[PATCH 0/1] x86: fix remove cpu_pda table patch

[PATCH 0/1] x86: fix remove cpu_pda table patch

[Mike Travis]

[Ingo - please replace "PATCH 07/11" with this one.]

    *	Remove 544k bytes from the kernel by removing the boot_cpu_pda
	array from the data section and allocating it during startup.

	Fixed panic in setup_per_cpu_areas when HOTPLUG_CPU not set.

For inclusion into sched-devel/latest tree.

Based on:
git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6.git
+   sched-devel/latest  .../mingo/linux-2.6-sched-devel.git


Signed-off-by: Mike Travis <travis@sgi.com>
---

-- 

[PATCH 1/1] x86: remove static boot_cpu_pda array v2

[Mike Travis]

[-- Attachment #1: rm-boot_pdas --]
[-- Type: text/plain, Size: 9833 bytes --]

  * Remove the boot_cpu_pda array and pointer table from the data section.
    Allocate the pointer table and array during init.  do_boot_cpu()
    will reallocate the pda in node local memory and if the cpu is being
    brought up before the bootmem array is released (after_bootmem = 0),
    then it will free the initial pda.  This will happen for all cpus
    present at system startup.

    This removes 512k + 32k bytes from the data section.


For inclusion into sched-devel/latest tree.

Based on:
	git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6.git
    +   sched-devel/latest  .../mingo/linux-2.6-sched-devel.git


Signed-off-by: Mike Travis <travis@sgi.com>
---
v2: Fixed panic in setup_per_cpu_areas when HOTPLUG_CPU not set.
---
 arch/x86/kernel/head64.c  |   26 ++++++++++++++--
 arch/x86/kernel/setup.c   |   73 +++++++++++++++++++++++++++++++++++-----------
 arch/x86/kernel/setup64.c |    8 +++--
 arch/x86/kernel/smpboot.c |   59 ++++++++++++++++++++++++++++---------
 include/asm-x86/pda.h     |    6 +--
 include/linux/mm.h        |    1 
 6 files changed, 135 insertions(+), 38 deletions(-)

--- linux-2.6.sched.orig/arch/x86/kernel/head64.c
+++ linux-2.6.sched/arch/x86/kernel/head64.c
@@ -25,6 +25,24 @@
 #include <asm/e820.h>
 #include <asm/bios_ebda.h>
 
+/* boot cpu pda */
+static struct x8664_pda _boot_cpu_pda __read_mostly;
+
+#ifdef CONFIG_SMP
+#ifdef CONFIG_DEBUG_PER_CPU_MAPS
+/*
+ * We install an empty cpu_pda pointer table to trap references before
+ * the actual cpu_pda pointer table is created in setup_cpu_pda_map().
+ */
+static struct x8664_pda *__cpu_pda[NR_CPUS] __initdata;
+#else
+static struct x8664_pda *__cpu_pda[1] __read_mostly;
+#endif
+
+#else /* !CONFIG_SMP (NR_CPUS will be 1) */
+static struct x8664_pda *__cpu_pda[NR_CPUS] __read_mostly;
+#endif
+
 static void __init zap_identity_mappings(void)
 {
 	pgd_t *pgd = pgd_offset_k(0UL);
@@ -156,10 +174,12 @@ void __init x86_64_start_kernel(char * r
 
 	early_printk("Kernel alive\n");
 
- 	for (i = 0; i < NR_CPUS; i++)
- 		cpu_pda(i) = &boot_cpu_pda[i];
-
+	_cpu_pda = __cpu_pda;
+	cpu_pda(0) = &_boot_cpu_pda;
 	pda_init(0);
+
+	early_printk("Kernel really alive\n");
+
 	copy_bootdata(__va(real_mode_data));
 
