Testing v3.2-rt I found that after merging the latest v3.2 stable tree,
hotplug stopped working. I tested the latest v3.2 stable, and it was
not working there either. I bisected it down to:
commit e105c8187b7101e8a8a54ac0218c9d9c9463c636
Author: Yinghai Lu <yinghai@xxxxxxxxxx>
Date: Thu Jan 24 12:20:13 2013 -0800
x86, 64bit, mm: Mark data/bss/brk to nx
commit 72212675d1c96f5db8ec6fb35701879911193158 upstream.
Simply doing:
# echo 0 > /sys/devices/system/cpu/cpu1/online
# echo 1 > /sys/devices/system/cpu/cpu1/online
caused the system to reboot.
After reverting that commit, hotplug works again on the v3.2 stable
tree.
Signed-off-by: Steven Rostedt <rostedt@xxxxxxxxxxx>
---
diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
index 266f71719e42..783eba48d00c 100644
--- a/arch/x86/mm/init_64.c
+++ b/arch/x86/mm/init_64.c
@@ -778,7 +778,6 @@ void mark_rodata_ro(void)
unsigned long text_end = PAGE_ALIGN((unsigned long) &__stop___ex_table);
unsigned long rodata_end = PAGE_ALIGN((unsigned long) &__end_rodata);
unsigned long data_start = (unsigned long) &_sdata;
- unsigned long all_end;
printk(KERN_INFO "Write protecting the kernel read-only data: %luk\n",
(end - start) >> 10);
@@ -787,8 +786,8 @@ void mark_rodata_ro(void)
kernel_set_to_readonly = 1;
/*
- * The rodata/data/bss/brk section (but not the kernel text!)
- * should also be not-executable.
+ * The rodata section (but not the kernel text!) should also be
+ * not-executable.
*
* We align all_end to PMD_SIZE because the existing mapping
* is a full PMD. If we would align _brk_end to PAGE_SIZE we
@@ -798,8 +797,7 @@ void mark_rodata_ro(void)
* Any PMD which was setup after the one which covers _brk_end
* has been zapped already via cleanup_highmem().
*/
- all_end = roundup((unsigned long)_brk_end, PMD_SIZE);
- set_memory_nx(rodata_start, (all_end - rodata_start) >> PAGE_SHIFT);
+ set_memory_nx(rodata_start, (end - rodata_start) >> PAGE_SHIFT);
rodata_test();
--
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