The patch titled
introduce PF_KTHREAD flag
has been added to the -mm tree. Its filename is
introduce-pf_kthread-flag.patch
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The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
------------------------------------------------------
Subject: introduce PF_KTHREAD flag
From: Oleg Nesterov <oleg@xxxxxxxxxx>
Introduce the new PF_KTHREAD flag to mark the kernel threads. It is set
by INIT_TASK() and copied to the forked childs (we could set it in
kthreadd() along with PF_NOFREEZE instead).
daemonize() was changed as well. In that case testing of PF_KTHREAD is
racy, but daemonize() is hopeless anyway.
This flag is cleared in do_execve(), before search_binary_handler().
Probably not the best place, we can do this in exec_mmap() or in
start_thread(), or clear it along with PF_FORKNOEXEC. But I think this
doesn't matter in practice, and if do_execve() fails kthread should die
soon.
Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: Roland McGrath <roland@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/exec.c | 1 +
include/linux/init_task.h | 2 +-
include/linux/sched.h | 1 +
kernel/exit.c | 2 +-
4 files changed, 4 insertions(+), 2 deletions(-)
diff -puN fs/exec.c~introduce-pf_kthread-flag fs/exec.c
--- a/fs/exec.c~introduce-pf_kthread-flag
+++ a/fs/exec.c
@@ -1324,6 +1324,7 @@ int do_execve(char * filename,
if (retval < 0)
goto out;
+ current->flags &= ~PF_KTHREAD;
retval = search_binary_handler(bprm,regs);
if (retval >= 0) {
/* execve success */
diff -puN include/linux/init_task.h~introduce-pf_kthread-flag include/linux/init_task.h
--- a/include/linux/init_task.h~introduce-pf_kthread-flag
+++ a/include/linux/init_task.h
@@ -122,7 +122,7 @@ extern struct group_info init_groups;
.state = 0, \
.stack = &init_thread_info, \
.usage = ATOMIC_INIT(2), \
- .flags = 0, \
+ .flags = PF_KTHREAD, \
.lock_depth = -1, \
.prio = MAX_PRIO-20, \
.static_prio = MAX_PRIO-20, \
diff -puN include/linux/sched.h~introduce-pf_kthread-flag include/linux/sched.h
--- a/include/linux/sched.h~introduce-pf_kthread-flag
+++ a/include/linux/sched.h
@@ -1508,6 +1508,7 @@ static inline void put_task_struct(struc
#define PF_MEMPOLICY 0x10000000 /* Non-default NUMA mempolicy */
#define PF_MUTEX_TESTER 0x20000000 /* Thread belongs to the rt mutex tester */
#define PF_FREEZER_SKIP 0x40000000 /* Freezer should not count it as freezeable */
+#define PF_KTHREAD 0x80000000 /* I am a kernel thread */
/*
* Only the _current_ task can read/write to tsk->flags, but other
diff -puN kernel/exit.c~introduce-pf_kthread-flag kernel/exit.c
--- a/kernel/exit.c~introduce-pf_kthread-flag
+++ a/kernel/exit.c
@@ -421,7 +421,7 @@ void daemonize(const char *name, ...)
* We don't want to have TIF_FREEZE set if the system-wide hibernation
* or suspend transition begins right now.
*/
- current->flags |= PF_NOFREEZE;
+ current->flags |= (PF_NOFREEZE | PF_KTHREAD);
if (current->nsproxy != &init_nsproxy) {
get_nsproxy(&init_nsproxy);
_
Patches currently in -mm which might be from oleg@xxxxxxxxxx are
vt-fix-vc_resize-locking.patch
introduce-pf_kthread-flag.patch
kill-pf_borrowed_mm-in-favour-of-pf_kthread.patch
coredump-zap_threads-must-skip-kernel-threads.patch
uml-activate_mm-remove-the-dead-pf_borrowed_mm-check.patch
posix-timers-timer_delete-remove-the-bogus-it_process-=-null-check.patch
posix-timers-release_posix_timer-kill-the-bogus-put_task_struct-it_process.patch
signals-collect_signal-remove-the-unneeded-sigismember-check.patch
signals-collect_signal-simplify-the-still_pending-logic.patch
signals-change-collect_signal-to-return-void.patch
__exit_signal-dont-take-rcu-lock.patch
signals-dequeue_signal-dont-check-signal_group_exit-when-setting-signal_stop_dequeued.patch
signals-do_signal_stop-kill-the-signal_unkillable-check.patch
coredump-zap_threads-comments-use-while_each_thread.patch
distinct-tgid-tid-i-o-statistics.patch
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