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Groups > linux.kernel > #1537756

[tip:smp/hotplug] tracing/rb: Init the CPU mask on allocation

From tip-bot for Sebastian Andrzej Siewior <tipbot@zytor.com>
Newsgroups linux.kernel
Subject [tip:smp/hotplug] tracing/rb: Init the CPU mask on allocation
Date 2016-12-07 14:50 +0100
Message-ID <sLKLD-Il-1@gated-at.bofh.it> (permalink)
References <sLKBY-Fd-19@gated-at.bofh.it>
Organization linux.* mail to news gateway

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Commit-ID:  b18cc3de00ec3442cf40ac60787dbe0703b99e24
Gitweb:     http://git.kernel.org/tip/b18cc3de00ec3442cf40ac60787dbe0703b99e24
Author:     Sebastian Andrzej Siewior <bigeasy@linutronix.de>
AuthorDate: Wed, 7 Dec 2016 14:31:33 +0100
Committer:  Thomas Gleixner <tglx@linutronix.de>
CommitDate: Wed, 7 Dec 2016 14:36:21 +0100

tracing/rb: Init the CPU mask on allocation

Before commit b32614c03413 ("tracing/rb: Convert to hotplug state machine")
the allocated cpumask was initialized to the mask of online or possible
CPUs. After the CPU hotplug changes the buffer initialization moved to
trace_rb_cpu_prepare() but the cpumask is allocated with alloc_cpumask()
and therefor has random content. As a consequence the cpu buffers are not
initialized and a later access dereferences a NULL pointer.

Use zalloc_cpumask() instead so trace_rb_cpu_prepare() initializes the
buffers properly.

Fixes: b32614c03413 ("tracing/rb: Convert to hotplug state machine")
Reported-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: rostedt@goodmis.org
Link: http://lkml.kernel.org/r/20161207133133.hzkcqfllxcdi3joz@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

---
 kernel/trace/ring_buffer.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index a7a055f..89a2611a16 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -1297,7 +1297,7 @@ struct ring_buffer *__ring_buffer_alloc(unsigned long size, unsigned flags,
 	if (!buffer)
 		return NULL;
 
-	if (!alloc_cpumask_var(&buffer->cpumask, GFP_KERNEL))
+	if (!zalloc_cpumask_var(&buffer->cpumask, GFP_KERNEL))
 		goto fail_free_buffer;
 
 	nr_pages = DIV_ROUND_UP(size, BUF_PAGE_SIZE);

