On Mon, 2015-01-19 at 16:49 -0500, Steven Rostedt wrote: > 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 <ying...@kernel.org> > 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.
Yes, I know this needs fixing. It also broke suspend/resume on SMP machines since that involves offlining and onlining CPUs 1-n. Ben. > Signed-off-by: Steven Rostedt <rost...@goodmis.org> > --- > 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(); > -- Ben Hutchings Larkinson's Law: All laws are basically false.
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