In UP systems, the idle task is initialized using the init_task structure from which the command name is taken (currently "swapper"). In SMP systems, one idle task per CPU is forked by the worker thread from which the task structure is copied. The command name is, therefore, "kworker/0:0" or "kworker/0:1", if not updated. Since such update was lacking, all idle tasks in SMP systems were incorrectly named. This longtime bug was not discovered immediately, because there is no /proc/0 entry - the bug only becomes apparent when tracing is enabled. This patch sets the command name of the idle tasks in SMP systems to the name that is used in the INIT_TASK structure suffixed by a slash and the number of the CPU. Signed-off-by: Carsten Emde <C.Emde@xxxxxxxxx> --- include/linux/init_task.h | 3 ++- kernel/sched.c | 4 ++++ 2 files changed, 6 insertions(+), 1 deletion(-) Index: linux-3.0.7-rt20/include/linux/init_task.h =================================================================== --- linux-3.0.7-rt20.orig/include/linux/init_task.h +++ linux-3.0.7-rt20/include/linux/init_task.h @@ -132,6 +132,7 @@ extern struct cred init_cred; # define INIT_TIMER_LIST #endif +#define INIT_TASK_COMM "swapper" /* * INIT_TASK is used to set up the first task table, touch at * your own risk!. Base=0, limit=0x1fffff (=2MB) @@ -168,7 +169,7 @@ extern struct cred init_cred; .group_leader = &tsk, \ RCU_INIT_POINTER(.real_cred, &init_cred), \ RCU_INIT_POINTER(.cred, &init_cred), \ - .comm = "swapper", \ + .comm = INIT_TASK_COMM, \ .thread = INIT_THREAD, \ .fs = &init_fs, \ .files = &init_files, \ Index: linux-3.0.7-rt20/kernel/sched.c =================================================================== --- linux-3.0.7-rt20.orig/kernel/sched.c +++ linux-3.0.7-rt20/kernel/sched.c @@ -71,6 +71,7 @@ #include <linux/ctype.h> #include <linux/ftrace.h> #include <linux/slab.h> +#include <linux/init_task.h> #include <asm/tlb.h> #include <asm/irq_regs.h> @@ -6104,6 +6105,9 @@ void __cpuinit init_idle(struct task_str */ idle->sched_class = &idle_sched_class; ftrace_graph_init_idle_task(idle, cpu); +#if defined(CONFIG_SMP) + sprintf(idle->comm, "%s/%d", INIT_TASK_COMM, cpu); +#endif } /* -- To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
