Re: [BUG] Logical replication failure "ERROR: could not map filenode "base/13237/442428" to relation OID" with catalog modifying txns

On Tue, Jul 12, 2022 at 5:58 PM shiy(dot)fnst(at)fujitsu(dot)com
<shiy(dot)fnst(at)fujitsu(dot)com> wrote:
>
> On Tue, Jul 12, 2022 8:49 AM Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com> wrote:
> >
> > I've attached an updated patch.
> >
>
> Hi,
>
> I met a segmentation fault in test_decoding test after applying the patch for master
> branch. Attach the backtrace.

Thank you for testing the patch!

>
> It happened when executing the following code because it tried to free a NULL
> pointer (catchange_xip).
>
> /* be tidy */
> if (ondisk)
> pfree(ondisk);
> + if (catchange_xip)
> + pfree(catchange_xip);
> }
>
> It seems to be related to configure option. I could reproduce it when using
> `./configure --enable-debug`.
> But I couldn't reproduce with `./configure --enable-debug CFLAGS="-Og -ggdb"`.

Hmm, I could not reproduce this problem even if I use ./configure
--enable-debug. And it's weird that we checked if catchange_xip is not
null but we did pfree for it:

#1 pfree (pointer=0x0) at mcxt.c:1177
#2 0x000000000078186b in SnapBuildSerialize (builder=0x1fd5e78,
lsn=25719712) at snapbuild.c:1792

Is it reproducible in your environment? If so, could you test it again
with the following changes?

diff --git a/src/backend/replication/logical/snapbuild.c
b/src/backend/replication/logical/snapbuild.c
index d015c06ced..a6e76e3781 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -1788,7 +1788,7 @@ out:
/* be tidy */
if (ondisk)
pfree(ondisk);
- if (catchange_xip)
+ if (catchange_xip != NULL)
pfree(catchange_xip);
}

Regards,

--
Masahiko Sawada
EDB: https://www.enterprisedb.com/