Re: [BUG 2.6.20-rc2-mm1] init segfaults when CONFIG_PROFILE_LIKELY=y

On Sun, 31 Dec 2006 11:45:09 -0800 Daniel Walker wrote:

On Sun, 2006-12-31 at 23:04 +0800, Fengguang Wu wrote:
Hi,

The following messages keeps popping up when CONFIG_PROFILE_LIKELY=y:

init[1]: segfault at ffffffff8118c110 rip ffffffff8118c110 rsp 00007fff9a9d14d8 error 15
init[1]: segfault at ffffffff8118c110 rip ffffffff8118c110 rsp 00007fff9a9d14d8 error 15
init[1]: segfault at ffffffff8118c110 rip ffffffff8118c110 rsp 00007fff9a9d14d8 error 15
init[1]: segfault at ffffffff8118c110 rip ffffffff8118c110 rsp 00007fff9a9d14d8 error 15
init[1]: segfault at ffffffff8118c110 rip ffffffff8118c110 rsp 00007fff9a9d14d8 error 15
init[1]: segfault at ffffffff8118c110 rip ffffffff8118c110 rsp 00007fff9a9d14d8 error 15
init[1]: segfault at ffffffff8118c110 rip ffffffff8118c110 rsp 00007fff9a9d14d8 error 15
init[1]: segfault at ffffffff8118c110 rip ffffffff8118c110 rsp 00007fff9a9d14d8 error 15



Does this seem like an appropriate solution? This just reconstitutes
Ingo's patch by removing the unlikely calls that got added recently.

How does this fix the problem? (if it does)
What is the real cause of the problem?

Maybe a comment into vsyscall.c that says to stay away from all macro's
and possible debug code that could be added might be helpful ?

Why?

Signed-Off-By: Daniel Walker <dwalker@xxxxxxxxxx>

---
arch/x86_64/kernel/vsyscall.c | 4 ++--
1 files changed, 2 insertions(+), 2 deletions(-)

Index: linux-2.6.19/arch/x86_64/kernel/vsyscall.c
===================================================================
--- linux-2.6.19.orig/arch/x86_64/kernel/vsyscall.c
+++ linux-2.6.19/arch/x86_64/kernel/vsyscall.c
@@ -111,7 +111,7 @@ static __always_inline void do_vgettimeo
seq = read_seqbegin(&__vsyscall_gtod_data.lock);

vread = __vsyscall_gtod_data.clock.vread;
- if (unlikely(!__vsyscall_gtod_data.sysctl_enabled || !vread)) {
+ if (!__vsyscall_gtod_data.sysctl_enabled || !vread) {
gettimeofday(tv,0);
return;
}
@@ -151,7 +151,7 @@ int __vsyscall(0) vgettimeofday(struct t
* unlikely */
time_t __vsyscall(1) vtime(time_t *t)
{
- if (unlikely(!__vsyscall_gtod_data.sysctl_enabled))
+ if (!__vsyscall_gtod_data.sysctl_enabled)
return time_syscall(t);
else if (t)
*t = __vsyscall_gtod_data.wall_time_tv.tv_sec;


---
~Randy
-
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