 	reserve_early(__pa_symbol(&_text), __pa_symbol(&_end), "TEXT DATA BSS");
--- linux-2.6.sched.orig/arch/x86/kernel/setup.c
+++ linux-2.6.sched/arch/x86/kernel/setup.c
@@ -100,6 +100,50 @@ static inline void setup_cpumask_of_cpu(
  */
 unsigned long __per_cpu_offset[NR_CPUS] __read_mostly;
 EXPORT_SYMBOL(__per_cpu_offset);
+static inline void setup_cpu_pda_map(void) { }
+
+#elif !defined(CONFIG_SMP)
+static inline void setup_cpu_pda_map(void) { }
+
+#else /* CONFIG_SMP && CONFIG_X86_64 */
+
+/*
+ * Allocate cpu_pda pointer table and array via alloc_bootmem.
+ */
+static void __init setup_cpu_pda_map(void)
+{
+	char *pda;
+	struct x8664_pda **new_cpu_pda;
+	unsigned long size;
+	int cpu;
+
+	size = roundup(sizeof(struct x8664_pda), cache_line_size());
+
+	/* allocate cpu_pda array and pointer table */
+	{
+		unsigned long tsize = nr_cpu_ids * sizeof(void *);
+		unsigned long asize = size * (nr_cpu_ids - 1);
+
+		tsize = roundup(tsize, cache_line_size());
+		new_cpu_pda = alloc_bootmem(tsize + asize);
+		pda = (char *)new_cpu_pda + tsize;
+	}
+
+	/* initialize pointer table to static pda's */
+	for_each_possible_cpu(cpu) {
+		if (cpu == 0) {
+			/* leave boot cpu pda in place */
+			new_cpu_pda[0] = cpu_pda(0);
+			continue;
+		}
+		new_cpu_pda[cpu] = (struct x8664_pda *)pda;
+		new_cpu_pda[cpu]->in_bootmem = 1;
+		pda += size;
+	}
+
+	/* point to new pointer table */
+	_cpu_pda = new_cpu_pda;
+}
 #endif
 
 /*
@@ -109,46 +153,43 @@ EXPORT_SYMBOL(__per_cpu_offset);
  */
 void __init setup_per_cpu_areas(void)
 {
-	int i, highest_cpu = 0;
-	unsigned long size;
+	ssize_t size = PERCPU_ENOUGH_ROOM;
+	char *ptr;
+	int cpu;
 
 #ifdef CONFIG_HOTPLUG_CPU
 	prefill_possible_map();
+#else
+	nr_cpu_ids = num_processors;
 #endif
 
+	/* Setup cpu_pda map */
+	setup_cpu_pda_map();
+
 	/* Copy section for each CPU (we discard the original) */
 	size = PERCPU_ENOUGH_ROOM;
 	printk(KERN_INFO "PERCPU: Allocating %lu bytes of per cpu data\n",
 			  size);
 
-	for_each_possible_cpu(i) {
-		char *ptr;
+	for_each_possible_cpu(cpu) {
 #ifndef CONFIG_NEED_MULTIPLE_NODES
 		ptr = alloc_bootmem_pages(size);
 #else
-		int node = early_cpu_to_node(i);
+		int node = early_cpu_to_node(cpu);
 		if (!node_online(node) || !NODE_DATA(node)) {
 			ptr = alloc_bootmem_pages(size);
 			printk(KERN_INFO
 			       "cpu %d has no node %d or node-local memory\n",
-				i, node);
+				cpu, node);
 		}
 		else
 			ptr = alloc_bootmem_pages_node(NODE_DATA(node), size);
 #endif
-		if (!ptr)
-			panic("Cannot allocate cpu data for CPU %d\n", i);
-#ifdef CONFIG_X86_64
-		cpu_pda(i)->data_offset = ptr - __per_cpu_start;
-#else
-		__per_cpu_offset[i] = ptr - __per_cpu_start;
-#endif
+		per_cpu_offset(cpu) = ptr - __per_cpu_start;
 		memcpy(ptr, __per_cpu_start, __per_cpu_end - __per_cpu_start);
 
-		highest_cpu = i;
 	}
 
-	nr_cpu_ids = highest_cpu + 1;
 	printk(KERN_DEBUG "NR_CPUS: %d, nr_cpu_ids: %d, nr_node_ids %d\n",
 		NR_CPUS, nr_cpu_ids, nr_node_ids);
 
@@ -198,7 +239,7 @@ void __cpuinit numa_set_node(int cpu, in
 {
 	int *cpu_to_node_map = early_per_cpu_ptr(x86_cpu_to_node_map);
 
-	if (node != NUMA_NO_NODE)
+	if (cpu_pda(cpu) && node != NUMA_NO_NODE)
 		cpu_pda(cpu)->nodenumber = node;
 
 	if (cpu_to_node_map)
--- linux-2.6.sched.orig/arch/x86/kernel/setup64.c
+++ linux-2.6.sched/arch/x86/kernel/setup64.c
@@ -12,6 +12,7 @@
 #include <linux/bitops.h>
 #include <linux/module.h>
 #include <linux/kgdb.h>
+#include <linux/topology.h>
 #include <asm/pda.h>
 #include <asm/pgtable.h>
 #include <asm/processor.h>
@@ -34,9 +35,8 @@ struct boot_params boot_params;
 
 cpumask_t cpu_initialized __cpuinitdata = CPU_MASK_NONE;
 
