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newDelta >0 failed in sqUnixMemory

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Damien Cassou-3

newDelta >0 failed in sqUnixMemory

Hi,

with a recent stock pharo image and a new VM compiled from svn on
Linux, I always get

squeak: /tmp/squeak-svn/platforms/unix/vm/sqUnixMemory.c:172:
uxGrowMemoryBy: Assertion `newDelta >= 0' failed.
Aborted

This does not happen on Squeak 3.9 nor 3.10. This did not happen
yesterday when I was on Ubuntu Hardy. Now, I'm on Intrepid, GCC 4.3.2
and it crashes after 3 seconds of work on any Pharo image.

You may want to know that to compile the vm, I was obliged to change
sqUnixFBDevMousePS2.c to make use of the 'write(2)' return value
because my compiler didn't want to compile if write(2) return value
was unused.

--
Damien Cassou
http://damiencassou.seasidehosting.st

Andreas.Raab

Re: newDelta >0 failed in sqUnixMemory

Since you're compiling the VM yourself, you might want to add a guard
that catches the condition and prints out the environmental values
(oldLimit, delta, newSize, newDelta). I would suspect that this is a
signed/unsigned issue with memory being allocated somewhere close to the
2GB barrier and then flipping from positive to negative. Since newSize
and newDelta are declared int, this could easily happen.

Cheers,
- Andreas

Damien Cassou wrote:

> Hi,
>
> with a recent stock pharo image and a new VM compiled from svn on
> Linux, I always get
>
> squeak: /tmp/squeak-svn/platforms/unix/vm/sqUnixMemory.c:172:
> uxGrowMemoryBy: Assertion `newDelta >= 0' failed.
> Aborted
>
> This does not happen on Squeak 3.9 nor 3.10. This did not happen
> yesterday when I was on Ubuntu Hardy. Now, I'm on Intrepid, GCC 4.3.2
> and it crashes after 3 seconds of work on any Pharo image.
>
> You may want to know that to compile the vm, I was obliged to change
> sqUnixFBDevMousePS2.c to make use of the 'write(2)' return value
> because my compiler didn't want to compile if write(2) return value
> was unused.
>

Damien Cassou-3

Re: newDelta >0 failed in sqUnixMemory

On Fri, Jan 30, 2009 at 9:00 AM, Andreas Raab <[hidden email]> wrote:
> Since you're compiling the VM yourself, you might want to add a guard that
> catches the condition and prints out the environmental values (oldLimit,
> delta, newSize, newDelta). I would suspect that this is a signed/unsigned
> issue with memory being allocated somewhere close to the 2GB barrier and
> then flipping from positive to negative. Since newSize and newDelta are
> declared int, this could easily happen.

I've just downgraded gcc to 3.4 (instead of 4.3.2) and it seems to
work fine. Do you want me to do more testing with the 4.3.2 version?

--
Damien Cassou
http://damiencassou.seasidehosting.st

Bert Freudenberg

Re: newDelta >0 failed in sqUnixMemory

In reply to this post by Damien Cassou-3

On 30.01.2009, at 08:47, Damien Cassou wrote:

> You may want to know that to compile the vm, I was obliged to change
> sqUnixFBDevMousePS2.c to make use of the 'write(2)' return value
> because my compiler didn't want to compile if write(2) return value
> was unused.

You're sure you're using the latest from SVN? What about this commit?

r1954 | piumarta | 2008-11-24 20:32:02 +0100 (Mo, 24 Nov 2008) | 1 line
Changed paths:
M /trunk/platforms/unix/ChangeLog
M /trunk/platforms/unix/vm-display-fbdev/sqUnixFBDevMousePS2.c
PS2 driver explicitly ignores the return value from write()

- Bert -

Andreas.Raab

Re: newDelta >0 failed in sqUnixMemory

In reply to this post by Damien Cassou-3

Damien Cassou wrote:

>
> On Fri, Jan 30, 2009 at 9:00 AM, Andreas Raab <[hidden email]> wrote:
>> Since you're compiling the VM yourself, you might want to add a guard that
>> catches the condition and prints out the environmental values (oldLimit,
>> delta, newSize, newDelta). I would suspect that this is a signed/unsigned
>> issue with memory being allocated somewhere close to the 2GB barrier and
>> then flipping from positive to negative. Since newSize and newDelta are
>> declared int, this could easily happen.
>
> I've just downgraded gcc to 3.4 (instead of 4.3.2) and it seems to
> work fine. Do you want me to do more testing with the 4.3.2 version?

