linux-kernel - Re: general protection fault, probably for non-canonical address in pick_next_task

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Message-ID: <87msri7u8t.ffs@tglx>
Date: Thu, 29 Feb 2024 23:58:42 +0100
From: Thomas Gleixner <tglx@...utronix.de>
To: Breno Leitao <leitao@...ian.org>, peterz@...radead.org, bp@...en8.de
Cc: linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...nel.org>, Vincent
 Guittot <vincent.guittot@...aro.org>, Dietmar Eggemann
 <dietmar.eggemann@....com>
Subject: Re: general protection fault, probably for non-canonical address in
 pick_next_task_fair()

On Thu, Feb 29 2024 at 07:55, Breno Leitao wrote:
> I've been running some stress test using stress-ng with a kernel with some
> debug options enabled, such as KASAN and friends (See the config below).
>
> I saw it in rc4 and the decode instructions are a bit off (as it is here
> also - search for mavabs in dmesg below and you will find something as `(bad)`,
> so I though it was a machine issue. But now I see it again, and I am sharing
> for awareness.

The (bad) is after the faulting instruction, but gives an hint:

  2e:	0f 84 67 ff ff ff    	je     0xffffffffffffff9b
  34:	48 89 ef             	mov    %rbp,%rdi
  37:	e8 cf 70 76 00       	call   0x76710b
  3c:	e9                   	.byte 0xe9

That's an invalid opcode, which means that memory is corrupted.

Thanks,

        tglx