On 1/12/23 11:31, Maxim Levitsky wrote: > On Thu, 2023-01-12 at 07:07 +0100, Jiri Slaby wrote: >> >> I have rebooted to a fresh kernel which 1) have lockdep enabled, and 2) >> I have debuginfo for. So next time this happens, I can print held locks >> and dump a kcore (kdump is set up). >> >> regards, > > It is also possible that I noticed something like that on 6.1: > > For me it happens when my system (also no swap, 96G out which 48 are permanetly reserved as 1G hugepages, > and this happens with VMs which don't use this hugepage reserve) > is somewhat low on memory and qemu tries to lock all memory (I use -overcommit mem-lock=on) > > Like it usually happens when I start 32 GB VM while having lot of stuff open in background, but > still not nearly close to 16GB. > As a workaround I lowered the reserved area to 32G. > > I also see indication that things like htop or even opening a new shell hang quite hard. > > What almost instantly helps is 'echo 3 | sudo tee /proc/sys/vm/drop_caches' > e.g that makes the VM start booting, and unlocks everything. Note it's possible that temporary+recoverable things like that have a different cause caused by compaction caught in a loop, as discussed here: https://lore.kernel.org/all/a032e3bf-8470-095a-2262-791f5678e590@xxxxxxx/ > Best regards, > Maxim Levitsky >
