Memory leak in ZFS?

Emil Muratov gpm at
Mon Feb 7 21:56:39 UTC 2011

> For the past few weeks, I noticed that the amount of memory reported in  
> top
> (sum of active, inact, wired, cache buf and free) keeps decreasing as the
> uptime increases. I can't pinpoint to when I first noticed this, as I  
> have
> updated the system a few times just in case this has been fixed.

Yes, I have the same issue on my home file storage. My system is 8.1  
amd64, 2G ram, zfs on root raidz with 4x1,5T drives.
After updating to stable a couple of days ago I noticed that the system  
leaks memory very fast. Checking here and there I found that the issue  
concerns sendfile (yep, again!).

How to reproduce:
Configure samba with aio and sendfile (mine is version 3.5.6)

use sendfile=true
aio read size = 16384

Download a couple of large samba shared files (8-10 gigs).

While downloading files I can see that memory decreazes to nowhere  
very-very fast, several MBs per second! First it drains free mem, than  
active and inactive, than comes wired until the whole system commits  
suicide suffocating itself to the death.
The only way to free memory is to reboot the system. I can't unload zfs  
module like PJD suggested to do, 'cause my root is on zfs :(
I'll try to make a bootable flash and move root to the flash to try to  
unload module and what will happen.

Everything was OK in stable before the new year, sendfile used to pump  
free and wired memory to inactive than slowly reclaiming it back. But it  
seems something was changed after NY holydays?

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