Re: 3.4-rc7: BUG: Bad rss-counter state mm:ffff88040b56f800 idx:1 val:-59

[Konstantin Khlebnikov <khlebnikov@openvz.org>]

Martin Mokrejs wrote:
> Andrew Morton wrote:
>> On Wed, 30 May 2012 00:18:31 +0400
>> Konstantin Khlebnikov<khlebnikov@openvz.org>  wrote:
>>
>>> Oleg Nesterov wrote:
>>>> On 05/22, Andrew Morton wrote:
>>>>>
>>>>> Also, I have a note here that Oleg was unhappy with the patch.  Oleg
>>>>> happiness is important.  Has he cheered up yet?
>>>>
>>>> Well, yes, I do not really like this patch ;) Because I think there is
>>>> a more simple/straightforward fix, see below. In my opinion it also
>>>> makes the original code simpler.
>>>>
>>>> But. Obviously this is subjective, I can't prove my patch is "better",
>>>> and I didn't try to test it.
>>>>
>>>> So I won't argue with Konstantin who dislikes my patch, although I
>>>> would like to know the reason.
>>>
>>> I don't remember why I dislike your patch.
>>> For now I can only say ACK )
>>
>> We'll need a changelogged signed-off patch, please Oleg.  And some evidence
>> that it was tested would be nice ;)
>
> I will reboot in few hours, finally after few days ... I am running this first
> patch. I will try to test the second/alternative patch more quickly. Sorry for
> the delay.
>

easiest way trigger this bug:

#define _GNU_SOURCE
#include <unistd.h>
#include <sched.h>
#include <sys/syscall.h>
#include <sys/mman.h>

static inline int sys_clone(unsigned long flags, void *stack, int *ptid, int *ctid)
{
	return syscall(SYS_clone, flags, stack, ptid, ctid);
}

int main(int argc, char **argv)
{
	void *page;

	page = mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
	sys_clone(CLONE_VFORK | CLONE_VM | CLONE_CHILD_CLEARTID, NULL, NULL, page);
}

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