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Message-ID: <20071213061029.GB25047@linux.vnet.ibm.com>
Date: Wed, 12 Dec 2007 22:10:29 -0800
From: "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
To: Steven Rostedt <rostedt@...dmis.org>
Cc: linux-kernel@...r.kernel.org, tony@...eyournoodle.com,
paulus@...ba.org, benh@...nel.crashing.org, dino@...ibm.com,
tytso@...ibm.com, dvhltc@...ibm.com, antonb@...ibm.com
Subject: Re: [PATCH, RFC] hacks to allow -rt to run kernbench on POWER
On Wed, Dec 12, 2007 at 10:56:12PM -0500, Steven Rostedt wrote:
>
> On Mon, 29 Oct 2007, Paul E. McKenney wrote:
> > diff -urpNa -X dontdiff linux-2.6.23.1-rt4/mm/memory.c linux-2.6.23.1-rt4-fix/mm/memory.c
> > --- linux-2.6.23.1-rt4/mm/memory.c 2007-10-27 22:20:57.000000000 -0700
> > +++ linux-2.6.23.1-rt4-fix/mm/memory.c 2007-10-28 15:40:36.000000000 -0700
> > @@ -664,6 +664,7 @@ static unsigned long zap_pte_range(struc
> > int anon_rss = 0;
> >
> > pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
> > + preempt_disable();
> > arch_enter_lazy_mmu_mode();
> > do {
> > pte_t ptent = *pte;
> > @@ -732,6 +733,7 @@ static unsigned long zap_pte_range(struc
> >
> > add_mm_rss(mm, file_rss, anon_rss);
> > arch_leave_lazy_mmu_mode();
> > + preempt_enable();
> > pte_unmap_unlock(pte - 1, ptl);
> >
> > return addr;
>
> I'm pulling your patch for the above added code. Took me a few hours to
> find the culprit, but I was getting scheduling in atomic bugs. Turns out
> that this code you put "preempt_disable" in calls sleeping spinlocks.
>
> Might want to run with DEBUG_PREEMPT.
I thought that you had already pulled the above version...
Here is the replacement that I posted on November 9th (with much help
from Ben H):
http://lkml.org/lkml/2007/11/9/114
Thanx, Paul
Signed-off-by: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
---
diff -urpNa -X dontdiff linux-2.6.23.1-rt4/arch/powerpc/kernel/process.c linux-2.6.23.1-rt4-fix/arch/powerpc/kernel/process.c
--- linux-2.6.23.1-rt4/arch/powerpc/kernel/process.c 2007-10-12 09:43:44.000000000 -0700
+++ linux-2.6.23.1-rt4-fix/arch/powerpc/kernel/process.c 2007-11-12 09:18:55.000000000 -0800
@@ -245,6 +245,10 @@ struct task_struct *__switch_to(struct t
struct thread_struct *new_thread, *old_thread;
unsigned long flags;
struct task_struct *last;
+#ifdef CONFIG_PREEMPT_RT
+ struct ppc64_tlb_batch *batch;
+ int hadbatch;
+#endif /* #ifdef CONFIG_PREEMPT_RT */
#ifdef CONFIG_SMP
/* avoid complexity of lazy save/restore of fpu
@@ -325,6 +329,17 @@ struct task_struct *__switch_to(struct t
}
#endif
+#ifdef CONFIG_PREEMPT_RT
+ batch = &__get_cpu_var(ppc64_tlb_batch);
+ if (batch->active) {
+ hadbatch = 1;
+ if (batch->index) {
+ __flush_tlb_pending(batch);
+ }
+ batch->active = 0;
+ }
+#endif /* #ifdef CONFIG_PREEMPT_RT */
+
local_irq_save(flags);
account_system_vtime(current);
@@ -335,6 +350,13 @@ struct task_struct *__switch_to(struct t
local_irq_restore(flags);
+#ifdef CONFIG_PREEMPT_RT
+ if (hadbatch) {
+ batch = &__get_cpu_var(ppc64_tlb_batch);
+ batch->active = 1;
+ }
+#endif /* #ifdef CONFIG_PREEMPT_RT */
+
return last;
}
diff -urpNa -X dontdiff linux-2.6.23.1-rt4/arch/powerpc/kernel/prom.c linux-2.6.23.1-rt4-fix/arch/powerpc/kernel/prom.c
--- linux-2.6.23.1-rt4/arch/powerpc/kernel/prom.c 2007-10-12 09:43:44.000000000 -0700
+++ linux-2.6.23.1-rt4-fix/arch/powerpc/kernel/prom.c 2007-10-28 13:37:23.000000000 -0700
@@ -80,7 +80,7 @@ struct boot_param_header *initial_boot_p
extern struct device_node *allnodes; /* temporary while merging */
-extern rwlock_t devtree_lock; /* temporary while merging */
+extern raw_rwlock_t devtree_lock; /* temporary while merging */
/* export that to outside world */
struct device_node *of_chosen;
diff -urpNa -X dontdiff linux-2.6.23.1-rt4/arch/powerpc/mm/tlb_64.c linux-2.6.23.1-rt4-fix/arch/powerpc/mm/tlb_64.c
--- linux-2.6.23.1-rt4/arch/powerpc/mm/tlb_64.c 2007-10-27 22:20:57.000000000 -0700