-struct x8664_pda *_cpu_pda[NR_CPUS] __read_mostly;
+struct x8664_pda **_cpu_pda __read_mostly;
 EXPORT_SYMBOL(_cpu_pda);
-struct x8664_pda boot_cpu_pda[NR_CPUS] __cacheline_aligned;
 
 struct desc_ptr idt_descr = { 256 * 16 - 1, (unsigned long) idt_table };
 
@@ -114,8 +114,10 @@ void pda_init(int cpu)
 			__get_free_pages(GFP_ATOMIC, IRQSTACK_ORDER);
 		if (!pda->irqstackptr)
 			panic("cannot allocate irqstack for cpu %d", cpu); 
-	}
 
+		if (pda->nodenumber == 0 && cpu_to_node(cpu) != NUMA_NO_NODE)
+			pda->nodenumber = cpu_to_node(cpu);
+	}
 
 	pda->irqstackptr += IRQSTACKSIZE-64;
 } 
--- linux-2.6.sched.orig/arch/x86/kernel/smpboot.c
+++ linux-2.6.sched/arch/x86/kernel/smpboot.c
@@ -809,6 +809,43 @@ static void __cpuinit do_fork_idle(struc
 	complete(&c_idle->done);
 }
 
+/*
+ * Allocate node local memory for the AP pda.
+ *
+ * Must be called after the _cpu_pda pointer table is initialized.
+ */
+static int __cpuinit get_local_pda(int cpu)
+{
+	struct x8664_pda *oldpda, *newpda;
+	unsigned long size = sizeof(struct x8664_pda);
+	int node = cpu_to_node(cpu);
+
+	if (cpu_pda(cpu) && !cpu_pda(cpu)->in_bootmem)
+		return 0;
+
+	oldpda = cpu_pda(cpu);
+	newpda = kmalloc_node(size, GFP_ATOMIC, node);
+	if (!newpda) {
+		printk(KERN_ERR "Could not allocate node local PDA "
+			"for CPU %d on node %d\n", cpu, node);
+
+		if (oldpda)
+			return 0;	/* have a usable pda */
+		else
+			return -1;
+	}
+
+	if (oldpda) {
+		memcpy(newpda, oldpda, size);
+		if (!after_bootmem)
+			free_bootmem((unsigned long)oldpda, size);
+	}
+
+	newpda->in_bootmem = 0;
+	cpu_pda(cpu) = newpda;
+	return 0;
+}
+
 static int __cpuinit do_boot_cpu(int apicid, int cpu)
 /*
  * NOTE - on most systems this is a PHYSICAL apic ID, but on multiquad
@@ -834,19 +871,11 @@ static int __cpuinit do_boot_cpu(int api
 	}
 
 	/* Allocate node local memory for AP pdas */
-	if (cpu_pda(cpu) == &boot_cpu_pda[cpu]) {
-		struct x8664_pda *newpda, *pda;
-		int node = cpu_to_node(cpu);
-		pda = cpu_pda(cpu);
-		newpda = kmalloc_node(sizeof(struct x8664_pda), GFP_ATOMIC,
-				      node);
-		if (newpda) {
-			memcpy(newpda, pda, sizeof(struct x8664_pda));
-			cpu_pda(cpu) = newpda;
-		} else
-			printk(KERN_ERR
-		"Could not allocate node local PDA for CPU %d on node %d\n",
-				cpu, node);
+	if (cpu > 0) {
+		boot_error = get_local_pda(cpu);
+		if (boot_error)
+			goto restore_state;
+			/* if can't get pda memory, can't start cpu */
 	}
 #endif
 
