The 4.19-rt patch,
0329-signal-Prevent-double-free-of-user-struct.patch
needs to be ported to LAG 4.9-rt, as that release now has the Linus commit,
fda31c50292a ("signal: avoid double atomic counter increments for user accounting")
which breaks the longstanding rt patch,
0259-signals-Allow-rt-tasks-to-cache-one-sigqueue-struct.patch
Current application status:
4.4.302-rt232 OK has both Linus's patch and the fix needed for rt.
4.9.312-rt193 BROKE has Linus's patch but not the fix.
4.14.87-rt50 OK does NOT have either Linus's patch nor its rt fix.
4.19.246-rt110 OK has both Linus's patch and the fix needed for rt.
5.4.193-rt74 OK has both Linus's patch and the fix needed for rt.
5.10.120-rt70 OK has both Linus's patch and the fix needed for rt.
5.15.44-rt46 UNKNOWN no get_uid/free_uid usage in kernel/signal.c anymore.
Regards,
Joe