id = 2242
title = "Hugepages are not released after windows guest shutdown"
state = "closed"
created_at = "2024-03-23T13:39:39.079Z"
closed_at = "2024-08-01T08:05:18.773Z"
labels = ["Closed::NotOurBug"]
url = "https://gitlab.com/qemu-project/qemu/-/issues/2242"
host-os = "Gentoo Linux"
host-arch = "x86_64"
qemu-version = "QEMU emulator version 8.2.2"
guest-os = "Windows Server 2022 or Windows Server 2019"
guest-arch = "x86_64"
description = """* Hugepages are not released after windows guest shutdown (tested with server 2019 and 2022), everything is ok with linux guests
* Issue is present in both cases: shutdown is initiated by guest, and with the qemu monitor command ``system_shutdown``
* If the guest is configured with 4G as memory size, hugepages not released may vary but in most cases, only 1G are not released
* Host is a x86_64 linux system, with 1G hugepages only : kernel cmline contains ``default_hugepagesz=1G hugepagesz=1G hugepages=88``
* I've done many tests with qemu components disabled (network, monitor, vnc), issue is still present with basic command line (launched as root) ``qemu-system-x86_64 -cpu host -enable-kvm -smp 4 -machine type=q35,accel=kvm -m 4G -mem-path /mnt/hugepages -drive id=drv0,file=win.qcow2 -nodefaults``
* Same issue with args in command line, with or without prealloc:

        -m 4G -mem-path /mnt/hugepages [-mem-prealloc]
        -m 4G -machine memory-backend=mem0 -object memory-backend-memfd,id=mem0,size=4G,hugetlb=on,hugetlbsize=1G[,prealloc=on]"""
reproduce = "n/a"
additional = """* Hugepages release process is audited with command ``cat /proc/meminfo``
* I can't find any online documentation to help to troubleshoot used hugepages : articles suggest to audit /proc/[pid]/smaps, but here, issue is raised after qemu process terminates"""