Memory leak in ZFS?

Bartosz Stec admin at
Tue Feb 8 09:58:25 UTC 2011

W dniu 2011-02-07 22:37, Emil Muratov pisze:
>> 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)
> smb.conf
> [global]
> 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?

I'm glad someone else finally picked that problem, so there's 
appareantly no memory-eating ghost in my machine ;)
Here's my thread on stable list about this issue:

And in fact, PC reported in thread above is also SAMBA server with 
aio/sendfile enabled and ZFS.

I would be happy testing some patches if necessary, because until now I 
need to monitor memory and reboot this server before it dies.

Bartosz Stec

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