@@ -965,6 +994,8 @@ do_rest:
 		}
 	}
 
+restore_state:
+
 	if (boot_error) {
 		/* Try to put things back the way they were before ... */
 		unmap_cpu_to_logical_apicid(cpu);
@@ -1338,6 +1369,8 @@ __init void prefill_possible_map(void)
 
 	for (i = 0; i < possible; i++)
 		cpu_set(i, cpu_possible_map);
+
+	nr_cpu_ids = possible;
 }
 
 static void __ref remove_cpu_from_maps(int cpu)
--- linux-2.6.sched.orig/include/asm-x86/pda.h
+++ linux-2.6.sched/include/asm-x86/pda.h
@@ -20,7 +20,8 @@ struct x8664_pda {
 					/* gcc-ABI: this canary MUST be at
 					   offset 40!!! */
 	char *irqstackptr;
-	int nodenumber;			/* number of current node */
+	short nodenumber;		/* number of current node (32k max) */
+	short in_bootmem;		/* pda lives in bootmem */
 	unsigned int __softirq_pending;
 	unsigned int __nmi_count;	/* number of NMI on this CPUs */
 	short mmu_state;
@@ -36,8 +37,7 @@ struct x8664_pda {
 	unsigned irq_spurious_count;
 } ____cacheline_aligned_in_smp;
 
-extern struct x8664_pda *_cpu_pda[];
-extern struct x8664_pda boot_cpu_pda[];
+extern struct x8664_pda **_cpu_pda;
 extern void pda_init(int);
 
 #define cpu_pda(i) (_cpu_pda[i])
--- linux-2.6.sched.orig/include/linux/mm.h
+++ linux-2.6.sched/include/linux/mm.h
@@ -1002,6 +1002,7 @@ extern void mem_init(void);
 extern void show_mem(void);
 extern void si_meminfo(struct sysinfo * val);
 extern void si_meminfo_node(struct sysinfo *val, int nid);
+extern int after_bootmem;
 
 #ifdef CONFIG_NUMA
 extern void setup_per_cpu_pageset(void);

-- 

Re: [PATCH 0/1] x86: fix remove cpu_pda table patch

[Ingo Molnar]

* Mike Travis <travis@sgi.com> wrote:

> [Ingo - please replace "PATCH 07/11" with this one.]
> 
>     *	Remove 544k bytes from the kernel by removing the boot_cpu_pda
> 	array from the data section and allocating it during startup.
> 
> 	Fixed panic in setup_per_cpu_areas when HOTPLUG_CPU not set.
> 
> For inclusion into sched-devel/latest tree.

sched-devel.git randconfig testing found another crash with your queue:

[    0.111060] Brought up 1 CPUs
[    0.111986] Total of 1 processors activated (4022.73 BogoMIPS).
[    0.112987] Testing NMI watchdog ... <1>BUG: unable to handle kernel NULL pointer dereference at 0000000000000040
[    0.114982] IP: [<ffffffff8180d4a0>] check_nmi_watchdog+0xb0/0x210
[    0.114982] PGD 0
[    0.114982] Oops: 0000 [1] SMP
[    0.114982] CPU 0
[............]

 http://redhat.com/~mingo/misc/config-Mon_Apr_28_23_25_25_CEST_2008.bad
 http://redhat.com/~mingo/misc/log-Mon_Apr_28_23_25_25_CEST_2008.bad

	Ingo

Re: [PATCH 0/1] x86: fix remove cpu_pda table patch

[Mike Travis]

Ingo Molnar wrote:
> * Mike Travis <travis@sgi.com> wrote:
> 
>> [Ingo - please replace "PATCH 07/11" with this one.]
>>
>>     *	Remove 544k bytes from the kernel by removing the boot_cpu_pda
>> 	array from the data section and allocating it during startup.
>>
>> 	Fixed panic in setup_per_cpu_areas when HOTPLUG_CPU not set.
>>
>> For inclusion into sched-devel/latest tree.
> 
> sched-devel.git randconfig testing found another crash with your queue:
> 
> [    0.111060] Brought up 1 CPUs
> [    0.111986] Total of 1 processors activated (4022.73 BogoMIPS).
> [    0.112987] Testing NMI watchdog ... <1>BUG: unable to handle kernel NULL pointer dereference at 0000000000000040
> [    0.114982] IP: [<ffffffff8180d4a0>] check_nmi_watchdog+0xb0/0x210
> [    0.114982] PGD 0
> [    0.114982] Oops: 0000 [1] SMP
> [    0.114982] CPU 0
> [............]
> 
>  http://redhat.com/~mingo/misc/config-Mon_Apr_28_23_25_25_CEST_2008.bad
>  http://redhat.com/~mingo/misc/log-Mon_Apr_28_23_25_25_CEST_2008.bad
> 
> 	Ingo

Ouch! ;-) Ok, I'll check it out.

