Fedora is seeing a significantly reduced /proc/meminfo MemTotal with "debug" 5.11 series kernels. The problem isn't happening with "nodebug" kernels. The other possible instigator is GCC 11.0.0 is being used (all 5.10 series, nodebug and debug, are built with GCC 10.2.1). We're still doing some tests to narrow it down. The problem reproduces on x86_64 (no info on other archs yet) both baremetal and qemu-kvm. And first manifests with this line: 5.11.0-0.rc5.134.fc34.x86_64+debug Jan 28 13:56:08 flap.local kernel: Memory: 6547356K/8276392K available (43019K kernel code, 11036K rwdata, 27184K rodata, 5036K init, 31780K bss, 1728780K reserved, 0K cma-reserved) 5.11.0-0.rc5.134.fc34.x86_64 Jan 28 13:54:19 flap.local kernel: Memory: 7915056K/8276392K available (16393K kernel code, 3469K rwdata, 26796K rodata, 2544K init, 5484K bss, 361076K reserved, 0K cma-reserved) Reserved memory seems quite high in the debug case. Downstream bug report has dmesg for 5.11.0-0.rc5.134.fc34.x86_64+debug, and kernel config attachments. Bug 1921923 - Kernel under-reporting or hiding about a third of available memory in "debug" 5.11 series https://bugzilla.redhat.com/show_bug.cgi?id=1921923 -- Chris Murphy
