From: Christoph Lameter <cl@linux.com>
To: Tejun Heo <tj@kernel.org>
Cc: akpm@linuxfoundation.org, rostedt@goodmis.org,
linux-kernel@vger.kernel.org, Ingo Molnar <mingo@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Thomas Gleixner <tglx@linutronix.de>,
Rusty Russell <rusty@rustcorp.com.au>
Subject: [PATCH 4/6] Use raw_cpu_write for initialization of per cpu refcount.
Date: Tue, 15 Oct 2013 12:47:26 -0500 [thread overview]
Message-ID: <20131015174746.793436648@linux.com> (raw)
In-Reply-To: 20131015174722.615394057@linux.com
[-- Attachment #1: preempt_module --]
[-- Type: text/plain, Size: 1967 bytes --]
The initialization of a structure is not subject to synchronization.
The use of __this_cpu would trigger a false positive with the
additional preemption checks for __this_cpu ops.
So simply disable the check through the use of raw_cpu ops.
Trace:
[ 0.668066] __this_cpu_write operation in preemptible [00000000] code: modprobe/286
[ 0.668108] caller is __this_cpu_preempt_check+0x38/0x60
[ 0.668111] CPU: 3 PID: 286 Comm: modprobe Tainted: GF 3.12.0-rc4+ #187
[ 0.668112] Hardware name: FUJITSU CELSIUS W530 Power/D3227-A1, BIOS V4.6.5.4 R1.10.0 for D3227-A1x 09/16/2013
[ 0.668113] 0000000000000003 ffff8807edda1d18 ffffffff816d5a57 ffff8807edda1fd8
[ 0.668117] ffff8807edda1d48 ffffffff8137359c ffff8807edda1ef8 ffffffffa0002178
[ 0.668121] ffffc90000067730 ffff8807edda1e48 ffff8807edda1d88 ffffffff813735f8
[ 0.668124] Call Trace:
[ 0.668129] [<ffffffff816d5a57>] dump_stack+0x4e/0x82
[ 0.668132] [<ffffffff8137359c>] check_preemption_disabled+0xec/0x110
[ 0.668135] [<ffffffff813735f8>] __this_cpu_preempt_check+0x38/0x60
[ 0.668139] [<ffffffff810c24fd>] load_module+0xcfd/0x2650
[ 0.668143] [<ffffffff816dd922>] ? page_fault+0x22/0x30
[ 0.668146] [<ffffffff810c3ef6>] SyS_init_module+0xa6/0xd0
[ 0.668150] [<ffffffff816e4fd3>] tracesys+0xe1/0xe6
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Christoph Lameter <cl@linux.com>
Index: linux/kernel/module.c
===================================================================
--- linux.orig/kernel/module.c 2013-09-05 13:43:30.557687773 -0500
+++ linux/kernel/module.c 2013-10-07 12:33:43.732059759 -0500
@@ -643,7 +643,7 @@ static int module_unload_init(struct mod
INIT_LIST_HEAD(&mod->target_list);
/* Hold reference count during initialization. */
- __this_cpu_write(mod->refptr->incs, 1);
+ raw_cpu_write(mod->refptr->incs, 1);
/* Backwards compatibility macros put refcount during init. */
mod->waiter = current;
next prev parent reply other threads:[~2013-10-15 17:55 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-10-15 17:47 [PATCH 0/6] percpu: Implement Preemption checks for __this_cpu operations V4b Christoph Lameter
2013-10-15 17:47 ` [PATCH 1/6] net: ip4_datagram_connect: Use correct form of statistics update Christoph Lameter
2013-10-15 18:36 ` Eric Dumazet
2013-10-16 6:09 ` Ingo Molnar
2013-10-16 8:35 ` Peter Zijlstra
2013-10-16 9:14 ` Eric Dumazet
2013-10-16 9:26 ` Ingo Molnar
2013-10-16 14:27 ` Christoph Lameter
2013-10-16 14:37 ` Eric Dumazet
2013-10-15 17:47 ` [PATCH 2/6] percpu: Add raw_cpu_ops Christoph Lameter
2013-10-15 17:47 ` [PATCH 3/6] mm: Use raw_cpu ops for determining current NUMA node Christoph Lameter
2013-10-16 8:38 ` Peter Zijlstra
2013-10-16 14:22 ` Christoph Lameter
2013-10-15 17:47 ` Christoph Lameter [this message]
2013-10-16 8:43 ` [PATCH 4/6] Use raw_cpu_write for initialization of per cpu refcount Peter Zijlstra
2013-10-15 17:47 ` [PATCH 5/6] net: __this_cpu_inc in route.c Christoph Lameter
2013-10-16 8:46 ` Peter Zijlstra
2013-10-16 9:22 ` Eric Dumazet
2013-10-16 10:25 ` Peter Zijlstra
2013-10-16 15:07 ` Christoph Lameter
2013-10-15 17:47 ` [PATCH 6/6] percpu: Add preemption checks to __this_cpu ops Christoph Lameter
2013-10-16 8:49 ` Peter Zijlstra
2013-10-16 15:09 ` Christoph Lameter
2013-10-16 15:36 ` Peter Zijlstra
2013-10-16 15:55 ` Christoph Lameter
2013-10-16 16:25 ` Peter Zijlstra
2013-10-16 16:52 ` Steven Rostedt
2013-10-16 17:11 ` Peter Zijlstra
2013-10-16 17:39 ` Steven Rostedt
2013-10-16 18:38 ` Peter Zijlstra
2013-10-17 19:22 ` Christoph Lameter
2013-10-17 21:13 ` Peter Zijlstra
[not found] <20131011175518.634285474@linux.com>
2013-10-11 17:55 ` [PATCH 4/6] Use raw_cpu_write for initialization of per cpu refcount Christoph Lameter
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