Thanks,
Mike

Re: [PATCH 0/1] x86: fix remove cpu_pda table patch

[Mike Travis]

Ingo Molnar wrote:
> * Mike Travis <travis@sgi.com> wrote:
> 
>> [Ingo - please replace "PATCH 07/11" with this one.]
>>
>>     *	Remove 544k bytes from the kernel by removing the boot_cpu_pda
>> 	array from the data section and allocating it during startup.
>>
>> 	Fixed panic in setup_per_cpu_areas when HOTPLUG_CPU not set.
>>
>> For inclusion into sched-devel/latest tree.
> 
> sched-devel.git randconfig testing found another crash with your queue:
> 
> [    0.111060] Brought up 1 CPUs
> [    0.111986] Total of 1 processors activated (4022.73 BogoMIPS).
> [    0.112987] Testing NMI watchdog ... <1>BUG: unable to handle kernel NULL pointer dereference at 0000000000000040
> [    0.114982] IP: [<ffffffff8180d4a0>] check_nmi_watchdog+0xb0/0x210
> [    0.114982] PGD 0
> [    0.114982] Oops: 0000 [1] SMP
> [    0.114982] CPU 0
> [............]
> 
>  http://redhat.com/~mingo/misc/config-Mon_Apr_28_23_25_25_CEST_2008.bad
>  http://redhat.com/~mingo/misc/log-Mon_Apr_28_23_25_25_CEST_2008.bad
> 
> 	Ingo

Hi Ingo,

I need a bit more information on your hardware configuration.  Building a
kernel with the above config file started up fine on both the Intel and AMD
boxes.

Based on the above output it looks like it might be a UP machine?  

Thanks,
Mike 

Re: [PATCH 0/1] x86: fix remove cpu_pda table patch

[Mike Travis]

Mike Travis wrote:
> Ingo Molnar wrote:
>> * Mike Travis <travis@sgi.com> wrote:
>>
>>> [Ingo - please replace "PATCH 07/11" with this one.]
>>>
>>>     *	Remove 544k bytes from the kernel by removing the boot_cpu_pda
>>> 	array from the data section and allocating it during startup.
>>>
>>> 	Fixed panic in setup_per_cpu_areas when HOTPLUG_CPU not set.
>>>
>>> For inclusion into sched-devel/latest tree.
>> sched-devel.git randconfig testing found another crash with your queue:
>>
>> [    0.111060] Brought up 1 CPUs
>> [    0.111986] Total of 1 processors activated (4022.73 BogoMIPS).
>> [    0.112987] Testing NMI watchdog ... <1>BUG: unable to handle kernel NULL pointer dereference at 0000000000000040
>> [    0.114982] IP: [<ffffffff8180d4a0>] check_nmi_watchdog+0xb0/0x210
>> [    0.114982] PGD 0
>> [    0.114982] Oops: 0000 [1] SMP
>> [    0.114982] CPU 0
>> [............]
>>
>>  http://redhat.com/~mingo/misc/config-Mon_Apr_28_23_25_25_CEST_2008.bad
>>  http://redhat.com/~mingo/misc/log-Mon_Apr_28_23_25_25_CEST_2008.bad
>>
>> 	Ingo
> 
> Hi Ingo,
> 
> I need a bit more information on your hardware configuration.  Building a
> kernel with the above config file started up fine on both the Intel and AMD
> boxes.
> 
> Based on the above output it looks like it might be a UP machine?  
...

Ok, I think I found it.  In check_nmi_watchdog():


        for (cpu = 0; cpu < NR_CPUS; cpu++)
                prev_nmi_count[cpu] = cpu_pda(cpu)->__nmi_count;

As I mentioned it works fine on both of my systems so could you try it out?

Thanks!
Mike
--
Subject: [PATCH 1/1] x86: change check_nmi_watchdog to use nr_cpu_ids

  * Change function check_nmi_watchdog() to use nr_cpu_ids instead of NR_CPUS.

