Big Sur, Time Machine, SMB, umount, and Safari networking issue

Just sampled the `umount` process when it was spinning and it’s basically blocked on `unmount` in `libsystem_kernel.dylib` which is simply the `unmount` syscall (thus whatever blocks is doing so in the kernel). I believe that the syscall is marked as non-interruptible which might explain why `kill -9` and friends don’t work. This could happen at the VFS layer but much more likely in the smbfs kext/driver.

I believe there were some changes in this kext for Big Sur (since they’ve also finally removed AFP) so I wouldn’t be surprised if some bug slipped in the first release (there were a bunch of `smbfs.kext` bugs already discovered during the betas too).

The wireless backup worked for me at first but then it stopped. I removed the back up volume and now I am unable to add it back. It simply does not show in Time Machine even though it is properly mounted. Any ideas? See screenshot...

I have been having the same problem since upgrading to Big Sur (minus the Safari networking problem, although I have had intermittent connections issues in Safari and come to think of it, it might actually be that same issue). I don’t even have to let Time Machine mount and unmount the volume, simply doing so from Finder will lead to `umount` (seemingly) spinning on a CPU core for a few minutes and no amount of `kill -9` will actually kill it, as you’ve stated.

I’ve had other issues with SMB since upgrading to Big Sur too, for example AutoMounter (https://www.pixeleyes.co.nz/automounter/) complains that SMB is not available and won’t mount the network shares, although I have no idea if it’s even related but coincidentally started with Bug Sur.

I failed to mention that it stopped working right after updating the firmware of the RT2600ac

to 1.2.4-8081 Update 1. It worked before. What is interesting is that this firmware did not just come out now but on Sept 24. I just did not see the update before. Hoping that Synology will soon publish a new firmware update with a fix for Big Sur.

I've had this exactly issue.(MacBook Pro mid 2015 15inch with Synology NAS TimeMachine via afp)

"umount" process eats 99% CPU. If you want to kill this process, you'll find "Force quit" or "kill -9" does not work.

Meanwhile Safari can not open any web pages but Chrome and Firefox are OK.

Then you want to reboot to get a fresh start...A cursor stuck spinning, can not power off properly.

I have to press the power button several seconds to do a force restart, then everything is ok again.

Next backup? ---> boom again.

I am having the same issue with umount process hanging for about 5 minutes on a 16" MacBook Pro after each TM backup except I am backing up to a WD PR4100 NAS. The process consumes 100% CPU. Safari is unusable for that 5 minutes. Hope Apple fixes this in the next Big Sur update.

Almost same issue here, but from mac mini time machine share over smb. Affected are safari and chrome (not even loading start page), diskutility (won’t open), time machine config panel (open to select new time machine target hangs). All hanging with ‘unmount’ process eating one processor completely. In my case 30 minutes before return to ‘normal’ / timeout of process

I'm experiencing this same problem. I tried to upgrade to the 11.1 beta (big sur developer beta) and the problem, unfortunately, got worse. Instead of just hanging network calls for a few apps or take up CPU cycles, the entire computer becomes unusable. All devices (bluetooth or USB) are unresponsive and I'm forced to restart the computer for it to come back.

This thread NEEDS to get more Apple Support attention. I have to pick between no more TimeMachine backups and downgrading my computer.

Umount takes 100% of cpu load and the machines slowly dies sometimes. Cursor is getting choppy and even a resatrt will not work, needs a hard shutdown on my Mac Book Pro 15" (2018). Sometimes just waiting solves the thing but it takes 10 or more minutes in which other tasks become very slow. Safari is also affected durin this time (in the first place I thought its the internet providers fault, but all other devices are conneting just fine).

Any news on this one besides turning of time machine?

I am having the same issues with my 2017 15" MBP connecting to SMB on my QNAP NAS, so I don't think it's Synology. Running Big Sur 11.1. My iMac Pro and iMac both work fine. Just the MBP.

I've turned off automatic backups for now, hopefully this is something that gets solved. For me, randomly the machine would lock up. Jittery and eventually locked cursor and need to hold power button for 10s to restart the machine. Everything else is dead.

Same problem here. Plus to sampling the umount process I also looked at dmesg. No debug info ever. Apple must have broken something in the kernel, but I think the Big Sur kernel is still not released so the only hope is Apple seeing this thread...

I'm also facing this issue on a MacBook Pro (15-inch, 2016) when backing up to an AFP-share on my NAS.

I was hoping that the upgrade to macOS 11.1 would fix it, but (as mentioned by others) It's still not working.

Exact same Problems (Timemachine, Freezing Network/ Unmount/ Safari/ Chrome!! SMB)

MacBook Pro (16 Zoll, 2019) Big Sur 11.1

I really new i should have wait. I always wait at about 6 months with new Updates.

Apple is so expensive and makes us to beta testers, really bad. Same story since ever....

We have a few Machines here (Minis, Macbook Pros, etc.).... Same Problems