Frequent kernel panic with compat_linux module

[Nicolas Joly <njoly%pasteur.fr@localhost>]

Hi,

While testing with compat_linux module a little further, i frequently
encounter kernel panics ... They all show the same location, but in
different processes (tar, ld, gmake, ...).

kernel: page fault trap, code=0
Stopped in pid 374.1 (tar) at   compat_linux:linux_syscall+0x92:        movq
$0,0x308(%rbx)
db{0}> bt
linux_syscall() at compat_linux:linux_syscall+0x92
kernel: page fault trap, code=0
Faulted in DDB; continuing...
db{0}> show reg
ds          0x1a4
es          0xa01
fs          0x9cb0
gs          0xb8c7
rdi         0xffff80004a25cb40
rsi         0xffff80004a25ccfc
rbp         0x246
rbx         0x8
rdx         0
rcx         0x4
rax         0
r8          0xffff80004a253cf0
r9          0
r10         0x1
r11         0
r12         0xffff80004a1a6c38
r13         0xffff80004a16bb90
r14         0x2
r15         0xffff80004a16bb90
rip         0xffffffff80e36a42  linux_syscall+0x92
cs          0x8
rflags      0x10282
rsp         0xffff80004a1a6c40
ss          0x10
compat_linux:linux_syscall+0x92:        movq    $0,0x308(%rbx)

njoly@lanfeust [modules/compat_linux]> gdb ./obj.amd64/compat_linux.kmod 
GNU gdb 6.5
[...]
This GDB was configured as "x86_64--netbsd"...
(gdb) l *(linux_syscall+0x92)
0xca42 is in linux_syscall (/local/src/NetBSD/src/sys/sys/syscallvar.h:62).
57      {
58              int error;
59      
60              l->l_sysent = sy;
61              error = (*sy->sy_call)(l, uap, rval);
62              l->l_sysent = NULL;
63      
64              return error;
65      }
66      

I reliabily encounter it when i do some compilations under a Gentoo
Linux stage3 chroot. Issuing a few `make clean && make' suffice ...

I do not see the problem when the same kernel include the COMPAT_LINUX
option. And this seems to be amd64 specific as i can't reproduce it on
an i386 machine ...

This is mostly a GENERIC+DIAGNOSTIC kernel with a few extra devices,
(with or without compiled with debugging information).

Any idea ?
Thanks.

-- 
Nicolas Joly

Biological Software and Databanks.
Institut Pasteur, Paris.