On Thu, 12 Apr 2012 19:30:08 -0400 Richard Yao <r...@cs.stonybrook.edu> wrote:
> I am running Gentoo on ZFS using the kernel modules from sys-kernel/spl > and sys-fs/zfs. If I put swap on ZFS, the kernel appears to deadlock > when it tries to use it. I am having trouble getting a backtrace. > > Does anyone have any suggestions on how I could debug this? > If it's that easy to reproduce, I'd suggest to try it in usermode linux (ARCH=um make). It's a linux kernel as unprivileged userspace process. Easy to attach with gdb, add printk and etc. Does not support SMP. - swap on FS has some optimizations which are not very well suited to copy-on-write files. kernel picks file block map from filesystem and tries to use it directly (code might be shared with FIBMAP implementation). It's a tricky part to handle. - triple-check all ZFS memory allocations go at least via GFP_NOFS allocations. -- Sergei
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