I really don't care - I was just trying to give you a few hints for what
to look at. The other thing you could try is to compile with -O0 just to
find out whether this is an optimizer problem.

Cheers,
- Andreas

Damien Cassou-3

Re: newDelta >0 failed in sqUnixMemory

In reply to this post by Bert Freudenberg

On Fri, Jan 30, 2009 at 9:15 AM, Bert Freudenberg <[hidden email]> wrote:
> You're sure you're using the latest from SVN? What about this commit?

I'm sure because I did a checkout on a new directory. The line I
changed looked like:

(void) write(...);

It seems gcc 4.3.2 just ignores the (void) and consider the return value unused.

--
Damien Cassou
http://damiencassou.seasidehosting.st

David T. Lewis

Re: newDelta >0 failed in sqUnixMemory

In reply to this post by Damien Cassou-3

On Fri, Jan 30, 2009 at 09:14:33AM +0100, Damien Cassou wrote:

>
> On Fri, Jan 30, 2009 at 9:00 AM, Andreas Raab <[hidden email]> wrote:
> > Since you're compiling the VM yourself, you might want to add a guard that
> > catches the condition and prints out the environmental values (oldLimit,
> > delta, newSize, newDelta). I would suspect that this is a signed/unsigned
> > issue with memory being allocated somewhere close to the 2GB barrier and
> > then flipping from positive to negative. Since newSize and newDelta are
> > declared int, this could easily happen.
>
> I've just downgraded gcc to 3.4 (instead of 4.3.2) and it seems to
> work fine. Do you want me to do more testing with the 4.3.2 version?

Damien,

Yes, it would be helpful if you could find out more about what is
causing the bug when using gcc 4.3.2. It's probably the int declarations
as Andreas suggests, and it would be good if you can confirm this.

Thanks,
Dave

Damien Cassou-3

Re: newDelta >0 failed in sqUnixMemory

In reply to this post by Andreas.Raab

On Fri, Jan 30, 2009 at 9:00 AM, Andreas Raab <[hidden email]> wrote:
> Since you're compiling the VM yourself, you might want to add a guard that
> catches the condition and prints out the environmental values (oldLimit,
> delta, newSize, newDelta). I would suspect that this is a signed/unsigned
> issue with memory being allocated somewhere close to the 2GB barrier and
> then flipping from positive to negative. Since newSize and newDelta are
> declared int, this could easily happen.

Here is the result of:

fprintf(stderr, "oldLimit=%p\ndelta=%d\nnewSize=%d\nnewDelta=%d\n");

oldLimit=0x80562b8
delta=-1077506096
newSize=0
newDelta=423027548
squeak: /tmp/squeak-svn/platforms/unix/vm/sqUnixMemory.c:175:
uxGrowMemoryBy: Assertion `newDelta >= 0' failed.

Does it help?

