Re: [PATCHSET x86/core/percpu] improve the first percpu chunk allocation

[Yinghai Lu <yinghai@kernel.org>]

Ingo Molnar wrote:
> * Ingo Molnar <mingo@elte.hu> wrote:
> 
>>>   git://git.kernel.org/pub/scm/linux/kernel/git/tj/misc.git 
>>>   tj-percpu
>> ok, i pulled it into tip:core/percpu (one conflict resolution 
>> done - please double check it), and exposed it to -tip testing 
>> briefly.
>>
>> Six x86 test-systems failed ;-) One of them had this panic:
>>
>> Scan SMP from ffff880000000000 for 1024 bytes.
>> Scan SMP from ffff88000009fc00 for 1024 bytes.
>> Scan SMP from ffff8800000f0000 for 65536 bytes.
>> found SMP MP-table at [ffff8800000fe680] fe680
>> PANIC: early exception 0  rip   :                 error   cr2       
>> PANIC: early exception 0  rip   :                 error   cr2   
> 
> Ah, spoke too soon. Bisection gave this commit from Yinghai:
> 
> dc07da5: x86: check range in reserve_early()
> 

arh...

should be

diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c
index e858268..b114499 100644
--- a/arch/x86/kernel/e820.c
+++ b/arch/x86/kernel/e820.c
@@ -858,6 +858,9 @@ void __init reserve_early_overlap_ok(u64 start, u64 end, char *name)
  */
 void __init reserve_early(u64 start, u64 end, char *name)
 {
+	if (start >= end)
+		return;
+
 	drop_overlaps_that_are_ok(start, end);
 	__reserve_early(start, end, name, 0);
 }