From mboxrd@z Thu Jan 1 00:00:00 1970 From: tglx@linutronix.de (Thomas Gleixner) Date: Tue, 22 Sep 2015 12:59:00 +0200 (CEST) Subject: [PATCH v3] arm: Fix backtrace generation when IPI is masked In-Reply-To: <1442328005-13661-1-git-send-email-daniel.thompson@linaro.org> References: <1442222294-2756-1-git-send-email-daniel.thompson@linaro.org> <1442328005-13661-1-git-send-email-daniel.thompson@linaro.org> Message-ID: To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Tue, 15 Sep 2015, Daniel Thompson wrote: > Currently on ARM when is triggered from an interrupt handler > (e.g. a SysRq issued using UART or kbd) the main CPU will wedge for ten > seconds with interrupts masked before issuing a backtrace for every CPU > except itself. > > The new backtrace code introduced by commit 96f0e00378d4 ("ARM: add > basic support for on-demand backtrace of other CPUs") does not work > correctly when run from an interrupt handler because IPI_CPU_BACKTRACE > is used to generate the backtrace on all CPUs but cannot preempt the > current calling context. > > This can be fixed by detecting that the calling context cannot be > preempted and issuing the backtrace directly in this case. Issuing > directly leaves us without any pt_regs to pass to nmi_cpu_backtrace() > so we also modify the generic code to call dump_stack() when its > argument is NULL. > > Signed-off-by: Daniel Thompson For the genric part. Acked-by: Thomas Gleixner