VM Ware Fusion potentially causes macOS 10.15.6 to crash

[Alex_Ma]

I recently upgraded to macOS 10.15.6. Now if I leave VM Ware Fusion running while leaving my mac for some time, e.g. - for a night, the system crashes. This did not happen with the older macOS 10.15.5 version.

VM Ware Fusion version: Professional Version 11.5.5 (16269456)

macOS Catalina version: 10.15.6 (19G73)

[Jadraker]

The problem is worse than I thought. I had not restarted my Mac for two days and every time I occupied the VM I suspended it thinking that this would avoid the problem. Today I suspended the VM, started doing other things and had a KP. Then, every time I started Mac, it would freeze trying to load what was open before. At third reboot I had to select to not reload the programs from the previous session in order to be able re-occupy the computer.

It is useless to suspend VMs, you have to periodically restart the host. What a nightmare of update...

[Alex_Ma]

Right. That's what I am saying - the memory gets corrupted somewhere. I experienced the same issue. At least when VM is down, the guest OS does not need a reboot.

[ColoradoMarmot]

Unfortunately, I have too much data to use a time machine rollback.  I was able to get a hold of the 10.15.5 installer from someone who had it archived, and did an overlay install - that reverted the system back and everything seems stable.

Moral of the story - download the installers every time apple releases a dot update.

[Jadraker]

Yes, that's right. With suspend I mean the "pause" button of Fusion not the sleep function of guest OS. I thought that when you suspend a VM all of its RAM content was dumped to a drive file but apparently something is not released from RAM and KP again. So guys a complete reboot is needed in order to avoid issues.

[Alex_Ma]

mmm... I guess macOS Catalina 10.15.5 Combo Update might work? I'll check this out to see if it works. Downloading now...

[pelletierr]

It will not work.

You need to get the full installer and over install that version over 10.15.6.

[jerryfrit]

Everyone's mileage will vary, but running the full installer made no difference for me.  In fact, I did that before this, apparently my very issue, came up in the Fusion (also VirtualBox) forums.  Since then, I'm just taking a wait-and-see as to how Apple responds to this report.

[dariusd]

Hi everyone,

Quick status report:

I expect Apple is working on a fix, but I have no insight into their release process or timelines, and there are simply too many variables at play to even guess at how long it will be before a fix is released.  We are all hoping it will arrive soon!  I have no news to share on the possibility of working around it within Fusion, either.

To address some of the other topics that have popped up in this discussion:

The defect is likely to severely affect virtualization/emulation software which does not use Apple's Hypervisor.framework to do the low-level work.  The same defect could theoretically affect other non-virtualization/non-emulation software too, but I have not confirmed this possibility, and in any case it is unlikely to be anywhere near as severe as for virtualization/emulation... The most likely affected might include: software accompanying "unusual" hardware with its own kext, perhaps Intel HAXM, Android emulators, VPN or network tunneling software, antivirus/antimalware software.  If you are encountering this memory leak problem even when you are not using Fusion, there's a chance it could possibly be triggered by some other software package.

The memory leak is in the kernel, so the only way to free things up is restarting your Mac.  Suspending/resuming your VM will not help in any meaningful way, nor will quitting and relaunching Fusion.

I do not personally have any specific advice regarding approaches to downgrading macOS... I have not had a need to do that in many, many years!  My own preference would probably be to try to stick it out on macOS 10.15.6, simply based upon the unknown potential for headaches with the downgrade process... but I appreciate that there will be plenty of you for whom that is not an option, particularly with the mystery timeline for the fix.

Thanks,

--

Darius

[wila]

Nope, just did that yesterday.

Restore from the internet -> puts you on 10.15.6.

--

Wil

[michelstoffel]

Just for your info, my computer always crash after i come back the lunch (1 hour) or after continue hours (7-8hours)

So like workaround i shutdown and close the VMware Fusion (virtualization of windows) during my lunch.

When i come back i see no problem all are fine i can launch and start again my virtual session Windows and enter in my windows session,

BUT just few seconds later PANIC of my macBook and all is freeze. Force a shutdown of my macBook and start again 😕

To conclude: Next time i will shutdown my Macbook to be sure.

And if i can suggest other users before to start a macBook upgrade wait 1 month if there's no issue.

BUT in the next version of macOS (bigSur) update would be forced 😕 can be a good thing and worse in this situation...

Hope Apple will send a little update for this issue before we must wait September for bigSur or VMware?!?

VM Ware Fusion version: Professional Version 11.5.5 (16269456)

macOS Catalina version: 10.15.6 (19G73)

[michelstoffel]

I try it change nothing crash again...

[iay]

The defect is likely to severely affect virtualization/emulation software which does not use Apple's Hypervisor.framework to do the low-level work.  The same defect could theoretically affect other non-virtualization/non-emulation software too, but I have not confirmed this possibility, and in any case it is unlikely to be anywhere near as severe as for virtualization/emulation...

For what it's worth, that does seem to be the case in that Docker Desktop for Mac (which I believe uses the framework these days) doesn't seem to be nearly as affected. It's a very different case in many other ways than Fusion, though, so that might not be significant.