--
Damien Cassou
http://damiencassou.seasidehosting.st

David T. Lewis

Re: newDelta >0 failed in sqUnixMemory

On Fri, Jan 30, 2009 at 02:07:33PM +0100, Damien Cassou wrote:

>
> On Fri, Jan 30, 2009 at 9:00 AM, Andreas Raab <[hidden email]> wrote:
> > Since you're compiling the VM yourself, you might want to add a guard that
> > catches the condition and prints out the environmental values (oldLimit,
> > delta, newSize, newDelta). I would suspect that this is a signed/unsigned
> > issue with memory being allocated somewhere close to the 2GB barrier and
> > then flipping from positive to negative. Since newSize and newDelta are
> > declared int, this could easily happen.
>
> Here is the result of:
>
> fprintf(stderr, "oldLimit=%p\ndelta=%d\nnewSize=%d\nnewDelta=%d\n");
>
> oldLimit=0x80562b8
> delta=-1077506096
> newSize=0
> newDelta=423027548
> squeak: /tmp/squeak-svn/platforms/unix/vm/sqUnixMemory.c:175:
> uxGrowMemoryBy: Assertion `newDelta >= 0' failed.
>
> Does it help?

Yes. I don't think newSize is supposed to be 0 here.

int newSize= min(valign(oldLimit - heap + delta), heapLimit);
int newDelta= newSize - heapSize;

I'm not sure what is wrong, but apparently it's in the expression
"min(valign(oldLimit - heap + delta), heapLimit)".

Dave

Andreas.Raab

Re: newDelta >0 failed in sqUnixMemory

David T. Lewis wrote:

>> fprintf(stderr, "oldLimit=%p\ndelta=%d\nnewSize=%d\nnewDelta=%d\n");
>>
>> oldLimit=0x80562b8
>> delta=-1077506096
>> newSize=0
>> newDelta=423027548
>> squeak: /tmp/squeak-svn/platforms/unix/vm/sqUnixMemory.c:175:
>> uxGrowMemoryBy: Assertion `newDelta >= 0' failed.
>>
>> Does it help?
>
> Yes. I don't think newSize is supposed to be 0 here.
>
> int newSize= min(valign(oldLimit - heap + delta), heapLimit);
> int newDelta= newSize - heapSize;
>
> I'm not sure what is wrong, but apparently it's in the expression
> "min(valign(oldLimit - heap + delta), heapLimit)".

Could be a CSE bug. Considering that min(a,b) is usually defined as "a <
b ? a : b" or so, a compiler might do something with the valign(...)
expression. I would try to move the expression out of there and see if
that helps.

Cheers,
- Andreas

Damien Cassou-3

Re: newDelta >0 failed in sqUnixMemory

On Fri, Jan 30, 2009 at 6:29 PM, Andreas Raab <[hidden email]> wrote:

>>> fprintf(stderr, "oldLimit=%p\ndelta=%d\nnewSize=%d\nnewDelta=%d\n");
>>>
>>> oldLimit=0x80562b8
>>> delta=-1077506096
>>> newSize=0
>>> newDelta=423027548
>>> squeak: /tmp/squeak-svn/platforms/unix/vm/sqUnixMemory.c:175:
>>> uxGrowMemoryBy: Assertion `newDelta >= 0' failed.
>>>
>>> Does it help?
>>
>> Yes. I don't think newSize is supposed to be 0 here.
>>
>> int newSize= min(valign(oldLimit - heap + delta), heapLimit);
>> int newDelta= newSize - heapSize;
>>
>> I'm not sure what is wrong, but apparently it's in the expression
>> "min(valign(oldLimit - heap + delta), heapLimit)".
>
> Could be a CSE bug. Considering that min(a,b) is usually defined as "a < b ?
> a : b" or so, a compiler might do something with the valign(...) expression.
> I would try to move the expression out of there and see if that helps.

Nobody noticed, but I did a very stupid mistake. Look at the call to
fprintf that I copy/pasted in my previous mail. I forgot all the
parameters :-). I don't how it is possible that gcc still compiled the
code...

I moved valign out:

int align = valign(oldLimit - heap + delta);
int newSize= min(align, heapLimit);

And printed the values:

if(newDelta < 0)
fprintf(stderr,
"oldLimit=%p\ndelta=%d\nnewSize=%d\nnewDelta=%d\nalign=%d\n",oldLimit,delta,newSize,newDelta,align);

And got:

oldLimit=0x791c8fe8
delta=0
newSize=23293952
newDelta=-4096
align=23293952
squeak: /tmp/squeak-svn/platforms/unix/vm/sqUnixMemory.c:175:
uxGrowMemoryBy: Assertion `newDelta >= 0' failed.
Aborted

Does that make sense to anyone?