+++ linux-2.6.23.1-rt4-fix/arch/powerpc/mm/tlb_64.c 2007-11-08 16:49:04.000000000 -0800
@@ -133,7 +133,7 @@ void pgtable_free_tlb(struct mmu_gather
void hpte_need_flush(struct mm_struct *mm, unsigned long addr,
pte_t *ptep, unsigned long pte, int huge)
{
- struct ppc64_tlb_batch *batch = &__get_cpu_var(ppc64_tlb_batch);
+ struct ppc64_tlb_batch *batch = &get_cpu_var(ppc64_tlb_batch);
unsigned long vsid, vaddr;
unsigned int psize;
real_pte_t rpte;
@@ -180,6 +180,7 @@ void hpte_need_flush(struct mm_struct *m
*/
if (!batch->active) {
flush_hash_page(vaddr, rpte, psize, 0);
+ put_cpu_var(ppc64_tlb_batch);
return;
}
@@ -212,12 +213,14 @@ void hpte_need_flush(struct mm_struct *m
*/
if (machine_is(celleb)) {
__flush_tlb_pending(batch);
+ put_cpu_var(ppc64_tlb_batch);
return;
}
#endif /* CONFIG_PREEMPT_RT */
if (i >= PPC64_TLB_BATCH_NR)
__flush_tlb_pending(batch);
+ put_cpu_var(ppc64_tlb_batch);
}
/*
diff -urpNa -X dontdiff linux-2.6.23.1-rt4/arch/powerpc/platforms/pseries/eeh.c linux-2.6.23.1-rt4-fix/arch/powerpc/platforms/pseries/eeh.c
--- linux-2.6.23.1-rt4/arch/powerpc/platforms/pseries/eeh.c 2007-10-12 09:43:44.000000000 -0700
+++ linux-2.6.23.1-rt4-fix/arch/powerpc/platforms/pseries/eeh.c 2007-10-28 15:43:54.000000000 -0700
@@ -97,7 +97,7 @@ int eeh_subsystem_enabled;
EXPORT_SYMBOL(eeh_subsystem_enabled);
/* Lock to avoid races due to multiple reports of an error */
-static DEFINE_SPINLOCK(confirm_error_lock);
+static DEFINE_RAW_SPINLOCK(confirm_error_lock);
/* Buffer for reporting slot-error-detail rtas calls. Its here
* in BSS, and not dynamically alloced, so that it ends up in
diff -urpNa -X dontdiff linux-2.6.23.1-rt4/drivers/of/base.c linux-2.6.23.1-rt4-fix/drivers/of/base.c
--- linux-2.6.23.1-rt4/drivers/of/base.c 2007-10-12 09:43:44.000000000 -0700
+++ linux-2.6.23.1-rt4-fix/drivers/of/base.c 2007-10-28 13:38:36.000000000 -0700
@@ -25,7 +25,7 @@ struct device_node *allnodes;
/* use when traversing tree through the allnext, child, sibling,
* or parent members of struct device_node.
*/
-DEFINE_RWLOCK(devtree_lock);
+DEFINE_RAW_RWLOCK(devtree_lock);
int of_n_addr_cells(struct device_node *np)
{
diff -urpNa -X dontdiff linux-2.6.23.1-rt4/include/asm-powerpc/tlbflush.h linux-2.6.23.1-rt4-fix/include/asm-powerpc/tlbflush.h
--- linux-2.6.23.1-rt4/include/asm-powerpc/tlbflush.h 2007-10-12 09:43:44.000000000 -0700
+++ linux-2.6.23.1-rt4-fix/include/asm-powerpc/tlbflush.h 2007-11-08 17:11:18.000000000 -0800
@@ -109,18 +109,23 @@ extern void hpte_need_flush(struct mm_st
static inline void arch_enter_lazy_mmu_mode(void)
{
- struct ppc64_tlb_batch *batch = &__get_cpu_var(ppc64_tlb_batch);
+ struct ppc64_tlb_batch *batch = &get_cpu_var(ppc64_tlb_batch);
batch->active = 1;
+ put_cpu_var(ppc64_tlb_batch);
}
static inline void arch_leave_lazy_mmu_mode(void)
{
- struct ppc64_tlb_batch *batch = &__get_cpu_var(ppc64_tlb_batch);
+ struct ppc64_tlb_batch *batch = &get_cpu_var(ppc64_tlb_batch);
- if (batch->index)
- __flush_tlb_pending(batch);
- batch->active = 0;
+ if (batch->active) {
+ if (batch->index) {
+ __flush_tlb_pending(batch);
+ }
+ batch->active = 0;
+ }
+ put_cpu_var(ppc64_tlb_batch);
}
#define arch_flush_lazy_mmu_mode() do {} while (0)
diff -urpNa -X dontdiff linux-2.6.23.1-rt4/include/asm-powerpc/tlb.h linux-2.6.23.1-rt4-fix/include/asm-powerpc/tlb.h
--- linux-2.6.23.1-rt4/include/asm-powerpc/tlb.h 2007-10-12 09:43:44.000000000 -0700
+++ linux-2.6.23.1-rt4-fix/include/asm-powerpc/tlb.h 2007-10-28 11:36:05.000000000 -0700
@@ -44,8 +44,11 @@ static inline void tlb_flush(struct mmu_
* pages are going to be freed and we really don't want to have a CPU
* access a freed page because it has a stale TLB
*/
- if (tlbbatch->index)
+ if (tlbbatch->index) {
+ preempt_disable();
__flush_tlb_pending(tlbbatch);
+ preempt_enable();
+ }
pte_free_finish();
}
--
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