Re: [scratch/igc] 985247b6bee crash on Linux, KDE, Wayland

[Eval EXEC <execvy@gmail.com>]

Eli Zaretskii <eliz@gnu.org> writes:

>> From: Eval EXEC <execvy@gmail.com>
>> Cc: pipcet@protonmail.com,  gerd.moellmann@gmail.com,  emacs-devel@gnu.org
>> Date: Fri, 06 Sep 2024 11:10:15 +0800
>> 
>> Eval EXEC <execvy@gmail.com> writes:
>> 
>> > I recompiled commit 95a30325a84 (HEAD -> scratch/igc, origin/scratch/igc)
>> > * src/igc.c (fix_frame): Correct the previous change.
>> >
>> > After testing, I believe the issue has been resolved.
>> 
>> scratch/igc 95a30325 crash again:
>> 
>> I use latest scratch/igc commit: * 95a30325a84 - (HEAD -> scratch/igc, origin/scratch/igc) * src/igc.c (fix_frame): Fix last change. (8 hours ago) <Eli Zaretskii>
>> 
>> #5  igc_assert_fail (file=<optimized out>, line=<optimized out>, msg=<optimized out>) at /home/exec/Projects/git.savannah.gnu.org/git/emacs/src/igc.c:209
>
> It's an assertion violation, and it's too bad 'msg' is "optimized
> out", because it's valuable information.
>
> This is a different problem, I think.
>
>> #9  0x0000000000690c05 in fix_lisp_obj (ss=ss@entry=0x7ffc7653e6f8, pobj=pobj@entry=0x7f08addd06b8) at /home/exec/Projects/git.savannah.gnu.org/git/emacs/src/igc.c:975
>>         off = <optimized out>
>>         client = <optimized out>
>>         base = 0x7f088a262a50
>>         res = <optimized out>
>>         new_off = <optimized out>
>>         p = 0x7f08addd06b8
>>         word = <optimized out>
>>         tag = <optimized out>
>>         _ss = 0x7ffc7653e6f8
>>         _mps_zs = <optimized out>
>>         _mps_ufs = 36029896530599944
>>         _mps_wt = <optimized out>
>>         _mps_w = <optimized out>
>> #10 0x00000000006919f8 in fix_cons (cons=0x7f08addd06b0, ss=0x7ffc7653e6f8) at /home/exec/Projects/git.savannah.gnu.org/git/emacs/src/igc.c:1751
>>         res = <optimized out>
>>         _ss = 0x7ffc7653e6f8
>>         _mps_zs = <optimized out>
>>         _mps_ufs = 36028797018972168
>>         _mps_wt = <optimized out>
>>         _mps_w = <optimized out>
>
> So this says we hit the trouble while fixing a car of a cons:
>
>   static mps_res_t
>   fix_cons (mps_ss_t ss, struct Lisp_Cons *cons)
>   {
>     MPS_SCAN_BEGIN (ss)
>     {
>       IGC_FIX12_OBJ (ss, &cons->u.s.car);  <<<<<<<<<<<<<<<<<<<<<
>       IGC_FIX12_OBJ (ss, &cons->u.s.u.cdr);
>     }
>     MPS_SCAN_END (ss);
>     return MPS_RES_OK;
>   }
>
>   static mps_res_t
>   fix_lisp_obj (mps_ss_t ss, Lisp_Object *pobj)
>   {
>     MPS_SCAN_BEGIN (ss)
>     {
>       mps_word_t *p = (mps_word_t *) pobj;
>       mps_word_t word = *p;
>
>       /* Quickly rule out Qnil, and prevent subtraxting from a
> 	 null pointer.  */
>       if (word == 0)
> 	return MPS_RES_OK;
>
>       mps_word_t tag = word & IGC_TAG_MASK;
>       if (tag == Lisp_Int0 || tag == Lisp_Int1)
> 	return MPS_RES_OK;
>       else if (tag == Lisp_Type_Unused0)
> 	emacs_abort ();
>
>       if (tag == Lisp_Symbol)
> 	{
> 	  ptrdiff_t off = word ^ tag;
> 	  mps_addr_t client = (mps_addr_t) ((char *) lispsym + off);
> 	  mps_addr_t base = client;
> 	  if (MPS_FIX1 (ss, base))
> 	    {
> 	      mps_res_t res = MPS_FIX2 (ss, &base); <<<<<<<<<<<<<<<<<<<
>
> I guess it would be interesting to see what was the cons and what was
> the symbol that was its car?
>
> Like this:
>
>   (gdb) frame 9
>   (gdb) p *pobj
>   (gdb) xtype
>   (gdb) xsymbol
>   (gdb) frame 10
>   (gdb) p *cons
>   (gdb) xcons
>   (gdb) p *xcons
>   (gdb) xcdr
>   (gdb) xtype
It's
(gdb) frame 9
#9  0x0000000000690c05 in fix_lisp_obj (ss=ss@entry=0x7ffc7653e6f8, pobj=pobj@entry=0x7f08addd06b8) at /home/exec/Projects/git.savannah.gnu.org/git/emacs/src/igc.c:975
975                 mps_res_t res = MPS_FIX2 (ss, &base);
(gdb) p *pobj
$1 = XIL(0x7f0889546b70)
(gdb) xtype
Lisp_Symbol
(gdb) xsymbol
$2 = (struct Lisp_Symbol *) 0x7f088a262a50
Cannot access memory at address 0x4c78
(gdb) frame 10
#10 0x00000000006919f8 in fix_cons (cons=0x7f08addd06b0, ss=0x7ffc7653e6f8) at /home/exec/Projects/git.savannah.gnu.org/git/emacs/src/igc.c:1751
1751        IGC_FIX12_OBJ (ss, &cons->u.s.car);
(gdb) p *cons
$3 = {
  gc_header = {
    v = 16630752781,
    gcaligned = 13 '\r'
  },
  u = {
    s = {
      car = XIL(0x7f0889546b70),
      u = {
        cdr = XIL(0x7f08936d87d3),
        chain = 0x7f08936d87d3
      }
    },
    gcaligned = 112 'p'
  }
}
(gdb) xcons
Invalid cast.
(gdb) p *xcons
No symbol "xcons" in current context.
(gdb) xcdr
Invalid cast.
(gdb) xtype
Invalid cast.

Thanks

Eval Exec

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