Based on:
	git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6.git
    +   sched-devel/latest  .../mingo/linux-2.6-sched-devel.git


Signed-off-by: Mike Travis <travis@sgi.com>
---
 arch/x86/kernel/nmi_64.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- linux-2.6.sched.orig/arch/x86/kernel/nmi_64.c
+++ linux-2.6.sched/arch/x86/kernel/nmi_64.c
@@ -88,7 +88,7 @@ int __init check_nmi_watchdog(void)
 	if (!atomic_read(&nmi_active))
 		return 0;
 
-	prev_nmi_count = kmalloc(NR_CPUS * sizeof(int), GFP_KERNEL);
+	prev_nmi_count = kmalloc(nr_cpu_ids * sizeof(int), GFP_KERNEL);
 	if (!prev_nmi_count)
 		return -1;
 
@@ -99,7 +99,7 @@ int __init check_nmi_watchdog(void)
 		smp_call_function(nmi_cpu_busy, (void *)&endflag, 0, 0);
 #endif
 
-	for (cpu = 0; cpu < NR_CPUS; cpu++)
+	for (cpu = 0; cpu < nr_cpu_ids; cpu++)
 		prev_nmi_count[cpu] = cpu_pda(cpu)->__nmi_count;
 	local_irq_enable();
 	mdelay((20*1000)/nmi_hz); // wait 20 ticks

Re: [PATCH 0/1] x86: fix remove cpu_pda table patch

[Ingo Molnar]

* Mike Travis <travis@sgi.com> wrote:

> -	prev_nmi_count = kmalloc(NR_CPUS * sizeof(int), GFP_KERNEL);
> +	prev_nmi_count = kmalloc(nr_cpu_ids * sizeof(int), GFP_KERNEL);

yeah, that makes sense ... i'll reinstate your patches and check.

	Ingo

Re: [PATCH 0/1] x86: fix remove cpu_pda table patch

[Ingo Molnar]

* Ingo Molnar <mingo@elte.hu> wrote:

> * Mike Travis <travis@sgi.com> wrote:
> 
> > -	prev_nmi_count = kmalloc(NR_CPUS * sizeof(int), GFP_KERNEL);
> > +	prev_nmi_count = kmalloc(nr_cpu_ids * sizeof(int), GFP_KERNEL);
> 
> yeah, that makes sense ... i'll reinstate your patches and check.

they crashed after about 3 randconfig iterations with:

  early res: 4 [8000-afff] PGTABLE
  early res: 5 [b000-b87f] MEMNODEMAP
PANIC: early exception 0e rip 10:ffffffff8077a150 error 2 cr2 37
Pid: 0, comm: swapper Not tainted 2.6.25-sched-devel.git-x86-latest.git #14

Call Trace:
 [<ffffffff81466196>] early_idt_handler+0x56/0x6a
 [<ffffffff8077a150>] ? numa_set_node+0x30/0x60
 [<ffffffff8077a129>] ? numa_set_node+0x9/0x60
 [<ffffffff8147a543>] numa_init_array+0x93/0xf0
 [<ffffffff8147b039>] acpi_scan_nodes+0x3b9/0x3f0
 [<ffffffff8147a496>] numa_initmem_init+0x136/0x150
 [<ffffffff8146da5f>] setup_arch+0x48f/0x700
 [<ffffffff802566ea>] ? clockevents_register_notifier+0x3a/0x50
 [<ffffffff81466a87>] start_kernel+0xd7/0x440
 [<ffffffff81466422>] x86_64_start_kernel+0x222/0x280

RIP 0x10


 http://redhat.com/~mingo/misc/log-Wed_Apr_30_00_28_09_CEST_2008.bad
 http://redhat.com/~mingo/misc/config-Wed_Apr_30_00_28_09_CEST_2008.bad

	Ingo

Re: [PATCH 0/1] x86: fix remove cpu_pda table patch

[Mike Travis]

