Applies To
- Linux
- Linux Kernel v5.1 or later
- daxctl utility
- DAX System-RAM Feature
Issue
When attempting to offline a ‘system-ram’ device, daxctl returns an error similar to the following:
# daxctl offline-memory dax0.0
libdaxctl: offline_one_memblock: dax0.0: Failed to offline /sys/devices/system/node/node2/memory851/state: Device or resource busy
dax0.0: failed to offline memory: Device or resource busy
error offlining memory: Device or resource busy
Cause
One or more processes are using memory from the system-ram device, causing the ‘Device or resource busy’ error.
Solution
Use the fuser command to confirm if any processes are using the /dev/daxX.Y device. The following example shows many processes are still using the dax device:
# fuser -c /dev/dax0.0
/dev/dax0.0: 1 491rc 1576 1598 1914 2232 2234 2262 2267 2271 2272 2276 2277 2278 2281 2282 2290 2298 2308 2351 2369 2370 2371 2671 2674 2692 2695 2697 2698 2707 2981 2982 10018 10023 10025 10030
// Display process and owner
# fuser -cu /dev/dax0.0
/dev/dax0.0: 1(root) 491rc(root) 1576(root) 1598(root) 1914(root) 2232(root) 2234(root) 2262(root) 2267(root) 2271(root) 2272(root) 2276(root) 2277(root) 2278(root) 2281(root) 2282(root) 2290(dbus) 2298(root) 2308(dbus) 2351(polkitd) 2369(root) 2370(root) 2371(root) 2671(root) 2674(root) 2692(root) 2695(tomcat) 2697(root) 2698(root) 2707(root) 2981(dnsmasq) 2982(root) 10018(root) 10023(root) 10025(root) 10030(root)
Stop the application processes and try again, or schedule a system reboot.