Prev: 2.6.34-rc7: hctosys.c: unable to open rtc device (rtc0)
Next: 2% LOAN OFFER
From: Serge E. Hallyn on 11 May 2010 05:00
Quoting Oleg Nesterov (oleg(a)redhat.com):
> copy_process(pid => &init_struct_pid) doesn't do attach_pid/etc.
>
> It shouldn't, but this means that the idle threads run with the wrong
> pids copied from the caller's task_struct. In x86 case the caller is
> either kernel_init() thread or keventd.
>
> In particular, this means that after the series of cpu_up/cpu_down an
> idle thread (which never exits) can run with .pid pointing to nowhere.
>
> Change fork_idle() to initialize idle->pids[] correctly. We only set
> .pid = &init_struct_pid but do not add .node to list, INIT_TASK() does
> the same for the boot-cpu idle thread (swapper).
>
> Signed-off-by: Oleg Nesterov <oleg(a)redhat.com>

Acked-by: Serge E. Hallyn <serue(a)us.ibm.com>

> ---
>
> kernel/fork.c | 14 +++++++++++++-
> 1 file changed, 13 insertions(+), 1 deletion(-)
>
> --- 34-rc1/kernel/fork.c~3_FORK_IDLE_SET_PIDS 2010-03-24 18:07:03.000000000 +0100
> +++ 34-rc1/kernel/fork.c 2010-05-10 20:45:33.000000000 +0200
> @@ -1339,6 +1339,16 @@ noinline struct pt_regs * __cpuinit __at
> return regs;
> }
>
> +static inline void init_idle_pids(struct pid_link *links)
> +{
> + enum pid_type type;
> +
> + for (type = PIDTYPE_PID; type < PIDTYPE_MAX; ++type) {
> + INIT_HLIST_NODE(&links[type].node); /* not really needed */
> + links[type].pid = &init_struct_pid;
> + }
> +}
> +
> struct task_struct * __cpuinit fork_idle(int cpu)
> {
> struct task_struct *task;
> @@ -1346,8 +1356,10 @@ struct task_struct * __cpuinit fork_idle
>
> task = copy_process(CLONE_VM, 0, idle_regs(&regs), 0, NULL,
> &init_struct_pid, 0);
> - if (!IS_ERR(task))
> + if (!IS_ERR(task)) {
> + init_idle_pids(task->pids);
> init_idle(task, cpu);
> + }
>
> return task;
> }
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo(a)vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
 | 
Pages: 1
Prev: 2.6.34-rc7: hctosys.c: unable to open rtc device (rtc0)
Next: 2% LOAN OFFER