Re: 2.6.24-rc6-mm1

[Ingo Molnar]

* Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> wrote:

> Still.  The crash is 100% repeatable and is the same every time.  
> Happens on both my i386 test boxes.
> 
> http://userweb.kernel.org/~akpm/config-sony.txt
> http://userweb.kernel.org/~akpm/config-vmm.txt
> 
> and I bisected it down to e3c1b141.

ok, can reproduce it - the patch below fixes it for me.

	Ingo

------------------------->
Subject: x86: fix system gate related crash
From: Ingo Molnar <mingo@xxxxxxx>

on 32-bit, system gates are traps.

on 64-bit, they are interrupts (which disable hardirqs).

Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
---
 include/asm-x86/desc.h |    4 ++++
 1 file changed, 4 insertions(+)

Index: linux-x86.q/include/asm-x86/desc.h
===================================================================
--- linux-x86.q.orig/include/asm-x86/desc.h
+++ linux-x86.q/include/asm-x86/desc.h
@@ -310,7 +310,11 @@ static inline void set_trap_gate(unsigne
 static inline void set_system_gate(unsigned int n, void *addr)
 {
 	BUG_ON((unsigned)n > 0xFF);
+#ifdef CONFIG_X86_32
+	_set_gate(n, GATE_TRAP, addr, 0x3, 0, __KERNEL_CS);
+#else
 	_set_gate(n, GATE_INTERRUPT, addr, 0x3, 0, __KERNEL_CS);
+#endif
 }
 
 static inline void set_task_gate(unsigned int n, unsigned int gdt_entry)
--
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