[PATCH 1/2] Account for module percpu space separately from kernel percpu

[PATCH 1/2] Account for module percpu space separately from kernel percpu

[Jeremy Fitzhardinge]

Rather than using a single constant PERCPU_ENOUGH_ROOM, compute it as
the sum of kernel_percpu + PERCPU_MODULE_RESERVE.  This is now common
to all architectures; if an architecture wants to set
PERCPU_ENOUGH_ROOM to something special, then it may do so (ia64 is
the only one which does).

Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Andi Kleen <ak@suse.de>

---
 include/asm-alpha/percpu.h   |   14 --------------
 include/asm-sparc64/percpu.h |   10 ----------
 include/asm-x86_64/percpu.h  |   10 ----------
 include/linux/percpu.h       |    9 ++++++++-
 init/main.c                  |    7 ++-----
 kernel/module.c              |    2 +-
 6 files changed, 11 insertions(+), 41 deletions(-)

===================================================================
--- a/include/asm-alpha/percpu.h
+++ b/include/asm-alpha/percpu.h
@@ -1,19 +1,5 @@
 #ifndef __ALPHA_PERCPU_H
 #define __ALPHA_PERCPU_H
-
-/*
- * Increase the per cpu area for Alpha so that
- * modules using percpu area can load.
- */
-#ifdef CONFIG_MODULES
-# define PERCPU_MODULE_RESERVE 8192
-#else
-# define PERCPU_MODULE_RESERVE 0
-#endif
-
-#define PERCPU_ENOUGH_ROOM \
-	(ALIGN(__per_cpu_end - __per_cpu_start, SMP_CACHE_BYTES) + \
-	 PERCPU_MODULE_RESERVE)
 
 #include <asm-generic/percpu.h>
 
===================================================================
--- a/include/asm-sparc64/percpu.h
+++ b/include/asm-sparc64/percpu.h
@@ -4,16 +4,6 @@
 #include <linux/compiler.h>
 
 #ifdef CONFIG_SMP
-
-#ifdef CONFIG_MODULES
-# define PERCPU_MODULE_RESERVE 8192
-#else
-# define PERCPU_MODULE_RESERVE 0
-#endif
-
-#define PERCPU_ENOUGH_ROOM \
-	(ALIGN(__per_cpu_end - __per_cpu_start, SMP_CACHE_BYTES) + \
-	 PERCPU_MODULE_RESERVE)
 
 extern void setup_per_cpu_areas(void);
 
===================================================================
--- a/include/asm-x86_64/percpu.h
+++ b/include/asm-x86_64/percpu.h
@@ -10,16 +10,6 @@
 #ifdef CONFIG_SMP
 
 #include <asm/pda.h>
-
-#ifdef CONFIG_MODULES
-# define PERCPU_MODULE_RESERVE 8192
-#else
-# define PERCPU_MODULE_RESERVE 0
-#endif
-
-#define PERCPU_ENOUGH_ROOM \
-	(ALIGN(__per_cpu_end - __per_cpu_start, SMP_CACHE_BYTES) + \
-	 PERCPU_MODULE_RESERVE)
 
 #define __per_cpu_offset(cpu) (cpu_pda(cpu)->data_offset)
 #define __my_cpu_offset() read_pda(data_offset)
===================================================================
--- a/include/linux/percpu.h
+++ b/include/linux/percpu.h
@@ -11,8 +11,15 @@
 
 /* Enough to cover all DEFINE_PER_CPUs in kernel, including modules. */
 #ifndef PERCPU_ENOUGH_ROOM
-#define PERCPU_ENOUGH_ROOM 32768
+#ifdef CONFIG_MODULES
+#define PERCPU_MODULE_RESERVE	8192
+#else
+#define PERCPU_MODULE_RESERVE	0
 #endif
+
+#define PERCPU_ENOUGH_ROOM						\
+	(__per_cpu_end - __per_cpu_start + PERCPU_MODULE_RESERVE)
+#endif	/* PERCPU_ENOUGH_ROOM */
 
 /*
  * Must be an lvalue. Since @var must be a simple identifier,
===================================================================
--- a/init/main.c
+++ b/init/main.c
@@ -369,11 +369,8 @@ static void __init setup_per_cpu_areas(v
 	unsigned long nr_possible_cpus = num_possible_cpus();
 
 	/* Copy section for each CPU (we discard the original) */
-	size = ALIGN(__per_cpu_end - __per_cpu_start, SMP_CACHE_BYTES);
-#ifdef CONFIG_MODULES
-	if (size < PERCPU_ENOUGH_ROOM)
-		size = PERCPU_ENOUGH_ROOM;
-#endif
+
+	size = ALIGN(PERCPU_ENOUGH_ROOM, SMP_CACHE_BYTES);
 	ptr = alloc_bootmem(size * nr_possible_cpus);
 
 	for_each_possible_cpu(i) {
===================================================================
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -430,7 +430,7 @@ static int percpu_modinit(void)
 	pcpu_size = kmalloc(sizeof(pcpu_size[0]) * pcpu_num_allocated,
 			    GFP_KERNEL);
 	/* Static in-kernel percpu data (used). */
-	pcpu_size[0] = -ALIGN(__per_cpu_end-__per_cpu_start, SMP_CACHE_BYTES);
+	pcpu_size[0] = -(__per_cpu_end-__per_cpu_start);
 	/* Free room. */
 	pcpu_size[1] = PERCPU_ENOUGH_ROOM + pcpu_size[0];
 	if (pcpu_size[1] < 0) {

Re: [PATCH 1/2] Account for module percpu space separately from kernel percpu

[Eric W. Biederman]

Jeremy Fitzhardinge <jeremy@goop.org> writes:

> Rather than using a single constant PERCPU_ENOUGH_ROOM, compute it as
> the sum of kernel_percpu + PERCPU_MODULE_RESERVE.  This is now common
> to all architectures; if an architecture wants to set
> PERCPU_ENOUGH_ROOM to something special, then it may do so (ia64 is
> the only one which does).

I think I have already done this but in case I haven't.
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>

I see any problems there.

Re: [PATCH 1/2] Account for module percpu space separately from kernel percpu

[Jeremy Fitzhardinge]

Eric W. Biederman wrote:
> I think I have already done this but in case I haven't.
> Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
>
> I see any problems there.
>   
^don't?

Re: [PATCH 1/2] Account for module percpu space separately from kernel percpu

[Eric W. Biederman]

Jeremy Fitzhardinge <jeremy@goop.org> writes:

> Eric W. Biederman wrote:
>> I think I have already done this but in case I haven't.
>> Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
>>
>> I see any problems there.
>>   
> ^don't?

Yep.  I did not see any problems with the patch.

Eric