This is a note to let you know that I've just added the patch titled
arch/sparc: support NR_CPUS = 4096
to the 4.11-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
arch-sparc-support-nr_cpus-4096.patch
and it can be found in the queue-4.11 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From foo@baz Thu Jun 8 08:58:43 CEST 2017
From: Jane Chu <jane.chu@xxxxxxxxxx>
Date: Tue, 6 Jun 2017 14:32:29 -0600
Subject: arch/sparc: support NR_CPUS = 4096
From: Jane Chu <jane.chu@xxxxxxxxxx>
[ Upstream commit c79a13734d104b5b147d7cb0870276ccdd660dae ]
Linux SPARC64 limits NR_CPUS to 4064 because init_cpu_send_mondo_info()
only allocates a single page for NR_CPUS mondo entries. Thus we cannot
use all 4096 CPUs on some SPARC platforms.
To fix, allocate (2^order) pages where order is set according to the size
of cpu_list for possible cpus. Since cpu_list_pa and cpu_mondo_block_pa
are not used in asm code, there are no imm13 offsets from the base PA
that will break because they can only reach one page.
Orabug: 25505750
Signed-off-by: Jane Chu <jane.chu@xxxxxxxxxx>
Reviewed-by: Bob Picco <bob.picco@xxxxxxxxxx>
Reviewed-by: Atish Patra <atish.patra@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/sparc/Kconfig | 4 ++--
arch/sparc/kernel/irq_64.c | 17 +++++++++++++----
2 files changed, 15 insertions(+), 6 deletions(-)
--- a/arch/sparc/Kconfig
+++ b/arch/sparc/Kconfig
@@ -192,9 +192,9 @@ config NR_CPUS
int "Maximum number of CPUs"
depends on SMP
range 2 32 if SPARC32
- range 2 1024 if SPARC64
+ range 2 4096 if SPARC64
default 32 if SPARC32
- default 64 if SPARC64
+ default 4096 if SPARC64
source kernel/Kconfig.hz
--- a/arch/sparc/kernel/irq_64.c
+++ b/arch/sparc/kernel/irq_64.c
@@ -1034,17 +1034,26 @@ static void __init init_cpu_send_mondo_i
{
#ifdef CONFIG_SMP
unsigned long page;
+ void *mondo, *p;
- BUILD_BUG_ON((NR_CPUS * sizeof(u16)) > (PAGE_SIZE - 64));
+ BUILD_BUG_ON((NR_CPUS * sizeof(u16)) > PAGE_SIZE);
+
+ /* Make sure mondo block is 64byte aligned */
+ p = kzalloc(127, GFP_KERNEL);
+ if (!p) {
+ prom_printf("SUN4V: Error, cannot allocate mondo block.\n");
+ prom_halt();
+ }
+ mondo = (void *)(((unsigned long)p + 63) & ~0x3f);
+ tb->cpu_mondo_block_pa = __pa(mondo);
page = get_zeroed_page(GFP_KERNEL);
if (!page) {
- prom_printf("SUN4V: Error, cannot allocate cpu mondo page.\n");
+ prom_printf("SUN4V: Error, cannot allocate cpu list page.\n");
prom_halt();
}
- tb->cpu_mondo_block_pa = __pa(page);
- tb->cpu_list_pa = __pa(page + 64);
+ tb->cpu_list_pa = __pa(page);
#endif
}
Patches currently in stable-queue which might be from jane.chu@xxxxxxxxxx are
queue-4.11/arch-sparc-support-nr_cpus-4096.patch