Work around unintelligent kernel OOM-kill algorithm.

postgresql-oom-adj.patch

@@ -0,0 +1,57 @@
+Back-ported patch from Postgres devel head: reset oom_adj to zero in any
+postmaster child process.  This allows us to disable OOM kill on the postmaster
+(see the init script) without affecting OOM behavior for child processes.
+
+
+diff -Naur postgresql-8.4.2.orig/src/backend/postmaster/fork_process.c postgresql-8.4.2/src/backend/postmaster/fork_process.c
+--- postgresql-8.4.2.orig/src/backend/postmaster/fork_process.c	2009-01-01 12:23:46.000000000 -0500
++++ postgresql-8.4.2/src/backend/postmaster/fork_process.c	2010-01-11 12:28:17.000000000 -0500
+@@ -12,7 +12,9 @@
+ #include "postgres.h"
+ #include "postmaster/fork_process.h"
+ 
++#include <fcntl.h>
+ #include <time.h>
++#include <sys/stat.h>
+ #include <sys/time.h>
+ #include <unistd.h>
+ 
+@@ -60,6 +62,38 @@
+ 		setitimer(ITIMER_PROF, &prof_itimer, NULL);
+ #endif
+ 
++		/*
++		 * By default, Linux tends to kill the postmaster in out-of-memory
++		 * situations, because it blames the postmaster for the sum of child
++		 * process sizes *including shared memory*.  (This is unbelievably
++		 * stupid, but the kernel hackers seem uninterested in improving it.)
++		 * Therefore it's often a good idea to protect the postmaster by
++		 * setting its oom_adj value negative (which has to be done in a
++		 * root-owned startup script).  If you just do that much, all child
++		 * processes will also be protected against OOM kill, which might not
++		 * be desirable.  You can then choose to build with LINUX_OOM_ADJ
++		 * #defined to 0, or some other value that you want child processes
++		 * to adopt here.
++		 */
++#ifdef LINUX_OOM_ADJ
++		{
++			/*
++			 * Use open() not stdio, to ensure we control the open flags.
++			 * Some Linux security environments reject anything but O_WRONLY.
++			 */
++			int		fd = open("/proc/self/oom_adj", O_WRONLY, 0);
++
++			/* We ignore all errors */
++			if (fd >= 0)
++			{
++				char	buf[16];
++
++				snprintf(buf, sizeof(buf), "%d\n", LINUX_OOM_ADJ);
++				(void) write(fd, buf, strlen(buf));
++				close(fd);
++			}
++		}
++#endif /* LINUX_OOM_ADJ */
+ 	}
+ 
+ 	return result;

postgresql.init

@@ -108,6 +108,8 @@ PGENGINE=/usr/bin
 PGPORT=5432
 PGDATA=/var/lib/pgsql/data
 PGLOG=/var/lib/pgsql/pgstartup.log
+# Value to set as postmaster process's oom_adj
+PG_OOM_ADJ=-17
 
 # Override defaults from /etc/sysconfig/pgsql if file is present
 [ -f /etc/sysconfig/pgsql/${NAME} ] && . /etc/sysconfig/pgsql/${NAME}
@@ -177,6 +179,7 @@ start(){
  	fi
 
 	echo -n "$PSQL_START"
+	test x"$PG_OOM_ADJ" != x && echo "$PG_OOM_ADJ" > /proc/self/oom_adj
 	$SU -l postgres -c "$PGENGINE/postmaster -p '$PGPORT' -D '$PGDATA' ${PGOPTS} &" >> "$PGLOG" 2>&1 < /dev/null
 	sleep 2
 	pid=`pidof -s "$PGENGINE/postmaster"`

postgresql.spec

@@ -53,7 +53,7 @@ Summary: PostgreSQL client programs
 Name: postgresql
 %global majorversion 8.4
 Version: 8.4.2
-Release: 3%{?dist}
+Release: 4%{?dist}
 # PostgreSQL calls their license simplified BSD, but the requirements are
 # more similar to other MIT licenses.
 License: MIT
@@ -74,6 +74,7 @@ Source17: http://www.postgresql.org/docs/manuals/postgresql-8.4.2-US.pdf
 Patch1: rpm-pgsql.patch
 Patch2: postgresql-ac-version.patch
 Patch3: postgresql-logging.patch
+Patch4: postgresql-oom-adj.patch
 Patch6: postgresql-perl-rpath.patch
 
 BuildRequires: perl(ExtUtils::MakeMaker) glibc-devel bison flex autoconf gawk
@@ -272,6 +273,7 @@ system, including regression tests and benchmarks.
 %patch1 -p1
 %patch2 -p1
 %patch3 -p1
+%patch4 -p1
 %patch6 -p1
 
 autoconf
@@ -281,10 +283,11 @@ cp -p %{SOURCE17} .
 %build
 
 CFLAGS="${CFLAGS:-%optflags}" ; export CFLAGS
-CXXFLAGS="${CXXFLAGS:-%optflags}" ; export CXXFLAGS
 
 # Strip out -ffast-math from CFLAGS....
 CFLAGS=`echo $CFLAGS|xargs -n 1|grep -v ffast-math|xargs -n 100`
+# Add LINUX_OOM_ADJ=0 to ensure child processes reset postmaster's oom_adj
+CFLAGS="$CFLAGS -DLINUX_OOM_ADJ=0"
 # let's try removing this kluge, it may just be a workaround for bz#520916
 # # use -O1 on sparc64 and alpha
 # %ifarch sparc64 alpha
@@ -693,6 +696,11 @@ rm -rf $RPM_BUILD_ROOT
 %endif
 
 %changelog
+* Mon Jan 11 2010 Tom Lane <tgl@redhat.com> 8.4.2-4
+- Arrange for the postmaster, but not any of its child processes, to be run
+  with oom_adj -17.  This compensates for the OOM killer not being smart about
+  accounting for shared memory usage.
+
 * Sat Jan  9 2010 Tom Lane <tgl@redhat.com> 8.4.2-3
 - Remove the postgresql-python and postgresql-tcl subpackages.  These files
   are now broken out as their own packages (PyGreSQL and tcl-pgtcl,