Messages in this thread | | | Date | Tue, 11 May 2010 03:54:10 -0500 | From | "Serge E. Hallyn" <> | Subject | Re: [PATCH 3/4] pids: fix fork_idle() to setup ->pids correctly |
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Quoting Oleg Nesterov (oleg@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@redhat.com>
Acked-by: Serge E. Hallyn <serue@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(®s), 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; > }
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