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

[Martin Mokrejs <mmokrejs@fold.natur.cuni.cz>]

Konstantin Khlebnikov wrote:
> 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);
> }
> 

I am getting segfaults with this.

(gdb) where
#0  0x0000000000000000 in ?? ()
#1  0x00007f430f70a7e0 in __elf_set___libc_subfreeres_element_free_mem__ () from /lib64/libc.so.6
#2  0x00007f430f70a7e8 in __elf_set___libc_atexit_element__IO_cleanup__ () from /lib64/libc.so.6
#3  0x0000000000000001 in ?? ()
#4  0x0000000000000000 in ?? ()
(gdb)

What number should I give it as an argument? ;-)

Martin

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