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Date: Mon, 12 Nov 2007 11:15:26 -0800
From: "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
To: Benjamin Herrenschmidt <benh@...nel.crashing.org>
Cc: Steven Rostedt <rostedt@...dmis.org>, linux-kernel@...r.kernel.org,
tony@...eyournoodle.com, paulus@...ba.org, dino@...ibm.com,
tytso@...ibm.com, dvhltc@...ibm.com, niv@...ibm.com,
antonb@...ibm.com
Subject: Re: [PATCH, RFC] improved hacks to allow -rt to run kernbench on POWER
On Mon, Nov 12, 2007 at 07:48:45AM +1100, Benjamin Herrenschmidt wrote:
>
> On Sun, 2007-11-11 at 09:45 -0500, Steven Rostedt wrote:
> > > Well, I suppose the patch could go in, maybe with some ifdef's
> > around
> > > the bits in _switch_to, there's little point in doing that on non-rt
> > > kernels.
> >
> > As Nick Piggin already stated, and I'll even state it for the RT
> > kernel,
> > we do not allow preemption in switch_to. So it is safe to remove those
> > "preempt_disable" bits from the patch
>
> Sure, I know that, I'm not talking about that, I'm talking about the
> added code that flush pending batches & save the batch state, since on
> non-rt kernel, this is not useful (the batch is only ever active within
> a spinlocked section, which cannot be preempted on non-rt).
And here is an updated patch. There has to be a better way than the
#ifdef, but I need the two local variables, and breaking the intervening
code out into a separate function didn't quite seem right either.
Thoughts?
This one does only one oops during boot-up, which I will start looking
at:
BUG: sleeping function called from invalid context ifconfig(994) at kernel/rtmutex.c:637
in_atomic():1 [00000002], irqs_disabled():1
Call Trace:
[c0000000ff49f030] [c000000000010028] .show_stack+0x6c/0x1a0 (unreliable)
[c0000000ff49f0d0] [c00000000004f8b4] .__might_sleep+0x11c/0x138
[c0000000ff49f150] [c00000000039c920] .__rt_spin_lock+0x38/0xa0
[c0000000ff49f1d0] [c0000000000cf8e8] .kmem_cache_alloc+0x68/0x184
[c0000000ff49f270] [c0000000001f7534] .radix_tree_node_alloc+0x3c/0x104
[c0000000ff49f300] [c0000000001f8418] .radix_tree_insert+0x19c/0x324
[c0000000ff49f3c0] [c00000000000b758] .irq_radix_revmap+0x140/0x178
[c0000000ff49f470] [c000000000044aec] .xics_startup+0x30/0x54
[c0000000ff49f500] [c0000000000997f4] .setup_irq+0x254/0x320
[c0000000ff49f5b0] [c000000000099984] .request_irq+0xc4/0x114
[c0000000ff49f660] [d00000000079b194] .e1000_open+0xdc/0x1b8 [e1000]
[c0000000ff49f6f0] [c00000000030a840] .dev_open+0x94/0x110
[c0000000ff49f790] [c00000000030a69c] .dev_change_flags+0x110/0x220
[c0000000ff49f830] [c00000000036a0a8] .devinet_ioctl+0x2cc/0x764
[c0000000ff49f930] [c00000000036a6a8] .inet_ioctl+0xe8/0x138
[c0000000ff49f9b0] [c0000000002f9acc] .sock_ioctl+0x2c8/0x314
[c0000000ff49fa50] [c0000000000e6dec] .do_ioctl+0x5c/0xf0
[c0000000ff49faf0] [c0000000000e731c] .vfs_ioctl+0x49c/0x4d4
[c0000000ff49fba0] [c0000000000e73ec] .sys_ioctl+0x98/0xe0
[c0000000ff49fc50] [c000000000117944] .dev_ifsioc+0x1e0/0x46c
[c0000000ff49fd40] [c00000000011e1d4] .compat_sys_ioctl+0x40c/0x4a0
[c0000000ff49fe30] [c00000000000852c] syscall_exit+0x0/0x40
Signed-off-by: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
---
arch/powerpc/kernel/process.c | 22 ++++++++++++++++++++++
arch/powerpc/kernel/prom.c | 2 +-
arch/powerpc/mm/tlb_64.c | 5 ++++-
arch/powerpc/platforms/pseries/eeh.c | 2 +-
drivers/of/base.c | 2 +-
include/asm-powerpc/tlb.h | 5 ++++-
include/asm-powerpc/tlbflush.h | 15 ++++++++++-----
7 files changed, 43 insertions(+), 10 deletions(-)
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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