Hi Mike, Let me explain the problem again.
Problem Statement: the timkeeping is stopped, do_timer is no more a job of cpu0. The reason: the variable "tick_do_timer_cpu" is not set to correct CPU (cpu0) And when BUG() happens, the tick_do_timer_cpu variable stay set to 1, 2 or 3 (we have 4 cores) And finally any code running on core0 (which relies on jiffies incrementing) doesn’t work because there is nobody to increment jiffies. There is tick_handover_do_timer, and if that is called then things are fine, but that is also not getting called because it is tightly coupled with hotplug. since cpu_down is not getting called, this handover is not happening. and the last status of the variable tick_do_timer_cpu is always pointing to DEAD cpu (1,2 or 3). and core0 waits forever (where if the code relies on the increment of jiffies). Regards, -Oza -----Original Message----- From: Mike Galbraith [mailto:umgwanakikb...@gmail.com] Sent: Thursday, May 07, 2015 8:53 AM To: pawandeep oza Cc: linux-kernel@vger.kernel.org; malayasen rout; Oza (Pawandeep) Oza Subject: Re: [KERNEL BUG] do_timer/tick_handover_do_timer 3.10.17 On Wed, 2015-05-06 at 22:57 +0530, pawandeep oza wrote: > but when say core0 has raised BUG.. ... > what is the right way to approach this problem Look at the spot BUG() printed? BUG() means "Way to go slick, the code you fed me (file:line) is toxic. Have a nice day, your ex-buddy core0". -Mike
