Re: [LTP] clone tests fails

[Michal Simek <michal.simek@petalogix.com>]

Jiri Palecek wrote:
> Serge E. Hallyn napsal(a):
>> Quoting Michal Simek (michal.simek@petalogix.com):
>>> Serge E. Hallyn wrote:
>>>> Quoting Michal Simek (michal.simek@petalogix.com):
>>>>> Hi Mike,
>>>>>
>>>>> I have one question about one your big patch
>>>>>
>>>>> http://git.kernel.org/?p=linux/kernel/git/galak/ltp.git;a=commitdiff;h=391dc18fe3271fbf2ca1864a5299f091c31e0018 
>>>>>
>>>>>
>>>>> My question is why you add -1 in lib/cloner.c:65
>>>>>
>>>>> +       ret = clone(fn, (stack ? stack + stack_size - 1 : NULL),
>>>>> +                       clone_flags, arg);
>>>>>
>>>>> In previous code in clone testcases was nothing like this.
>>>>> What reason have you had to add it?
>>>>
>>>> Because the same thing was done in lots of places all over the
>>>> testsuite (and done wrong).  This consolidates them all.
>>>
>>>
>>> I don't have anything against consolidation. I just want to know why
>>> there is that -1 which weren't in any clone testcases. Nothing more
>>> nothing less.
>>
>> ooooh.  Because if we've done stack = malloc(stack_size), then
>> stack+stack_size is 1 above the the top of stack.
> 
> If the value of the parameter is the stack pointer of the created 
> thread, it shouldn't matter - the address should never be used (read or 
> written).
> 
> Michal, I suspect the failures you see are somehow related to alignment 
> (that your architecture doesn't like odd addresses). Is that right? 
> Under x86, the address gets aligned (so some of the space is unused).

yes, alignment is problem. I need to subtract at least -4.

As you can see below I am getting fault in kernel about task_size exceed.

# ./clone01
kernel task_size exceed, 0xffffffff, 0xc0000000
Oops: Exception in kernel mode, sig: 11
  Registers dump: mode=1
  r1=CDC3FF50, r2=00000000, r3=000008A1, r4=FFFFFFFF
  r5=00000000, r6=00000800, r7=CDC3FF68, r8=00000028
  r9=481804AC, r10=00000000, r11=000045AA, r12=C00011C4
  r13=00000000, r14=6B6B6B6B, r15=C00083F8, r16=6B6B6B6B
  r17=6B6B6B6B, r18=00000000, r19=FFFFFFFF, r20=100074C8
  r21=00000000, r22=100073CC, r23=00000000, r24=00000000
  r25=1000C050, r26=00000001, r27=10005310, r28=10001060
  r29=00000000, r30=00000000, r31=CDD4C358, rPC=C00011DC
  msr=000045AA, ear=FFFFFFFF, esr=000000B2, fsr=10005310
clone01     1  TPASS  :  clone() returned 66

Michal


> 
> Perhaps both of these behaviors should be tested by LTP?
> 
> Regards
>     Jiri Palecek


-- 
Michal Simek, Ing. (M.Eng)
PetaLogix - Linux Solutions for a Reconfigurable World
w: www.petalogix.com p: +61-7-30090663,+42-0-721842854 f: +61-7-30090663

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