Обсуждение: pgsql: Fix broken mmap failure-detection code, and improve error messag

Fix broken mmap failure-detection code, and improve error message.

Per an observation by Thom Brown that my previous commit made an
overly large shmem allocation crash the server, on Linux.

Branch
------
master

Details
-------
http://git.postgresql.org/pg/commitdiff/39715af23ae459684963c350dd69eafa2d502e7e

Modified Files
--------------
src/backend/port/sysv_shmem.c |   13 ++++++++++---
1 files changed, 10 insertions(+), 3 deletions(-)