On Thu, Sep 19, 2019 at 08:10:47AM -0700, Dan Williams wrote:
On Thu, Sep 19, 2019 at 4:56 AM Adam Borowski
> If I try to change the mode of a devdax namespace that's in use (mapped by
> some process), ndctl hangs:
Is it merely mapped, or might the pages be actively pinned / in use by
another part of the kernel? The kernel has no choice but to wait for
active page pins to drain. Can you get a stack trace of the process
with the dev-dax instance mapped?
Looks like the behaviour is different depending on what the other process
* with qemu, the hang is 100% reproducible, the guest continues to work and
cleanly exits -- qemu does not exit on its own (unlike normal case) but
SIGTERM terminates it correctly. Thus, qemu is not stuck, only ndctl is.
* with mere mmap() (I've used vmemcache) ndctl allows
reconfiguring the namespace. No hang.
My way to start qemu is:
NET="-net bridge -net nic"
exec qemu-system-x86_64 -enable-kvm -m 4096,slots=2,maxmem=16G -smp 8 $NET \
-drive if=none,id=hd,file="$DISK",format=raw,cache=unsafe,discard=on \
-device virtio-scsi-pci,id=scsi -device scsi-hd,drive=hd \
-M pc,nvdimm,nvdimm-persistence=mem-ctrl \
-device nvdimm,id=nvdimm1,memdev=mem1,label-size=256K \
⢀⣴⠾⠻⢶⣦⠀ A MAP07 (Dead Simple) raspberry tincture recipe: 0.5l 95% alcohol,
⣾⠁⢠⠒⠀⣿⡁ 1kg raspberries, 0.4kg sugar; put into a big jar for 1 month.
⢿⡄⠘⠷⠚⠋⠀ Filter out and throw away the fruits (can dump them into a cake,
⠈⠳⣄⠀⠀⠀⠀ etc), let the drink age at least 3-6 months.