If you are encountering this memory leak problem even when you are not using Fusion, there's a chance it could possibly be triggered by some other software package.

I do see a slow leak in kalloc.32 of the order of about 100MB a day, even without Fusion running. I haven't pinned it down. The only non-Apple kexts I have loaded seem to be from some audio software, a keyboard thing called Karabiner Elements and several from VirtualBox (although I'm not running it and have not since last boot, the kexts are loaded).

I realise it's off-topic for this forum, but is there any way to find out what's making these allocations?

[dariusd]

I realise it's off-topic for this forum, but is there any way to find out what's making these allocations?

I wouldn't have called that off-topic... A perfectly reasonable and relevant troubleshooting question.

The unfortunate part is that I can think of no easy way of finding the source of the allocations... Your options are the simplistic and mildly irritating option – trying to correlate the leak with some activity on your host (i.e. audio playback/recording? keyboard activity?) or temporarily uninstalling/deactivating stuff until the leak stops – or the rocket surgery option – using a kernel debugger – and the kernel debugger is not really a practical option for most people.

Random thought: If VirtualBox's kexts are loaded, perhaps it has networking services active (bridge/NAT/DHCP), and something in there might potentially be a trigger for the leak.

--

Darius

[kigoi]

so i use virtualbox, lightly, but i've learned a few things this week about this bug that might be useful.

i had been crashing after about 7 hours, but i got it down to only needing to restart once in morning & then before bed.

here are the adjustments i made to my mac setup:

• to stabilize system, turned off screen sharing & file sharing
• to free up memory, turned off wi-fi, bluetooth & optional helper apps
• cuz couldn't see how it would hurt, turned off powernap & did 'pmset -a standby 0' (as advised by someone who was having these crashes during sleep)
• to monitor system, installed 'power on time' & istat menus (configured to show memory pressure on menu bar, and to alert when pressure reaches 60%)

the last item, watching memory pressure, is very important. i don't know if 60% is a threshold for everyone, but i found as pressure approaches 65%, i can crash the computer by launching a large app.

my istat menus setup shows only the memory pressure % on the menu bar, bolded, in purple.

'power on time' is there to give me a sense of how fast the slope is in the current session.

also it looks like the first normal session after a safe boot gets sick faster? maybe triggered by rebuilding caches/indexes/etc?

ps. i have two memory pressure notifications set in istat: a banner at 54% and an alert at 57%. i've learned that the system itself sometimes has memory spikes (on wake, is the biggest) that can trigger the crash if the memory situation is already bad. so to defend against spikes, when i hit 55% i start quitting background apps, and at 58% i either restart or, if i need to keep working on something, i quit unrelated critical apps.

pps. i'm also delaying heavy guest file i/o to night hours, when other pressure on memory is low. this makes the workday much less nervous.

ppps. kinda obvious, but i also reduced the memory allocation of the virtual machine, by about 1/3, so now it's just below recommended but still smooth.

[ColoradoMarmot]

Yeah, they even pulled the installers from the terminal softwareupdate command library.  If you use installinstallmacos.py you can get a beta version of 10.15.2, but that's the only option unless the full installer is archived somewhere locally (thankfully my admin had a copy).  Older versions aren't even out on the developer site, which is *really* stupid.   Apple's gotten very user hostile with updates since catalina.

[rossco_au]

Here's a tip for anyone who wants to downgrade to 10.15.5 and doesn't have a full installer:

1.  Download MDS from twocanoes: https://twocanoes.com/products/mac/mac-deploy-stick/​

2.  Install and open MDS

3.  Use Download macOS at bottom of left pane to download 10.15.5 - Make sure you download to a subfolder under /Users/Shared - if you don't you'll get a permissions error.  No progress is reported in MDS but if you open the log viewer you'll see it downloading (Window | Show Log menu item in MDS).

4.  This will create a  sparse image in the folder you downloaded to.  Double click the sparse image in Finder to mount it

5.  Open the disk you just mounted in Finder and open the Applications Folder.

6.  Double click “Install macOS Catalina“ and install.  Crack open your favourite beverage and wait patiently for the install to complete.

I've just completed this - haven't run some VMs in anger much yet to confirm the rollback worked but macOS is reporting 10.15.5 is installed.

[xfoo]

I tried running this MDS application (in a vm running macOS 10.14), and it only offers to download 10.15.3, 10.15.4, 10.15.6 from the 10.15.x series right now. 😕

[rossco_au]

Hmm.. on my MB Pro 16" I get this:

[rossco_au]

If you're stuck you could downgrade to 10.15.4 then apply the 10.15.5 patch.

I wonder if the 10.15.5 is available for the MB Pro 16" because there was a supplemental update for 10.15.5 specifically for that model???

[xfoo]

The build number for 10.15.5 in your screenshot doesn't match what I see elsewhere (it should be 19F96 or 19F101 for the supplemental update). Thanks for the tips anyways. I did manage to dig up a 10.15.5 installer elsewhere. Might still hold out for a quick fix from Apple.

I did file a report at https://feedbackassistant.apple.com/​ because I've heard "duplicating radars" (filing duplicate bug reports that others have also filed) might count as another vote for getting things fixed.