` [PATCH 30/45] x86/xen: " Srivatsa S. Bhat
2013-06-23 13:45 ` [PATCH 31/45] alpha/smp: " Srivatsa S. Bhat
2013-06-23 17:50   ` Matt Turner
2013-06-23 18:56     ` Srivatsa S. Bhat
2013-06-23 13:45 ` [PATCH 32/45] blackfin/smp: " Srivatsa S. Bhat
2013-06-23 13:45 ` [PATCH 33/45] cris/smp: " Srivatsa S. Bhat
2013-06-24  6:41   ` Jesper Nilsson
2013-06-23 13:45 ` [PATCH 34/45] hexagon/smp: " Srivatsa S. Bhat
2013-06-23 13:45 ` [PATCH 35/45] ia64: irq, perfmon: " Srivatsa S. Bhat
2013-06-23 13:46 ` [PATCH 36/45] ia64: smp, tlb: " Srivatsa S. Bhat
2013-06-23 13:46 ` [PATCH 37/45] m32r: " Srivatsa S. Bhat
2013-06-23 13:46 ` [PATCH 38/45] MIPS: " Srivatsa S. Bhat
2013-06-23 13:46 ` [PATCH 39/45] mn10300: " Srivatsa S. Bhat
2013-06-23 13:47 ` [PATCH 40/45] powerpc, irq: Use GFP_ATOMIC allocations in atomic context Srivatsa S. Bhat
2013-06-25  2:08   ` Michael Ellerman [this message]
2013-06-25  2:13     ` Benjamin Herrenschmidt
2013-06-25  2:58       ` Michael Ellerman
2013-06-25  3:13         ` Benjamin Herrenschmidt
2013-06-25 19:20           ` Srivatsa S. Bhat
2013-06-23 13:47 ` [PATCH 41/45] powerpc: Use get/put_online_cpus_atomic() to prevent CPU offline Srivatsa S. Bhat
2013-06-23 13:47 ` [PATCH 42/45] powerpc: Use get/put_online_cpus_atomic() to avoid false-positive warning Srivatsa S. Bhat
2013-06-23 13:47 ` [PATCH 43/45] sh: Use get/put_online_cpus_atomic() to prevent CPU offline Srivatsa S. Bhat
2013-06-23 13:48 ` [PATCH 44/45] sparc: " Srivatsa S. Bhat
2013-06-23 13:48 ` [PATCH 45/45] tile: " Srivatsa S. Bhat

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