From: Andy Lutomirski <luto@kernel.org>
To: x86@kernel.org
Cc: Borislav Petkov <bp@alien8.de>,
linux-kernel@vger.kernel.org, Brian Gerst <brgerst@gmail.com>,
Jann Horn <jann@thejh.net>, Oleg Nesterov <oleg@redhat.com>,
Andy Lutomirski <luto@kernel.org>
Subject: [PATCH 07/12] kthread: to_live_kthread() needs try_get_task_stack()
Date: Tue, 13 Sep 2016 14:29:27 -0700 [thread overview]
Message-ID: <9cd79e91d82868147f2957e88d68cbf574862f68.1473801993.git.luto@kernel.org> (raw)
In-Reply-To: <cover.1473801993.git.luto@kernel.org>
In-Reply-To: <cover.1473801993.git.luto@kernel.org>
From: Oleg Nesterov <oleg@redhat.com>
get_task_struct(tsk) no longer pins tsk->stack so all users of
to_live_kthread() should do try_get_task_stack/put_task_stack to protect
"struct kthread" which lives on kthread's stack.
TODO: Kill to_live_kthread(), perhaps we can even kill "struct kthread" too,
and rework kthread_stop(), it can use task_work_add() to sync with the exiting
kernel thread.
Message-Id: <20160629180357.GA7178@redhat.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Andy Lutomirski <luto@kernel.org>
---
kernel/kthread.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/kernel/kthread.c b/kernel/kthread.c
index 9ff173dca1ae..4ab4c3766a80 100644
--- a/kernel/kthread.c
+++ b/kernel/kthread.c
@@ -64,7 +64,7 @@ static inline struct kthread *to_kthread(struct task_struct *k)
static struct kthread *to_live_kthread(struct task_struct *k)
{
struct completion *vfork = ACCESS_ONCE(k->vfork_done);
- if (likely(vfork))
+ if (likely(vfork) && try_get_task_stack(k))
return __to_kthread(vfork);
return NULL;
}
@@ -425,8 +425,10 @@ void kthread_unpark(struct task_struct *k)
{
struct kthread *kthread = to_live_kthread(k);
- if (kthread)
+ if (kthread) {
__kthread_unpark(k, kthread);
+ put_task_stack(k);
+ }
}
EXPORT_SYMBOL_GPL(kthread_unpark);
@@ -455,6 +457,7 @@ int kthread_park(struct task_struct *k)
wait_for_completion(&kthread->parked);
}
}
+ put_task_stack(k);
ret = 0;
}
return ret;
@@ -490,6 +493,7 @@ int kthread_stop(struct task_struct *k)
__kthread_unpark(k, kthread);
wake_up_process(k);
wait_for_completion(&kthread->exited);
+ put_task_stack(k);
}
ret = k->exit_code;
put_task_struct(k);
--
2.7.4
next prev parent reply other threads:[~2016-09-13 21:30 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-13 21:29 [PATCH 00/12] thread_info cleanups and stack caching Andy Lutomirski
2016-09-13 21:29 ` [PATCH 01/12] x86/asm: Move 'status' from struct thread_info to struct thread_struct Andy Lutomirski
2016-09-15 10:41 ` [tip:x86/asm] x86/asm: Move the thread_info::status field to thread_struct tip-bot for Andy Lutomirski
2016-09-13 21:29 ` [PATCH 02/12] x86/entry: Get rid of pt_regs_to_thread_info() Andy Lutomirski
2016-09-15 6:21 ` Ingo Molnar
2016-09-15 10:42 ` [tip:x86/asm] " tip-bot for Linus Torvalds
2016-09-13 21:29 ` [PATCH 03/12] um: Stop conflating task_struct::stack with thread_info Andy Lutomirski
2016-09-15 6:21 ` Ingo Molnar
2016-09-15 10:42 ` [tip:x86/asm] um/Stop " tip-bot for Linus Torvalds
2016-09-13 21:29 ` [PATCH 04/12] sched: Allow putting thread_info into task_struct Andy Lutomirski
2016-09-15 10:43 ` [tip:x86/asm] sched/core: " tip-bot for Andy Lutomirski
2016-09-13 21:29 ` [PATCH 05/12] x86: Move " Andy Lutomirski
2016-09-15 10:43 ` [tip:x86/asm] " tip-bot for Andy Lutomirski
2016-09-13 21:29 ` [PATCH 06/12] sched: Add try_get_task_stack() and put_task_stack() Andy Lutomirski
2016-09-13 21:29 ` Andy Lutomirski [this message]
2016-09-13 21:29 ` [PATCH 08/12] x86/dumpstack: Pin the target stack in save_stack_trace_tsk() Andy Lutomirski
2016-09-14 14:55 ` Josh Poimboeuf
2016-09-14 18:22 ` Andy Lutomirski
2016-09-14 18:35 ` Josh Poimboeuf
2016-09-15 18:04 ` Andy Lutomirski
2016-09-15 18:37 ` Josh Poimboeuf
2016-09-15 18:41 ` Andy Lutomirski
2016-09-15 19:19 ` Josh Poimboeuf
2016-09-16 7:47 ` Peter Zijlstra
2016-09-16 15:12 ` Andy Lutomirski
2016-09-16 15:31 ` Peter Zijlstra
2016-09-16 15:32 ` Andy Lutomirski
2016-09-16 16:35 ` Peter Zijlstra
2016-09-15 6:37 ` Ingo Molnar
[not found] ` <CA+55aFxt=HLrELBE=BXUrWdh6LYs4gtu9S=yCruiDffq4HN80w@mail.gmail.com>
2016-09-15 9:27 ` Ingo Molnar
2016-09-13 21:29 ` [PATCH 09/12] x86/process: Pin the target stack in get_wchan() Andy Lutomirski
2016-09-17 2:00 ` Jann Horn
2016-09-22 22:44 ` Andy Lutomirski
2016-09-22 22:50 ` Andy Lutomirski
2016-09-23 7:43 ` Jann Horn
2016-09-23 18:28 ` Kees Cook
2016-09-23 18:34 ` Jann Horn
2016-09-26 5:10 ` Tycho Andersen
2016-09-13 21:29 ` [PATCH 10/12] lib/syscall: Pin the task stack in collect_syscall() Andy Lutomirski
2016-09-13 21:29 ` [PATCH 11/12] sched: Free the stack early if CONFIG_THREAD_INFO_IN_TASK Andy Lutomirski
2016-09-13 21:29 ` [PATCH 12/12] fork: Cache two thread stacks per cpu if CONFIG_VMAP_STACK is set Andy Lutomirski
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