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authorOleg Nesterov <oleg@redhat.com>2010-05-26 14:44:11 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2010-05-27 09:12:52 -0700
commitf106eee10038c2ee5b6056aaf3f6d5229be6dcdd (patch)
treede7ce930b7119a1be00f3c7604065896d31abc9c /kernel/fork.c
parentf20011457f41c11edb5ea5038ad0c8ea9f392023 (diff)
pids: fix fork_idle() to setup ->pids correctly
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> Cc: Cedric Le Goater <clg@fr.ibm.com> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: Eric Biederman <ebiederm@xmission.com> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Mathias Krause <Mathias.Krause@secunet.com> Acked-by: Roland McGrath <roland@redhat.com> Acked-by: Serge Hallyn <serue@us.ibm.com> Cc: Sukadev Bhattiprolu <sukadev@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel/fork.c')
-rw-r--r--kernel/fork.c14
1 files changed, 13 insertions, 1 deletions
diff --git a/kernel/fork.c b/kernel/fork.c
index d32410bd4be7..bf9fef6d1bfe 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1338,6 +1338,16 @@ noinline struct pt_regs * __cpuinit __attribute__((weak)) idle_regs(struct pt_re
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;
@@ -1345,8 +1355,10 @@ struct task_struct * __cpuinit fork_idle(int cpu)
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;
}