Horton

Re: some question about _bt_getbuf

Tom Lane <tgl@sss.pgh.pa.us>

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: 自己 <zoulx1982@163.com>
Cc: "pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>, Simon Riggs <simon@2ndquadrant.com>
Date: 2018-05-14T17:49:41Z
Lists: pgsql-hackers 
=?GBK?B?19S8ug==?= <zoulx1982@163.com> writes:
> i run test using pg10.0 on my machine, and the program crashed on _bt_getbuf.
> And i found the following code:
> the routine _bt_page_recyclable say maybe the page is all-zero page, if so
> then the code run (BTPageOpaque) PageGetSpecialPointer(page); it will be failed because
> it access invalid memory.
> I don't know whether it is so. Look forward t your reply, thanks.

This code's clearly broken, as was discussed before:

https://www.postgresql.org/message-id/flat/2628.1474272158%40localhost

but nothing was done about it, perhaps partly because we didn't have
a reproducible test case.  Do you have one?

			regards, tom lane

Commits

  1. Avoid emitting a bogus WAL record when recycling an all-zero btree page.