Subject: Re: bug#78444: 30.1; Crash in GC (vector_marked_p)

From: George P <[email-masked]>
Date: Sun, 18 May 2025 11:12:43 -0400

>
> Can you please run x/64gx 0x3aa1ac0 so we can be sure
> of this?
>

Sure:

(gdb) x/64gx 0x3aa1ac0
0x3aa1ac0:      0x00000000098f1d0d      0x0000000000000030
0x3aa1ad0:      0x00000000098f1d65      0x0000000000000030
0x3aa1ae0:      0x00000000098f1dbd      0x0000000000000030
0x3aa1af0:      0x00000000098f1e15      0x0000000000000030
0x3aa1b00:      0x00000000098f1e6d      0x0000000000000030
0x3aa1b10:      0x00000000098f1ec5      0x0000000000000030
0x3aa1b20:      0x00000000098f1f1d      0x0000000000000030
0x3aa1b30:      0x00000000098f1f75      0x0000000000000030
0x3aa1b40:      0x00000000098f1fcd      0x0000000000000030
0x3aa1b50:      0x00000000098f2025      0x0000000000000030
0x3aa1b60:      0x00000000098f207d      0x0000000000000030
0x3aa1b70:      0x00000000098f20d5      0x0000000000000030
0x3aa1b80:      0x00000000098f212d      0x0000000000000030
0x3aa1b90:      0x00000000098f2185      0x0000000000000030
0x3aa1ba0:      0x00000000098f21dd      0x0000000000000030
0x3aa1bb0:      0x00000000098f2235      0x0000000000000030
0x3aa1bc0:      0x00000000098f228d      0x0000000000000030
0x3aa1bd0:      0x00000000098f22e5      0x0000000000000030
0x3aa1be0:      0x00000000098f233d      0x0000000000000030
0x3aa1bf0:      0x00000000098f2395      0x0000000000000030
0x3aa1c00:      0x00000000098f23ed      0x0000000000000030
0x3aa1c10:      0x00000000098f2445      0x0000000000000030
0x3aa1c20:      0x00000000098f249d      0x0000000000000030
0x3aa1c30:      0x00000000098f24f5      0x0000000000000030
0x3aa1c40:      0x00000000098f254d      0x0000000000000030
0x3aa1c50:      0x00000000098f25a5      0x0000000000000030
0x3aa1c60:      0x0000000000000007      0x0000000000000007
0x3aa1c70:      0x0000000000000007      0x0000000000000007
0x3aa1c80:      0x0000000000000007      0x0000000000000007
0x3aa1c90:      0x0000000000000007      0x0000000000000007
0x3aa1ca0:      0x0000000000000007      0x0000000000000007
0x3aa1cb0:      0x0000000000000007      0x0000000000000007
(gdb)

Keep them coming! Are you still suspecting X?

Thanks!
George

On Sat, May 17, 2025 at 5:17 PM Pip Cet <[email-masked]> wrote:

> "George P" <[email-masked]> writes:
>
> >  Can you try this (subtracting 5 from the tagged pointer to get the base
> >  pointer, then printing its memory region):
> >
> >       x/32gx 0x98e79d8
> >       x/32gx 0x98f1d08
> >
> > (gdb) x/32gx 0x98e79d8
> > 0x98e79d8:      0xc00000000e008000      0x0000000020e10970
> > 0x98e79e8:      0x0000000003aa20d0      0x0000000003aa1ac0
> > 0x98e79f8:      0x00000000006e9960      0x000000002265f480
> > 0x98e7a08:      0x0000001a0000001a      0x0000400700000060
> > 0x98e7a18:      0x0000000000000000      0x400000000e008000
> > 0x98e7a28:      0x000000001bfdbe90      0x0000000020e10b80
> > 0x98e7a38:      0x000000001bfdb880      0x00000000006e98e0
> > 0x98e7a48:      0x000000001fd792e0      0x0000001a0000001a
> > 0x98e7a58:      0x0000400700000060      0x0000000000000000
> > 0x98e7a68:      0x400000001f000005      0x0000000000000606
> > 0x98e7a78:      0x0000000008ae5654      0x000000001b78fe2d
> > 0x98e7a88:      0x0000000000000012      0x0000000008ae5674
> > 0x98e7a98:      0x400000001f000005      0x0000000000000606
> > 0x98e7aa8:      0x0000000008ae5694      0x000000001c32b8dd
> > 0x98e7ab8:      0x000000000000000e      0x0000000008ae5674
> > 0x98e7ac8:      0x000000000000000e      0x000015554de5d450
>
> This tells us the stale pointer was most likely found in a hash table,
> with 26 elements.  Can you please run x/64gx 0x3aa1ac0 so we can be sure
> of this?
>
> Unfortunately, most likely, all that is going to tell us the basic types
> of the keys and values in the hash table, and we're then going to have
> to investigate the surviving keys and values to get a clue as to what
> the hash table might have been.  Unless someone can think of a better
> way?
>
> Thanks again!
>
> Pip
>
>