The patch titled
pids: fix fork_idle() to setup ->pids correctly
has been added to the -mm tree. Its filename is
pids-fix-fork_idle-to-setup-pids-correctly.patch
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Subject: pids: fix fork_idle() to setup ->pids correctly
From: Oleg Nesterov <oleg@xxxxxxxxxx>
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@xxxxxxxxxx>
Cc: Cedric Le Goater <clg@xxxxxxxxxx>
Cc: Dave Hansen <haveblue@xxxxxxxxxx>
Cc: Eric Biederman <ebiederm@xxxxxxxxxxxx>
Cc: Herbert Poetzl <herbert@xxxxxxxxxxxx>
Cc: Mathias Krause <Mathias.Krause@xxxxxxxxxxx>
Cc: Roland McGrath <roland@xxxxxxxxxx>
Cc: Serge Hallyn <serue@xxxxxxxxxx>
Cc: Sukadev Bhattiprolu <sukadev@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/fork.c | 14 +++++++++++++-
1 file changed, 13 insertions(+), 1 deletion(-)
diff -puN kernel/fork.c~pids-fix-fork_idle-to-setup-pids-correctly kernel/fork.c
--- a/kernel/fork.c~pids-fix-fork_idle-to-setup-pids-correctly
+++ a/kernel/fork.c
@@ -1340,6 +1340,16 @@ 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;
@@ -1347,8 +1357,10 @@ 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;
}
_
Patches currently in -mm which might be from oleg@xxxxxxxxxx are
linux-next.patch
cpu-timers-optimize-run_posix_cpu_timers.patch
oom-select_bad_process-check-pf_kthread-instead-of-mm-to-skip-kthreads.patch
oom-select_bad_process-pf_exiting-check-should-take-mm-into-account.patch
oom-introduce-find_lock_task_mm-to-fix-mm-false-positives.patch
oom-oom_forkbomb_penalty-move-thread_group_cputime-out-of-task_lock.patch
oom-hold-tasklist_lock-when-dumping-tasks.patch
oom-give-current-access-to-memory-reserves-if-it-has-been-killed.patch
oom-avoid-sending-exiting-tasks-a-sigkill.patch
oom-clean-up-oom_kill_task.patch
oom-clean-up-oom_badness.patch
oom-select_bad_process-never-choose-tasks-with-badness-==-0.patch
kmod-add-init-function-to-usermodehelper.patch
exec-replace-call_usermodehelper_pipe-with-use-of-umh-init-function-and-resolve-limit.patch
umh-creds-convert-call_usermodehelper_keys-to-use-subprocess_info-init.patch
umh-creds-kill-subprocess_info-cred-logic.patch
call_usermodehelper-no-need-to-unblock-signals.patch
wait_for_helper-sigchld-from-user-space-can-lead-to-use-after-free.patch
call_usermodehelper-simplify-fix-umh_no_wait-case.patch
call_usermodehelper-umh_wait_exec-ignores-kernel_thread-failure.patch
coredump-factor-out-the-not-ispipe-file-checks.patch
coredump-cleanup-ispipe-code.patch
coredump-factor-out-put_cred-calls.patch
coredump-shift-down_writemmap_sem-into-coredump_wait.patch
exit-exit_notify-can-trust-signal-notify_count-0.patch
exit-change-zap_other_threads-to-count-sub-threads.patch
exit-avoid-sig-count-in-de_thread-__exit_signal-synchronization.patch
exit-avoid-sig-count-in-__exit_signal-to-detect-the-group-dead-case.patch
posix-cpu-timers-avoid-task-signal-=-null-checks.patch
ia64-ptrace_attach_sync_user_rbs-avoid-task-signal-=-null-checks.patch
fork-exit-move-tty_kref_put-outside-of-__cleanup_signal.patch
signals-make-task_struct-signal-immutable-refcountable.patch
signals-clear-signal-tty-when-the-last-thread-exits.patch
signals-clear-signal-tty-when-the-last-thread-exits-fix.patch
signals-kill-the-awful-task_rq_unlock_wait-hack.patch
exit-__exit_signal-use-thread_group_leader-consistently.patch
kill-the-obsolete-thread_group_cputime_free-and-taskstats_tgid_init-helpers.patch
exit-move-taskstats_tgid_free-from-__exit_signal-to-free_signal_struct.patch
check_unshare_flags-kill-the-bogus-clone_sighand-sig-count-check.patch
proc-get_nr_threads-doesnt-need-siglock-any-longer.patch
proc_sched_show_task-use-get_nr_threads.patch
keyctl_session_to_parent-use-thread_group_empty-to-check-singlethreadness.patch
proc-turn-signal_struct-count-into-int-nr_threads.patch
proc-turn-signal_struct-count-into-int-nr_threads-checkpatch-fixes.patch
proc-cleanup-remove-unused-assignments.patch
init_task-should-initialize-thread_group-list.patch
pids-init_struct_pidtasks-should-never-see-the-swapper-process.patch
pids-fix-fork_idle-to-setup-pids-correctly.patch
init_sighand-use-sig_dfl-instead-of-null.patch
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