Re: [PoC] pg_upgrade: allow to upgrade publisher node

On Wed, Nov 8, 2023 at 8:44 AM vignesh C <vignesh21@gmail.com> wrote:
>
> While verifying upgrade of subscriber patch, I found one issue with
> upgrade in verbose mode.
> I was able to reproduce this issue by performing a upgrade with a
> verbose option.
>
> The trace for the same is given below:
> Program received signal SIGSEGV, Segmentation fault.
> __strlen_sse2 () at ../sysdeps/x86_64/multiarch/strlen-vec.S:126
> 126        ../sysdeps/x86_64/multiarch/strlen-vec.S: No such file or directory.
> (gdb) bt
> #0  __strlen_sse2 () at ../sysdeps/x86_64/multiarch/strlen-vec.S:126
> #1  0x000055555556f572 in dopr (target=0x7fffffffbb90,
> format=0x55555557859e "\", plugin: \"%s\", two_phase: %s",
> args=0x7fffffffdc40) at snprintf.c:444
> #2  0x000055555556ed95 in pg_vsnprintf (str=0x7fffffffbc10 "slot_name:
> \"ication slots within the database:", count=8192, fmt=0x555555578590
> "slot_name: \"%s\", plugin: \"%s\", two_phase: %s",
>     args=0x7fffffffdc40) at snprintf.c:195
> #3  0x00005555555667e3 in pg_log_v (type=PG_VERBOSE,
> fmt=0x555555578590 "slot_name: \"%s\", plugin: \"%s\", two_phase: %s",
> ap=0x7fffffffdc40) at util.c:184
> #4  0x0000555555566b38 in pg_log (type=PG_VERBOSE, fmt=0x555555578590
> "slot_name: \"%s\", plugin: \"%s\", two_phase: %s") at util.c:264
> #5  0x0000555555561a06 in print_slot_infos (slot_arr=0x555555595ed0)
> at info.c:813
> #6  0x000055555556186e in print_db_infos (db_arr=0x555555587518
> <new_cluster+120>) at info.c:782
> #7  0x00005555555606da in get_db_rel_and_slot_infos
> (cluster=0x5555555874a0 <new_cluster>, live_check=false) at info.c:308
> #8  0x000055555555839a in check_new_cluster () at check.c:215
> #9  0x0000555555563010 in main (argc=13, argv=0x7fffffffdf08) at
> pg_upgrade.c:136
>
> This issue occurs because we are accessing uninitialized slot array information.
>
> We could fix it by a couple of ways: a) Initialize the whole of
> dbinfos by using pg_malloc0 instead of pg_malloc which will ensure
> that the slot information is set to 0.
>

I would prefer this fix instead of initializing the slot array at
multiple places. I'll push this tomorrow unless someone thinks
otherwise.

-- 
With Regards,
Amit Kapila.