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Thread

cpu hotplug: convert more drivers (batch #6 and last) Sebastian Andrzej Siewior <bigeasy@linutronix.de> - 2016-11-27 00:20 +0100
  [PATCH 01/22] cpufreq/acpi-cpufreq: Convert to hotplug state machine Sebastian Andrzej Siewior <bigeasy@linutronix.de> - 2016-11-27 00:20 +0100
    Re: [PATCH 01/22] cpufreq/acpi-cpufreq: Convert to hotplug state  machine Viresh Kumar <viresh.kumar@linaro.org> - 2016-11-28 06:20 +0100
      Re: [PATCH 01/22] cpufreq/acpi-cpufreq: Convert to hotplug state  machine Sebastian Andrzej Siewior <bigeasy@linutronix.de> - 2016-11-28 10:50 +0100
        [PATCH 01/22 v2] cpufreq/acpi-cpufreq: Convert to hotplug state  machine Sebastian Andrzej Siewior <bigeasy@linutronix.de> - 2016-11-28 11:00 +0100
          Re: [PATCH 01/22 v2] cpufreq/acpi-cpufreq: Convert to hotplug state  machine Viresh Kumar <viresh.kumar@linaro.org> - 2016-11-28 11:00 +0100
          Re: [PATCH 01/22 v2] cpufreq/acpi-cpufreq: Convert to hotplug state machine "Rafael J. Wysocki" <rafael@kernel.org> - 2016-11-28 13:50 +0100
  [PATCH 13/22] iommu/vt-d: Convert to hotplug state machine Sebastian Andrzej Siewior <bigeasy@linutronix.de> - 2016-11-27 00:20 +0100
    [tip:smp/hotplug] iommu/vt-d: Convert to hotplug state machine tip-bot for Anna-Maria Gleixner <tipbot@zytor.com> - 2016-12-02 01:20 +0100
  [PATCH 11/22] mm/zswap: Convert dst-mem to hotplug state machine Sebastian Andrzej Siewior <bigeasy@linutronix.de> - 2016-11-27 00:20 +0100
    [tip:smp/hotplug] mm/zswap: Convert dst-mem to hotplug state  machine tip-bot for Sebastian Andrzej Siewior <tipbot@zytor.com> - 2016-12-02 01:20 +0100
  [PATCH 19/22] soc/fsl/qbman: Convert to hotplug state machine Sebastian Andrzej Siewior <bigeasy@linutronix.de> - 2016-11-27 00:20 +0100
    [tip:smp/hotplug] soc/fsl/qbman: Convert to hotplug state machine tip-bot for Sebastian Andrzej Siewior <tipbot@zytor.com> - 2016-12-02 01:20 +0100
  [PATCH 04/22] idle/intel: Convert to hotplug state machine Sebastian Andrzej Siewior <bigeasy@linutronix.de> - 2016-11-27 00:20 +0100
    Re: [PATCH 04/22] idle/intel: Convert to hotplug state machine Thomas Gleixner <tglx@linutronix.de> - 2016-11-28 18:40 +0100
      Re: [PATCH 04/22] idle/intel: Convert to hotplug state machine Sebastian Andrzej Siewior <bigeasy@linutronix.de> - 2016-11-29 10:50 +0100
        [PATCH 04/22 v2] idle/intel: Convert to hotplug state machine Sebastian Andrzej Siewior <bigeasy@linutronix.de> - 2016-11-29 11:00 +0100
  [PATCH 07/22] mm/vmstat: Drop get_online_cpus() from init_cpu_node_state/vmstat_cpu_dead() Sebastian Andrzej Siewior <bigeasy@linutronix.de> - 2016-11-27 00:20 +0100
    Re: [PATCH 07/22] mm/vmstat: Drop get_online_cpus() from  init_cpu_node_state/vmstat_cpu_dead() Michal Hocko <mhocko@kernel.org> - 2016-11-28 10:30 +0100
    [tip:smp/hotplug] mm/vmstat: Drop get_online_cpus() from  init_cpu_node_state/vmstat_cpu_dead() tip-bot for Sebastian Andrzej Siewior <tipbot@zytor.com> - 2016-12-02 01:20 +0100
  [PATCH 03/22] idle/intel: Remove superfluous SMP fuction call Sebastian Andrzej Siewior <bigeasy@linutronix.de> - 2016-11-27 00:20 +0100
  [PATCH 06/22] tracing/rb: Convert to hotplug state machine Sebastian Andrzej Siewior <bigeasy@linutronix.de> - 2016-11-27 00:20 +0100
    [tip:smp/hotplug] tracing/rb: Convert to hotplug state machine tip-bot for Sebastian Andrzej Siewior <tipbot@zytor.com> - 2016-12-02 01:20 +0100
      [linux-next] tracing/rb: NULL pointer dereference at  trace_rb_cpu_prepare() Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> - 2016-12-07 12:20 +0100
        [PATCH] tracing/rb: init the CPU mask on allocation Sebastian Andrzej Siewior <bigeasy@linutronix.de> - 2016-12-07 14:40 +0100
          [tip:smp/hotplug] tracing/rb: Init the CPU mask on allocation tip-bot for Sebastian Andrzej Siewior <tipbot@zytor.com> - 2016-12-07 14:50 +0100
          Re: [PATCH] tracing/rb: init the CPU mask on allocation Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> - 2016-12-07 15:40 +0100
  [PATCH 16/22] arm64/cpuinfo: Convert to hotplug state machine Sebastian Andrzej Siewior <bigeasy@linutronix.de> - 2016-11-27 00:20 +0100
    Re: [PATCH 16/22] arm64/cpuinfo: Convert to hotplug state machine Suzuki K Poulose <suzuki.poulose@arm.com> - 2016-11-29 18:30 +0100
    [tip:smp/hotplug] arm64/cpuinfo: Convert to hotplug state machine tip-bot for Anna-Maria Gleixner <tipbot@zytor.com> - 2016-12-02 01:20 +0100
  [PATCH 22/22] Remove obsolete cpu hotplug register / unregister functions Sebastian Andrzej Siewior <bigeasy@linutronix.de> - 2016-11-27 00:20 +0100
  [PATCH 18/22] zram: Convert to hotplug state machine Sebastian Andrzej Siewior <bigeasy@linutronix.de> - 2016-11-27 00:20 +0100
    [tip:smp/hotplug] zram: Convert to hotplug state machine tip-bot for Anna-Maria Gleixner <tipbot@zytor.com> - 2016-12-02 01:20 +0100

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