* Ingo Molnar <mingo@xxxxxxx> [2009-02-12 12:28:54]: > > * KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx> wrote: > > > On Thu, 12 Feb 2009 11:21:13 +0100 > > Ingo Molnar <mingo@xxxxxxx> wrote: > > > > > > > > * Ingo Molnar <mingo@xxxxxxx> 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@xxxxxxx> > > > 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? We needed the local IRQ flags, since these counters are updated from page fault context and from reclaim context with lru_lock held with IRQ's disabled. I've been thinking about replacing the spin lock with seq lock, but have not gotten to it yet. -- Balbir -- To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