--
Damien Cassou
http://damiencassou.seasidehosting.st

David T. Lewis

Re: newDelta >0 failed in sqUnixMemory

On Sat, Jan 31, 2009 at 11:15:02AM +0100, Damien Cassou wrote:

>
> On Fri, Jan 30, 2009 at 6:29 PM, Andreas Raab <[hidden email]> wrote:
> >>> fprintf(stderr, "oldLimit=%p\ndelta=%d\nnewSize=%d\nnewDelta=%d\n");
> >>>
> >>> oldLimit=0x80562b8
> >>> delta=-1077506096
> >>> newSize=0
> >>> newDelta=423027548
> >>> squeak: /tmp/squeak-svn/platforms/unix/vm/sqUnixMemory.c:175:
> >>> uxGrowMemoryBy: Assertion `newDelta >= 0' failed.
> >>>
> >>> Does it help?
> >>
> >> Yes. I don't think newSize is supposed to be 0 here.
> >>
> >> int newSize= min(valign(oldLimit - heap + delta), heapLimit);
> >> int newDelta= newSize - heapSize;
> >>
> >> I'm not sure what is wrong, but apparently it's in the expression
> >> "min(valign(oldLimit - heap + delta), heapLimit)".
> >
> > Could be a CSE bug. Considering that min(a,b) is usually defined as "a < b ?
> > a : b" or so, a compiler might do something with the valign(...) expression.
> > I would try to move the expression out of there and see if that helps.
>
> Nobody noticed, but I did a very stupid mistake. Look at the call to
> fprintf that I copy/pasted in my previous mail. I forgot all the
> parameters :-). I don't how it is possible that gcc still compiled the
> code...
>
> I moved valign out:
>
> int align = valign(oldLimit - heap + delta);
> int newSize= min(align, heapLimit);
>
> And printed the values:
>
> if(newDelta < 0)
> fprintf(stderr,
> "oldLimit=%p\ndelta=%d\nnewSize=%d\nnewDelta=%d\nalign=%d\n",oldLimit,delta,newSize,newDelta,align);
>
> And got:
>
> oldLimit=0x791c8fe8
> delta=0
> newSize=23293952
> newDelta=-4096
> align=23293952
> squeak: /tmp/squeak-svn/platforms/unix/vm/sqUnixMemory.c:175:
> uxGrowMemoryBy: Assertion `newDelta >= 0' failed.
> Aborted
>
> Does that make sense to anyone?

Something is going wrong in the call to valign. I can't quite
spot it, but note that valign(x) is {(x) & pageMask}, where pageMask
is 0xfffff000. Your newDelta result is -4096, which also happens
to be 0xfffff000.

Maybe as a next step you can break out the calculation further:
int argToAlign = oldLimit - heap + delta;
int align = valign(argToAlign);
int newSize= min(align, heapLimit);

Also printing the values of heap and heapLimit might give a clue.

Just a hunch, but I would guess that if you changed valign() from a
macro to a function that it would somehow decide to start working.

Dave

Damien Cassou-3

Re: newDelta >0 failed in sqUnixMemory

On Sat, Jan 31, 2009 at 5:55 PM, David T. Lewis <[hidden email]> wrote:
> Maybe as a next step you can break out the calculation further:
> int argToAlign = oldLimit - heap + delta;
> int align = valign(argToAlign);
> int newSize= min(align, heapLimit);
>
> Also printing the values of heap and heapLimit might give a clue.

