I'm trying to do a btrfs send of my main system volume. This volume is huge, containing a bunch of full filesystem trees (backups and special chroots). Everything seems to start out ok, but somewhere halfway, the send side of the transfer dies with: ERROR: send ioctl failed with -12: Cannot allocate memory Leading to receive-sided ERROR: unexpected EOF in stream. This happens consistently with this volume. There is plenty of memory available and this is not some OOM-kill situation, so I guess there is some imposed memory limit somewhere.
Are there messages in syslog saying something about the failed allocation?
I've changed disks since I filed this report and used rsync to move everything. I haven't seen this error since then. Probably something got corrupted, I had the previous disk/volume for a long time and with different mount options over time, so I guess something got corrupted. For now, I will close this issue, will reopen if it pops up again. Of course with a bit more info than now if I can find it :)