Re: [BUG] 2.6.25-rc2-mm1 - kernel oops while bootup on s390x

[Heiko Carstens <heiko.carstens@de.ibm.com>]

On Sun, Feb 17, 2008 at 09:10:46AM +0530, Kamalesh Babulal wrote:
> To conform the patches causing the panic, I tested the 2.6.24.2 kernel with the futex-fix-init-order.patch and
> futex-runtime-enable-pi-and-robust-functionality.patch applied and they seem to cause the kernel
> panic.
> 
> Unable to handle kernel pointer dereference at virtual kernel address 0000000000
> 000000
> Oops: 0004 #1¨ SMP
> Modules linked in:
> CPU: 0 Not tainted 2.6.25-rc2-mm1-autotest #1
> Process swapper (pid: 1, task: 000000003f830000, ksp: 000000003f83ba48)
> Krnl PSW : 0704a00180000000 000000000024b2be (futex_atomic_cmpxchg_std+0x12/0x28
> )
>            R:0 T:1 IO:1 EX:1 Key:0 M:1 W:0 P:0 AS:2 CC:2 PM:0 EA:3
> Krnl GPRS: 0000000000000074 00000000fffffff2 0000000000000000 0000000000000000
>            0000000000000000 0000000000000001 0000000000000000 00000000004d0764
>            0000000000000000 00000000004d8768 0000000000000000 000000003f83bdb0
>            0000000000000040 0000000000343950 00000000000627e4 000000003f83bdb0
> Krnl Code: 000000000024b2b2: b90400bf           lgr     %r11,%r15
>            000000000024b2b6: a718fff2           lhi     %r1,-14
>            000000000024b2ba: b2790100           sacf    256
>           >000000000024b2be: ba342000           cs      %r3,%r4,0(%r2)
>            000000000024b2c2: 1813               lr      %r1,%r3
>            000000000024b2c4: b2790000           sacf    0
>            000000000024b2c8: b9140021           lgfr    %r2,%r1
>            000000000024b2cc: e3b0b0700004       lg      %r11,112(%r11)
> Call Trace:
> (<000000003f83bda8>¨ 0x3f83bda8)
>  <00000000004bdeec>¨ init+0x30/0x104
>  <00000000004b0c40>¨ kernel_init+0x1e0/0x370
>  <000000000001a5c6>¨ kernel_thread_starter+0x6/0xc
>  <000000000001a5c0>¨ kernel_thread_starter+0x0/0xc
> 
>  <4>--- end trace 561bb236c800851f ¨---
> note: swapper1¨ exited with preempt_count 1
> Kernel panic - not syncing: Attempted to kill init!

Thanks for reporting! Patch below should fix it.

Index: linux-2.6/arch/s390/lib/uaccess_std.c
===================================================================
--- linux-2.6.orig/arch/s390/lib/uaccess_std.c
+++ linux-2.6/arch/s390/lib/uaccess_std.c
@@ -293,8 +293,8 @@ int futex_atomic_cmpxchg_std(int __user 
 
 	asm volatile(
 		"   sacf 256\n"
-		"   cs   %1,%4,0(%5)\n"
-		"0: lr   %0,%1\n"
+		"0: cs   %1,%4,0(%5)\n"
+		"   lr   %0,%1\n"
 		"1: sacf 0\n"
 		EX_TABLE(0b,1b)
 		: "=d" (ret), "+d" (oldval), "=m" (*uaddr)