int argToAlign = oldLimit - heap + delta;
int align = valign(argToAlign);
int newSize= min(align, heapLimit);
int newDelta= newSize - heapSize;
[...]
if(newDelta < 0)
fprintf(stderr,
"oldLimit=%p\ndelta=%d\nnewSize=%d\nnewDelta=%d\nalign=%d\nargToAlign=%d\nheap=%d\nheapLimit=%d\n",oldLimit,delta,newSize,newDelta,align,argToAlign,heap,heapLimit);

oldLimit=0x79288fe8
delta=0
newSize=23293952
newDelta=-4096
align=23293952
argToAlign=23298024
heap=2009403392
heapLimit=1073741824

--
Damien Cassou
http://damiencassou.seasidehosting.st

Damien Cassou-3

Re: newDelta >0 failed in sqUnixMemory

In reply to this post by David T. Lewis

On Sat, Jan 31, 2009 at 5:55 PM, David T. Lewis <[hidden email]> wrote:
> Just a hunch, but I would guess that if you changed valign() from a
> macro to a function that it would somehow decide to start working.

I used a function and get the following results.

int
myvalign(int x) {
return x & pageMask;
}

int argToAlign = oldLimit - heap + delta;
int align = myvalign(argToAlign);
int newSize= min(align, heapLimit);
int newDelta= newSize - heapSize;

oldLimit=0x7929cfe8
delta=0
newSize=23293952
newDelta=-4096
align=23293952
argToAlign=23298024
heap=2009485312
heapLimit=1073741824
squeak: /tmp/squeak-svn/platforms/unix/vm/sqUnixMemory.c:181:
uxGrowMemoryBy: Assertion `newDelta >= 0' failed.

--
Damien Cassou
http://damiencassou.seasidehosting.st

David T. Lewis

Re: newDelta >0 failed in sqUnixMemory

On Mon, Feb 02, 2009 at 12:28:49PM +0100, Damien Cassou wrote:

>
> On Sat, Jan 31, 2009 at 5:55 PM, David T. Lewis <[hidden email]> wrote:
> > Just a hunch, but I would guess that if you changed valign() from a
> > macro to a function that it would somehow decide to start working.
>
> I used a function and get the following results.
>
> int
> myvalign(int x) {
> return x & pageMask;
> }
>
> int argToAlign = oldLimit - heap + delta;
> int align = myvalign(argToAlign);
> int newSize= min(align, heapLimit);
> int newDelta= newSize - heapSize;
>
> oldLimit=0x7929cfe8
> delta=0
> newSize=23293952
> newDelta=-4096
> align=23293952
> argToAlign=23298024
> heap=2009485312
> heapLimit=1073741824
> squeak: /tmp/squeak-svn/platforms/unix/vm/sqUnixMemory.c:181:
> uxGrowMemoryBy: Assertion `newDelta >= 0' failed.

Hi Damien,

I'm not sure that I can be of much help here, but for what it's worth:

I copied the numbers from your test into a small stand alone test program
(attached for reference). The values that you printed all look reasonable,
and I think that the problem is probably *not* in the uxGrowMemoryBy()
function. The calculations up through newDelta all look correct, which
suggests that either heapSize (static var in sqUnixMemory.c) or oldLimit
(parameter to the function) are not set to the expected values. Of the two,
I would guess that the value of oldLimit is the more likely culprit, because
heapSize looks straightforward, while oldLimit is passed to the the unix
support code from ObjectMemory>>growObjectMemory: (translated Slang), and
goes through a pointerForOop() conversion along the way.

I'm completely guessing about the problem at this point, and obviously it
was related to the version of gcc you are using. Still, it's worth asking the
question, what version of VMMaker are you using?

Dave

checkUxGrowMemoryBy.c (1K) Download Attachment

Damien Cassou-3

Re: newDelta >0 failed in sqUnixMemory

On Wed, Feb 4, 2009 at 1:55 AM, David T. Lewis <[hidden email]> wrote:
> Still, it's worth asking the
> question, what version of VMMaker are you using?

I do not use VMMaker. I've just downloaded the sources from the
subversion repository and executed configure, make and make install in
a separate bld directory.

--
Damien Cassou
http://damiencassou.seasidehosting.st