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Message-Id: <20090212194644.98d275cf.kamezawa.hiroyu@jp.fujitsu.com>
Date: Thu, 12 Feb 2009 19:46:44 +0900
From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
To: Ingo Molnar <mingo@...e.hu>
Cc: Frederic Weisbecker <fweisbec@...il.com>,
Peter Zijlstra <a.p.zijlstra@...llo.nl>,
Thomas Gleixner <tglx@...x.de>,
LKML <linux-kernel@...r.kernel.org>,
rt-users <linux-rt-users@...r.kernel.org>,
Steven Rostedt <rostedt@...dmis.org>,
Peter Zijlstra <peterz@...radead.org>,
Carsten Emde <ce@...g.ch>,
Clark Williams <williams@...hat.com>,
"balbir@...ux.vnet.ibm.com" <balbir@...ux.vnet.ibm.com>
Subject: Re: [patch] rt: res_counter fix, v2
On Thu, 12 Feb 2009 11:21:13 +0100
Ingo Molnar <mingo@...e.hu> wrote:
>
> * Ingo Molnar <mingo@...e.hu> wrote:
>
> > Frederic, could you try the patch below?
>
> Please try v2 below - it might even build ;-)
>
> Ingo
>
> ------------------->
> Subject: rt: res_counter fix
> From: Ingo Molnar <mingo@...e.hu>
> Date: Thu Feb 12 11:11:47 CET 2009
>
> Frederic Weisbecker reported this warning:
>
> [ 45.228562] BUG: sleeping function called from invalid context at kernel/rtmutex.c:683
> [ 45.228571] in_atomic(): 0, irqs_disabled(): 1, pid: 4290, name: ntpdate
> [ 45.228576] INFO: lockdep is turned off.
> [ 45.228580] irq event stamp: 0
> [ 45.228583] hardirqs last enabled at (0): [<(null)>] (null)
> [ 45.228589] hardirqs last disabled at (0): [<ffffffff8025449d>] copy_process+0x68d/0x1500
> [ 45.228602] softirqs last enabled at (0): [<ffffffff8025449d>] copy_process+0x68d/0x1500
> [ 45.228609] softirqs last disabled at (0): [<(null)>] (null)
> [ 45.228617] Pid: 4290, comm: ntpdate Tainted: G W 2.6.29-rc4-rt1-tip #1
> [ 45.228622] Call Trace:
> [ 45.228632] [<ffffffff8027dfb0>] ? print_irqtrace_events+0xd0/0xe0
> [ 45.228639] [<ffffffff8024cd73>] __might_sleep+0x113/0x130
> [ 45.228646] [<ffffffff8077c811>] rt_spin_lock+0xa1/0xb0
> [ 45.228653] [<ffffffff80296a3d>] res_counter_charge+0x5d/0x130
> [ 45.228660] [<ffffffff802fb67f>] __mem_cgroup_try_charge+0x7f/0x180
> [ 45.228667] [<ffffffff802fc407>] mem_cgroup_charge_common+0x57/0x90
> [ 45.228674] [<ffffffff80212096>] ? ftrace_call+0x5/0x2b
> [ 45.228680] [<ffffffff802fc49d>] mem_cgroup_newpage_charge+0x5d/0x60
> [ 45.228688] [<ffffffff802d94ce>] __do_fault+0x29e/0x4c0
> [ 45.228694] [<ffffffff8077c843>] ? rt_spin_unlock+0x23/0x80
> [ 45.228700] [<ffffffff802db8b5>] handle_mm_fault+0x205/0x890
> [ 45.228707] [<ffffffff80212096>] ? ftrace_call+0x5/0x2b
> [ 45.228714] [<ffffffff8023495e>] do_page_fault+0x11e/0x2a0
> [ 45.228720] [<ffffffff8077e5a5>] page_fault+0x25/0x30
> [ 45.228727] [<ffffffff8043e1ed>] ? __clear_user+0x3d/0x70
> [ 45.228733] [<ffffffff8043e1d1>] ? __clear_user+0x21/0x70
>
> The reason is the raw IRQ flag use of kernel/res_counter.c.
>
> The irq flags tricks there seem a bit pointless: it cannot
> protect the c->parent linkage because local_irq_save() is
> only per CPU.
>
> So replace it with _nort(). This code needs a second look.
>
I'm sorry for no knowledge about RT. Could you teach me what
local_irq_save_nort() does ?
Hmm, how about just replacaing _irq() with preempt_disable()/enable() ?
xxx_nort() is better ?
AFAIK, these will not be called from irq context. (Added Balbir to CC:)
Regards,
-Kame
> Reported-by: Frederic Weisbecker <fweisbec@...il.com>
> Signed-off-by: Ingo Molnar <mingo@...e.hu>
> ---
> kernel/res_counter.c | 9 +++++----
> 1 file changed, 5 insertions(+), 4 deletions(-)
>
> Index: tip/kernel/res_counter.c
> ===================================================================
> --- tip.orig/kernel/res_counter.c
> +++ tip/kernel/res_counter.c
> @@ -14,6 +14,7 @@
> #include <linux/res_counter.h>
> #include <linux/uaccess.h>
> #include <linux/mm.h>
> +#include <linux/interrupt.h>
>
> void res_counter_init(struct res_counter *counter, struct res_counter *parent)
> {
> @@ -43,7 +44,7 @@ int res_counter_charge(struct res_counte
> struct res_counter *c, *u;
>
> *limit_fail_at = NULL;
> - local_irq_save(flags);
> + local_irq_save_nort(flags);
> for (c = counter; c != NULL; c = c->parent) {
> spin_lock(&c->lock);
> ret = res_counter_charge_locked(c, val);
> @@ -62,7 +63,7 @@ undo:
> spin_unlock(&u->lock);
> }
> done:
> - local_irq_restore(flags);
> + local_irq_restore_nort(flags);
> return ret;
> }
>
> @@ -79,13 +80,13 @@ void res_counter_uncharge(struct res_cou
> unsigned long flags;
> struct res_counter *c;
>
> - local_irq_save(flags);
> + local_irq_save_nort(flags);
> for (c = counter; c != NULL; c = c->parent) {
> spin_lock(&c->lock);
> res_counter_uncharge_locked(c, val);
> spin_unlock(&c->lock);
> }
> - local_irq_restore(flags);
> + local_irq_restore_nort(flags);
> }
>
>
> --
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