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)

[rossco_au]

19F2200 is specifically for the MB Pro 16" 9600M:

https://mrmacintosh.com/new-amd-5600m-16-mbpro-10-15-5-supplemental-update-forked-build/

Apologies if it doesn't work for others... I was trying to help 🙂

But at least you can downgrade to 10.15.4 then back up to 10.15.5 which is better than nothing.

[dempson]

You can't use this method to downgrade to 10.15.3 or 10.15.4 either, unless you have the right Mac model. Of the listed versions, 10.15.3 (19D2064) was the release system for the 2020 13-inch MacBook Air; 10.15.4 (19E2269) is probably for the 2020 13-inch MacBook Pro (according to MacTracker they were released with 19E2265 so this is likely to be a post-release minor fix). In general, if you see a four digit build number after the letter, then it is usually a model-specific installer. The general release has smaller numbers (10.15.3, 10.15.4 and 10.15.5 are 19D76, 19E266, and 19F96 or 19F101 respectively).

My 16-inch MacBook Pro (from late 2019) can't download 10.15.3, 10.15.4 or 10.15.5 using this method ("Install failed with error: Update not found"), but it can re-download 10.15.6.

For Macs introduced in 2019 or earlier, you can't download a 10.15.0 through 10.15.5 installer any more. To install 10.15.5 you would have needed to get the Catalina installer before 10.15.6 was released, and kept a copy of it (or moved it out of Applications) before proceeding with the install. If you downloaded Catalina but left installation for a few days, check your Time Machine backups - you might still have a copy sitting in an older version of the Applications folder.

I kept most of my older installers, so I can roll back to 10.15.5 if I decide it is worth the trouble. For now I've managed to dodge the problem by not using VMware Fusion on that computer - I can run it on another Mac which is still on Mojave.

Also worth noting that you don't need a third party utility to download the full installer. Catalina's sofwareupdate command line tool can download the available versions (which support your model) with something like this:

softwareupdate --fetch-full-installer --full-installer-version 10.15.6

This was a new feature for the softwareupdate tool in macOS Catalina so it won't work if you are running Mojave or earlier, but it can download the 10.13.6 and 10.14.6 installers (if your Mac is old enough to run them). These options aren't in the man page but are in the help (softwareupdate --help). If you just want the latest installer, you only need the first option.

[xfoo]

So I ended up running the macOS 10.15.5 full installer (and then the 10.15.5 supplemental update afterwards) on top of my macOS 10.15.6 installation.

With just some quick testing, "sudo zprint -d" is now quiet when running a windows VM in VMWare Fusion. No more crazy "kalloc.32" leaks observed any more.

[ColoradoMarmot]

This is exactly what I found - it's just a front end for the softwareupdate tool, and Apple's pulled the installers for older machines.

[rossco_au]

What a mess.  Thank you Apple (not).

I started with softwareupdate trying to fetch 10.15.5 and it downloaded something but failed after downloading.

Shift-Option-Command-R reinstalled 10.15.6 - not the original version that came on my MBPro

MDS worked - but as you suggest it looks like it will only work in some cases.

[Alex_Ma]

I just observed how this happens. Previously my Mac crashed while asleep. This time I noticed something strange - I saw a dialog window asking for keychain credentials on behalf of various macOS services. Sometimes I was able to switch between application windows, but they did not accept any input. OS honestly tried to fix this - some system applications randomly restarted from time to time, I saw desktop going black and then showing wallpaper again. This looked like complete madness. I had to long press power button to make it restart. So yeah, the kernel goes crazy. I do not think it's a memory leak, I think some part of the kernel becomes corrupted.

[dariusd]

Everything you describe there is what I would expect to see from an OS suffering from resource starvation, which will trigger a lot of failures and program terminations, and will activate a lot of error-recovery and resilience routines which do not otherwise need to ever do any work.

Kernel memory corruption is much more likely to trigger a rapid kernel panic (from a page fault, a general protection fault, or an invalid opcode exception) than cause applications to misbehave for a period of time like you describe.

[ColoradoMarmot]

And based on your analysis, it's *clearly* a memory leak.  Kernel's running out of that is just as bad as an engine running out of oil...smoke, grinding, and finally the whole thing seizes up.

[savda]

I have a 2017 Macbook Pro and 10.15.5 appeared in the list for me with the same build number.

It installed fine and reverted me correctly as far as I can tell (issue has also disappeared - was impacting me several times a day with a Win10 VM).

I had a backup image if it all went wrong.

Thanks very much @rossco_au and dariusd​ for your help in this thread.

A very frustrating issue.

