Versions prior to gdb-7.6.1-83.el7, unconditionally included all memory regions when generating a dump file. Starting with this version, by default GDB will both inspect /proc/PID/coredump_filter, and unconditionally ignore memory regions marked with VM_DONTDUMP.
While it's possible requesting to GDB to ignore /proc/PID/coredump_filter by using the 'set use-coredump-filter' command, there's no way to request it to ignore the VM_DONTDUMP flag.
The change that altered the behavior is this one:
Author: Jan Kratochvil <jan.kratochvil>
Date: Fri Nov 27 20:43:41 2015 +0100
Support for /proc/PID/coredump_filter (Sergio Durigan Junior, RH
Sergio Durigan Junior, RH BZ 1265351
- Resolves: rhbz#1265351
I've posted a tentative fix for this upstream:
Reproduced against gdb-7.6.1-100.el7 and verified against gdb-7.6.1-108.el7.
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.
For information on the advisory, and where to find the updated
files, follow the link below.
If the solution does not work for you, open a new bug report.