From: Oleg Nesterov <oleg@tv-sign.ru>
To: Rusty Russell <rusty@rustcorp.com.au>
Cc: linux-kernel@vger.kernel.org, travis@sgi.com,
Ingo Molnar <mingo@elte.hu>, Gautham R Shenoy <ego@in.ibm.com>
Subject: Re: [PATCH 6/7] work_on_cpu: use on x86/kernel/cpu/intel_cacheinfo.c
Date: Thu, 23 Oct 2008 11:46:21 +0200 [thread overview]
Message-ID: <20081023094621.GA7995@redhat.com> (raw)
In-Reply-To: <20081023005750.D0A11DDEF9@ozlabs.org>
On 10/23, Rusty Russell wrote:
>
> +static int __cpuinit detect_cache_attributes(unsigned int cpu)
> +{
> + int retval;
> +
> + if (num_cache_leaves == 0)
> + return -ENOENT;
> +
> + per_cpu(cpuid4_info, cpu) = kzalloc(
> + sizeof(struct _cpuid4_info) * num_cache_leaves, GFP_KERNEL);
> + if (per_cpu(cpuid4_info, cpu) == NULL)
> + return -ENOMEM;
> +
> + retval = work_on_cpu(cpu, get_cpu_leaves, NULL);
This doesn't look right.
cache_add_dev()->cpuid4_cache_sysfs_init()->detect_cache_attributes()
is called by CPU_ONLINE under cpu_hotplug_begin(), this is deadlockable.
Yes, the caller (cpu_hotplug.active_writer) can safely take
get_online_cpus(), but if we have another pending work which needs
get_online_cpus(), we have the deadlock.
Oleg.
next prev parent reply other threads:[~2008-10-23 9:46 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-10-23 16:55 [PATCH 6/7] work_on_cpu: use on x86/kernel/cpu/intel_cacheinfo.c Rusty Russell
2008-10-23 9:46 ` Oleg Nesterov [this message]
2008-10-23 15:10 ` Rusty Russell
2008-10-23 16:16 ` Oleg Nesterov
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