man: fix ProcessSizeMax= description, describe how to disable coredumps

What the man page said was different than what the code did.
save_external_coredump() will store the core temporarily for backtrace
generation, and will delete if afterwards if it is too large. So to disable
processing, it's necessary to both set
Storage=none/Storage=journal+JournalSizeMax=0/Storage=external+ExternalSizeMax=0
and ProcessSizeMax=0. This updates the man page to reflect the code.

The man pages are extended to describe that Storage=none + ProcessSizeMax=0 is
the simplest way to disable coredump processing. All the storage and processing
options make this quite complicated, so let's add a copy-and-pasteable example
of how to disable coredump. Doing it through coredump.conf has the advantage
that we still log, and the effect is immediate, unlike masking the sysconf
file.

Fixes #8788.

diff --git a/man/coredump.conf.xml b/man/coredump.conf.xml
index 048bbc36370af301a3bb05365b38cdfd04d01f02..49debb219a33244befbb72b8d6037f8a8d23b3ad 100644 (file)
--- a/man/coredump.conf.xml
+++ b/man/coredump.conf.xml
@@ -74,7 +74,7 @@
 
         <listitem><para>Controls where to store cores. One of <literal>none</literal>,
         <literal>external</literal>, and <literal>journal</literal>. When
-        <literal>none</literal>, the core dumps will be logged (including the backtrace if
+        <literal>none</literal>, the core dumps may be logged (including the backtrace if
         possible), but not stored permanently. When <literal>external</literal> (the
         default), cores will be stored in <filename>/var/lib/systemd/coredump/</filename>.
         When <literal>journal</literal>, cores will be stored in the journal and rotated
@@ -101,8 +101,12 @@
 
         <listitem><para>The maximum size in bytes of a core
         which will be processed. Core dumps exceeding this size
-        will be logged, but the backtrace will not be generated
-        and the core will not be stored.</para></listitem>
+        may be stored, but the backtrace will not be generated.
+        </para>
+
+        <para>Setting <varname>Storage=none</varname> and <varname>ProcessSizeMax=0</varname>
+        disables all coredump handling except for a log entry.</para>
+        </listitem>
       </varlistentry>
 
       <varlistentry>

diff --git a/man/systemd-coredump.xml b/man/systemd-coredump.xml
index 6c3078143f3b23556bb7c02f56a26f9b7940c3bc..6fba19c22352ec1b84f4bce5cd817cf57fd6ace0 100644 (file)
--- a/man/systemd-coredump.xml
+++ b/man/systemd-coredump.xml
@@ -128,6 +128,16 @@
     core dumps and files can be set in files <filename>/etc/systemd/coredump.conf</filename> and snippets mentioned
     above. In addition the storage time of core dump files is restricted by <command>systemd-tmpfiles</command>,
     corresponding settings are by default in <filename>/usr/lib/tmpfiles.d/systemd.conf</filename>.</para>
+
+    <refsect2>
+      <title>Disabling coredump processing</title>
+
+      <para>To disable potentially resource-intensive processing by <command>systemd-coredump</command>,
+      set <programlisting>Storage=none
+ProcessSizeMax=0</programlisting> in
+      <citerefentry><refentrytitle>coredump.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
+      </para>
+    </refsect2>
   </refsect1>
 
   <refsect1>