Got it in FC22:
"SELinux is preventing systemd-logind from destroy access on the shared memory Unknown.

*****  Plugin catchall (100. confidence) suggests   **************************

If you believe that systemd-logind should be allowed destroy access on the Unknown shm by default.
Then you should report this as a bug.
You can generate a local policy module to allow this access.
Do
allow this access for now by executing:
# grep systemd-logind /var/log/audit/audit.log | audit2allow -M mypol
# semodule -i mypol.pp

Additional Information:
Source Context                system_u:system_r:systemd_logind_t:s0
Target Context                unconfined_u:unconfined_r:mozilla_plugin_t:s0-s0:c
                              0.c1023
Target Objects                Unknown [ shm ]
Source                        systemd-logind
Source Path                   systemd-logind
Port                          <Unknown>
Host                          localhost.localdomain
Source RPM Packages           
Target RPM Packages           
Policy RPM                    selinux-policy-3.13.1-128.19.fc22.noarch
Selinux Enabled               True
Policy Type                   targeted
Enforcing Mode                Enforcing
Host Name                     localhost.localdomain
Platform                      Linux localhost.localdomain 4.2.3-200.fc22.x86_64
                              #1 SMP Thu Oct 8 03:23:55 UTC 2015 x86_64 x86_64
Alert Count                   1
First Seen                    2015-10-17 03:13:55 EDT
Last Seen                     2015-10-17 03:13:55 EDT
Local ID                      426bf954-ea86-4cd4-99b9-fe12e363416d

Raw Audit Messages
type=AVC msg=audit(1445066035.452:597): avc:  denied  { destroy } for  pid=761 comm="systemd-logind" key=963154500  scontext=system_u:system_r:systemd_logind_t:s0 tcontext=unconfined_u:unconfined_r:mozilla_plugin_t:s0-s0:c0.c1023 tclass=shm permissive=0


Hash: systemd-logind,systemd_logind_t,mozilla_plugin_t,shm,destroy
"

Additional info:
selinux-policy-3.13.1-128.19.fc22.noarch
selinux-policy-targeted-3.13.1-128.19.fc22.noarch
kernel-4.2.3-200.fc22.x86_64

I don't remember what I was doing at the time.

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Fedora 21 changed to end-of-life (EOL) status on 2015-12-01. Fedora 21 is
no longer maintained, which means that it will not receive any further
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