Dave.

[rossco_au]

Glad it helped you @savda - made me feel like it was worth the effort now . Interesting that the same build appeared for your '17 Macbook Pro - seems a bit random what works and what doesn't. :smileysilly:

[Alex_Ma]

Back when I had 16Gb MacBook Pro, I often hit memory limit and did not observe anything strange. Mac started to become sluggish, I received a message that system is low on memory, but as soon as I closed some application that consumed a lot of memory, it would get back to normal. Now it is different.

[xfoo]

Usually when applications exhaust all RAM, the OS would just start swapping to disk and everything is fine (but slows down).

I think what happens here is the memory leak exhausts a particular allocation zone in the kernel, which perhaps has a different (lower) limit compared to regular memory allocations made by applications, and as you can see with "log show --start 2020-08-01 12:00:00" (put in a timestamp just before things start going south) the kernel starts killing pretty much every critical system daemon process - and then perhaps immediately restarts some of these (since they are critical and should always be running). But then these processes fail to run/reinitialize properly, probably because the kernel is unable to service them properly due to the exhaustion of a particular kernel memory zone. So things ends up in a zombie state where everything from the GUI to authentication subsystems are unable to talk to each other, things time out, act weird, act like there are no saved credentials, starts beachballing, and so on.

This is just my rather uneducated guess, based on what the logs show.

Edit: In other words:

* When user-mode applications exhaust memory, the kernel can swap that stuff out to disk and make a small note in kernel memory about where to find it later. Things run OK but slow.

* When the kernel exhausts memory, it cannot be swapped out (you can't put the note about where things are on disk, on disk), so it has no other choice but to try to start killing processes in the hope of triggering release of kernel memory as a side effect. But since it's the kernel itself that is leaking, killing processes doesn't help much, and makes things a hundred times worse since critical subsystems are no longer functional. You can find some of the logged error messsages in Apple's open source files for their kernel, perhaps in kern_memorystatus.c

[wila]

Hi,

There's a big difference between applications using up all the freely available memory and having a memory leak.

This is a bit simplified, but the general idea is this:

If an application uses up the freely available memory then you can get your RAM back by closing the application.

However if you have a memory leak, closing the application will not reclaim the memory that was leaked, because the memory that was leaked does not belong to that application.

As far as the kernel concern it is still in use and cannot be freed.

This is why it doesn't always help to close applications and why it is such a big problem that only a reboot can resolve.

--
Wil

[Jadraker]

Hi, you're my hero. Thanks to you I'm back with Catalina 10.15.5. I've a MBP 15' 2018 and I downloaded the image 19F2200 that corresponds to 10.15.5.

I can now patiently wait for 10.15.7 hoping it'll fix this annoying (to say the least) bug.

[Alex_Ma]

Will it keep my data or I need to install it from backup?

[rossco_au]

It will downgrade in place (keeping apps, data).  But make sure you have a backup to be safe.

[Alex_Ma]

Right. In an application all this memory is allocated by the OS and when a process is terminated one way or the other, it will be released by the OS. But if the leak is in the OS, then nobody can check this. Pretty bad... Why don't they simply take Linux kernel? It would make things so much easier in so many ways.

[ColoradoMarmot]

They already have a UNIX kernel, and Linux has plenty of issues itself.

What they really need to do is invest some of that $193B in cash into QA teams - this kind of defect should have been caught in regression testing.

[Alex_Ma]

Really? I thought Linux Kernel is being monitored pretty well. By nature of being open source, it is much less likely to catch a bug like this. And if it does, it will be fixed quicker.

The fact that macOS is also a Unix version, in fact it is BSD Unix for large part, will make the transition easier. I know that Apple actually open sourced it's kernel, but there is a catch - they never open source current code, only up to a version before. Also I think they do not accept submissions. I am really pissed off at how they handled Nvidia compatibility. I had to build a dedicated server for ML computations simply because third party drivers do not work on macOS, while even Windows running on the same MacBook works with Nvidia in an external eGPU.

[patx9309]

Hi,

Using MDS to downgrade Catalina from 10.15.6 to 10.15.5, does it like re-installing everything from scratch?

I have currently installed some applications and important data that I don't want to re-install them.

From your downgrade instructions, I just need to use MDS to download 10.15.5 and click the "Install macOS Catalina" and install it over the existing APFS volume.

Is that what I need to do?

Is there any big impact after downgrade? e.g. Key Chains, credentials, icloud etc.

I am currently running VMware fusion on Mac mini 2018 with 64G RAM, and am suffering from KPs every day.

Hope this MDS downgrade helps.

Thank you