Ingo Molnar wrote:
> * Ingo Molnar <mingo@elte.hu> wrote:
> 
>> * Mike Travis <travis@sgi.com> wrote:
>>
>>> -	prev_nmi_count = kmalloc(NR_CPUS * sizeof(int), GFP_KERNEL);
>>> +	prev_nmi_count = kmalloc(nr_cpu_ids * sizeof(int), GFP_KERNEL);
>> yeah, that makes sense ... i'll reinstate your patches and check.
> 
> they crashed after about 3 randconfig iterations with:
> 
>   early res: 4 [8000-afff] PGTABLE
>   early res: 5 [b000-b87f] MEMNODEMAP
> PANIC: early exception 0e rip 10:ffffffff8077a150 error 2 cr2 37
> Pid: 0, comm: swapper Not tainted 2.6.25-sched-devel.git-x86-latest.git #14
> 
> Call Trace:
>  [<ffffffff81466196>] early_idt_handler+0x56/0x6a
>  [<ffffffff8077a150>] ? numa_set_node+0x30/0x60
>  [<ffffffff8077a129>] ? numa_set_node+0x9/0x60
>  [<ffffffff8147a543>] numa_init_array+0x93/0xf0
>  [<ffffffff8147b039>] acpi_scan_nodes+0x3b9/0x3f0
>  [<ffffffff8147a496>] numa_initmem_init+0x136/0x150
>  [<ffffffff8146da5f>] setup_arch+0x48f/0x700
>  [<ffffffff802566ea>] ? clockevents_register_notifier+0x3a/0x50
>  [<ffffffff81466a87>] start_kernel+0xd7/0x440
>  [<ffffffff81466422>] x86_64_start_kernel+0x222/0x280
> 
> RIP 0x10
> 
> 
>  http://redhat.com/~mingo/misc/log-Wed_Apr_30_00_28_09_CEST_2008.bad
>  http://redhat.com/~mingo/misc/config-Wed_Apr_30_00_28_09_CEST_2008.bad
> 
> 	Ingo

Thanks, I'll check it out asap.

I might have to change the approach of the "remove pdas" patch a bit to
make it more "fail safe".

Thanks,
Mike

[PATCH 1/1] x86: leave initial __cpu_pda array in place until cpus are booted

[Mike Travis]

Ingo Molnar wrote:
...
> they crashed after about 3 randconfig iterations with:
> 
>   early res: 4 [8000-afff] PGTABLE
>   early res: 5 [b000-b87f] MEMNODEMAP
> PANIC: early exception 0e rip 10:ffffffff8077a150 error 2 cr2 37
> Pid: 0, comm: swapper Not tainted 2.6.25-sched-devel.git-x86-latest.git #14
> 
> Call Trace:
>  [<ffffffff81466196>] early_idt_handler+0x56/0x6a
>  [<ffffffff8077a150>] ? numa_set_node+0x30/0x60
>  [<ffffffff8077a129>] ? numa_set_node+0x9/0x60
>  [<ffffffff8147a543>] numa_init_array+0x93/0xf0
>  [<ffffffff8147b039>] acpi_scan_nodes+0x3b9/0x3f0
>  [<ffffffff8147a496>] numa_initmem_init+0x136/0x150
>  [<ffffffff8146da5f>] setup_arch+0x48f/0x700
>  [<ffffffff802566ea>] ? clockevents_register_notifier+0x3a/0x50
>  [<ffffffff81466a87>] start_kernel+0xd7/0x440
>  [<ffffffff81466422>] x86_64_start_kernel+0x222/0x280
...
Here's the fixup...  This one should follow the previous patches.

Thanks,
Mike
---
Subject: [PATCH 1/1] x86: leave initial __cpu_pda array in place until cpus are booted

  * The __cpu_pda table must be a set of NULL entries (except for the boot cpu)
    to indicate to numa_set_node during early system initialization that the
    cpu pdas are not yet setup.  The pda nodenumber is set later in pda_init().

Based on:
	git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6.git
    +   sched-devel/latest  .../mingo/linux-2.6-sched-devel.git


Signed-off-by: Mike Travis <travis@sgi.com>
---
 arch/x86/kernel/head64.c |   10 +++-------
 1 file changed, 3 insertions(+), 7 deletions(-)

--- linux-2.6.sched.orig/arch/x86/kernel/head64.c
+++ linux-2.6.sched/arch/x86/kernel/head64.c
@@ -29,17 +29,13 @@
 static struct x8664_pda _boot_cpu_pda __read_mostly;
 
 #ifdef CONFIG_SMP
-#ifdef CONFIG_DEBUG_PER_CPU_MAPS
 /*
- * We install an empty cpu_pda pointer table to trap references before
- * the actual cpu_pda pointer table is created in setup_cpu_pda_map().
+ * We install an empty cpu_pda pointer table to indicate to early users
+ * (numa_set_node) that the cpu_pda pointer table for cpus other than
+ * the boot cpu is not yet setup.
  */
 static struct x8664_pda *__cpu_pda[NR_CPUS] __initdata;
 #else
-static struct x8664_pda *__cpu_pda[1] __read_mostly;
-#endif
-
-#else /* !CONFIG_SMP (NR_CPUS will be 1) */
 static struct x8664_pda *__cpu_pda[NR_CPUS] __read_mostly;
 #endif