lkml.org 
[lkml]   [2009]   [Feb]   [12]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [patch] rt: res_counter fix, v2

    * KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> wrote:

    > On Thu, 12 Feb 2009 11:21:13 +0100
    > Ingo Molnar <mingo@elte.hu> wrote:
    >
    > >
    > > * Ingo Molnar <mingo@elte.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@elte.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:)

    _nort() will just turn them into NOPs in essence.

    The question is, are these local IRQ flags manipulations really needed
    in this code, and if yes, why?

    Ingo


    \
     
     \ /
      Last update: 2009-02-12 12:31    [W:0.041 / U:8.060 seconds]
    ©2003-2017 Jasper Spaans. hosted at Digital OceanAdvertise on this site