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Message-ID: <123ebd58-9ca1-4a12-bdb7-c35d0c48c93c@bytedance.com>
Date: Fri, 1 Mar 2024 11:47:05 +0800
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Subject: Re: general protection fault, probably for non-canonical address in
 pick_next_task_fair()
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To: Breno Leitao <leitao@debian.org>, peterz@infradead.org, bp@alien8.de,
 tglx@linutronix.de
Cc: linux-kernel@vger.kernel.org, Chen Yu <yu.c.chen@intel.com>,
 Oliver Sang <oliver.sang@intel.com>
References: <ZeCo7STWxq+oyN2U@gmail.com>
From: Abel Wu <wuyun.abel@bytedance.com>
In-Reply-To: <ZeCo7STWxq+oyN2U@gmail.com>
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(+ Chen Yu, Oliver Sang)

On 2/29/24 11:55 PM, 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.
> 
> This is happening in upstream kernel against the following commit
> d206a76d7d2726 ("Linux 6.8-rc6")
> 
> This is the exercpt that shows before the crash:
> 
> 	general protection fault, probably for non-canonical address 0xdffffc0000000014: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC KASAN
> 	KASAN: null-ptr-deref in range [0x00000000000000a0-0x00000000000000a7]
> 
> This is the stack that is getting it
> 
> 	? __die_body (arch/x86/kernel/dumpstack.c:421)
> 	? die_addr (arch/x86/kernel/dumpstack.c:460)
> 	? exc_general_protection (arch/x86/kernel/traps.c:? arch/x86/kernel/traps.c:643)
> 	? asm_exc_general_protection (arch/x86/include/asm/idtentry.h:564)
> 	? pick_next_task_fair (kernel/sched/sched.h:1453 kernel/sched/fair.c:8435)
> 	? pick_next_task_fair (kernel/sched/fair.c:5463 kernel/sched/fair.c:8434)
> 	? update_rq_clock_task (kernel/sched/core.c:?)
> 	__schedule (kernel/sched/core.c:6022 kernel/sched/core.c:6545 kernel/sched/core.c:6691)
> 	schedule (kernel/sched/core.c:6803 kernel/sched/core.c:6817)
> 	syscall_exit_to_user_mode (kernel/entry/common.c:98 include/linux/entry-common.h:328 kernel/entry/common.c:201 kernel/entry/common.c:212)
> 	do_syscall_64 (arch/x86/entry/common.c:102)
> 	? irqentry_exit_to_user_mode (kernel/entry/common.c:228)
> 	entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:129)
> 
> Full dmesg: https://paste.mozilla.org/RiLnt4QO#
> Configs: https://paste.mozilla.org/XJ9wbdRp
>