Bug 210070

+++ This bug was initially created as a clone of Bug #202971 +++

Description of problem:
modprobe blkbk/netbk fails due to memory allocation failures

Version-Release number of selected component (if applicable):
2.6.17-1.2566.fc6xen

Additional info:
FATAL: Error inserting blkbk
(/lib/modules/2.6.17-1.2566.fc6xen/kernel/drivers/xen/blkback/blkbk.ko): Cannot
allocate memory
modprobe: page allocation failure. order:8, mode:0xd0

Call Trace:
 [<a00000010001c8c0>] show_stack+0x40/0xa0
                                sp=e00000001f3ffc20 bsp=e00000001f3f9230
 [<a00000010001c950>] dump_stack+0x30/0x60
                                sp=e00000001f3ffdf0 bsp=e00000001f3f9218
 [<a0000001000fdce0>] __alloc_pages+0x500/0x540
                                sp=e00000001f3ffdf0 bsp=e00000001f3f91a0
 [<a0000001000fddd0>] __get_free_pages+0xb0/0x140
                                sp=e00000001f3ffe00 bsp=e00000001f3f9178
 [<a0000001003b35c0>] balloon_alloc_empty_page_range+0x80/0x400
                                sp=e00000001f3ffe00 bsp=e00000001f3f9130
 [<a0000002003cc190>] netback_init+0x190/0x440 [netbk]
                                sp=e00000001f3ffe30 bsp=e00000001f3f90f8
 [<a0000001000c5140>] sys_init_module+0x180/0x400
                                sp=e00000001f3ffe30 bsp=e00000001f3f9088
 [<a0000001000140e0>] ia64_ret_from_syscall+0x0/0x40
                                sp=e00000001f3ffe30 bsp=e00000001f3f9088
 [<a000000000010620>] __start_ivt_text+0xffffffff00010620/0x400
                                sp=e00000001f400000 bsp=e00000001f3f9088

Full log attached

I believe this is fixed by
http://xenbits.xensource.com/ext/xen-ia64-unstable.hg?cs=bef360142b62
I'll follow up with confirmation on that after testing.

-- Additional comment from aron on 2006-09-14 15:31 EST --
Mentioned changeset doesn't fix this problem.

There are three ways to fix this problem:
(1) link blkback and netback into xen kernel statically instead of as modules.
(2) wait for upstream xen-ia64 to finish xencomm implementation (in progress)
(3) debug the balloon driver issues that cause this problem presently

Of these, I've been working on #3 but may not have a fix soon enough.  I think
we should go ahead with #1 while we wait for #2 (which hopefully will be ready
for rhel5 release).  Statically linking the blkback and netback modules has no
negative effect on domU, but it enables us to put more effort into testing
fedora/rhel5 xen/ia64, which we can't do well right now.

-- Additional comment from aron on 2006-09-29 14:00 EST --
The xencomm implementation is nearly complete, but I misunderstood that it would
fix the problem.  It seems that the real issue is that the netbk and blkbk
drivers need to be loaded ASAP in initramfs instead of deferring them to the
xend script.

This is basically the same problem as
https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=201796 which I think was
closed prematurely.