Subject: [merged] modules-use-raw_cpu_write-for-initialization-of-per-cpu-refcount.patch removed from -mm tree
To: cl@xxxxxxxxx,mingo@xxxxxxxxxx,rusty@xxxxxxxxxxxxxxx,tj@xxxxxxxxxx,mm-commits@xxxxxxxxxxxxxxx
From: akpm@xxxxxxxxxxxxxxxxxxxx
Date: Tue, 08 Apr 2014 14:46:41 -0700
The patch titled
Subject: modules: use raw_cpu_write for initialization of per cpu refcount.
has been removed from the -mm tree. Its filename was
modules-use-raw_cpu_write-for-initialization-of-per-cpu-refcount.patch
This patch was dropped because it was merged into mainline or a subsystem tree
------------------------------------------------------
From: Christoph Lameter <cl@xxxxxxxxx>
Subject: modules: use raw_cpu_write for initialization of per cpu refcount.
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
Signed-off-by: Christoph Lameter <cl@xxxxxxxxx>
Acked-by: Ingo Molnar <mingo@xxxxxxxxxx>
Acked-by: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
Cc: Tejun Heo <tj@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/module.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff -puN kernel/module.c~modules-use-raw_cpu_write-for-initialization-of-per-cpu-refcount kernel/module.c
--- a/kernel/module.c~modules-use-raw_cpu_write-for-initialization-of-per-cpu-refcount
+++ a/kernel/module.c
@@ -640,7 +640,7 @@ 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);
return 0;
}
_
Patches currently in -mm which might be from cl@xxxxxxxxx are
origin.patch
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