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[2a03:2880:30ff:1::face:b00c]) by smtp.gmail.com with ESMTPSA id q13-20020a5d61cd000000b0033e11ff6284sm1525506wrv.12.2024.02.29.07.55.26 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 29 Feb 2024 07:55:27 -0800 (PST) Date: Thu, 29 Feb 2024 07:55:25 -0800 From: Breno Leitao To: peterz@infradead.org, bp@alien8.de, tglx@linutronix.de Cc: linux-kernel@vger.kernel.org Subject: general protection fault, probably for non-canonical address in pick_next_task_fair() Message-ID: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline 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