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Groups > linux.kernel > #1482791
| From | Andy Lutomirski <luto@kernel.org> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | [PATCH 06/12] sched: Add try_get_task_stack() and put_task_stack() |
| Date | 2016-09-13 23:40 +0200 |
| Message-ID | <sh3AS-7tK-21@gated-at.bofh.it> (permalink) |
| References | <sh3rc-7o2-3@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
There are a few places in the kernel that access stack memory
belonging to a different task. Before we can start freeing task
stacks before the task_struct is freed, we need a way for those code
paths to pin the stack.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
---
include/linux/sched.h | 16 ++++++++++++++++
init/Kconfig | 3 +++
2 files changed, 19 insertions(+)
diff --git a/include/linux/sched.h b/include/linux/sched.h
index a287e8b13549..a95867267e9f 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -3094,11 +3094,19 @@ static inline struct thread_info *task_thread_info(struct task_struct *task)
{
return &task->thread_info;
}
+
+/*
+ * When accessing the stack of a non-current task that might exit, use
+ * try_get_task_stack() instead. task_stack_page will return a pointer
+ * that could get freed out from under you.
+ */
static inline void *task_stack_page(const struct task_struct *task)
{
return task->stack;
}
+
#define setup_thread_stack(new,old) do { } while(0)
+
static inline unsigned long *end_of_stack(const struct task_struct *task)
{
return task->stack;
@@ -3134,6 +3142,14 @@ static inline unsigned long *end_of_stack(struct task_struct *p)
}
#endif
+
+static inline void *try_get_task_stack(struct task_struct *tsk)
+{
+ return task_stack_page(tsk);
+}
+
+static inline void put_task_stack(struct task_struct *tsk) {}
+
#define task_stack_end_corrupted(task) \
(*(end_of_stack(task)) != STACK_END_MAGIC)
diff --git a/init/Kconfig b/init/Kconfig
index ec8d43894b02..3b9a47fe843b 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -33,6 +33,9 @@ config THREAD_INFO_IN_TASK
make this work, an arch will need to remove all thread_info fields
except flags and fix any runtime bugs.
+ One subtle change that will be needed is to use try_get_task_stack()
+ and put_task_stack() in save_thread_stack_tsk() and get_wchan().
+
menu "General setup"
config BROKEN
--
2.7.4
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[PATCH 00/12] thread_info cleanups and stack caching Andy Lutomirski <luto@kernel.org> - 2016-09-13 23:30 +0200
[PATCH 03/12] um: Stop conflating task_struct::stack with thread_info Andy Lutomirski <luto@kernel.org> - 2016-09-13 23:30 +0200
Re: [PATCH 03/12] um: Stop conflating task_struct::stack with thread_info Ingo Molnar <mingo@kernel.org> - 2016-09-15 08:30 +0200
[tip:x86/asm] um/Stop conflating task_struct::stack with thread_info tip-bot for Linus Torvalds <tipbot@zytor.com> - 2016-09-15 12:50 +0200
[PATCH 12/12] fork: Cache two thread stacks per cpu if CONFIG_VMAP_STACK is set Andy Lutomirski <luto@kernel.org> - 2016-09-13 23:40 +0200
[PATCH 01/12] x86/asm: Move 'status' from struct thread_info to struct thread_struct Andy Lutomirski <luto@kernel.org> - 2016-09-13 23:40 +0200
[tip:x86/asm] x86/asm: Move the thread_info::status field to thread_struct tip-bot for Andy Lutomirski <tipbot@zytor.com> - 2016-09-15 12:50 +0200
[PATCH 10/12] lib/syscall: Pin the task stack in collect_syscall() Andy Lutomirski <luto@kernel.org> - 2016-09-13 23:40 +0200
[PATCH 08/12] x86/dumpstack: Pin the target stack in save_stack_trace_tsk() Andy Lutomirski <luto@kernel.org> - 2016-09-13 23:40 +0200
Re: [PATCH 08/12] x86/dumpstack: Pin the target stack in save_stack_trace_tsk() Josh Poimboeuf <jpoimboe@redhat.com> - 2016-09-14 17:00 +0200
Re: [PATCH 08/12] x86/dumpstack: Pin the target stack in save_stack_trace_tsk() Andy Lutomirski <luto@amacapital.net> - 2016-09-14 20:30 +0200
Re: [PATCH 08/12] x86/dumpstack: Pin the target stack in save_stack_trace_tsk() Josh Poimboeuf <jpoimboe@redhat.com> - 2016-09-14 20:40 +0200
Re: [PATCH 08/12] x86/dumpstack: Pin the target stack in save_stack_trace_tsk() Andy Lutomirski <luto@amacapital.net> - 2016-09-15 20:10 +0200
Re: [PATCH 08/12] x86/dumpstack: Pin the target stack in save_stack_trace_tsk() Josh Poimboeuf <jpoimboe@redhat.com> - 2016-09-15 20:40 +0200
Re: [PATCH 08/12] x86/dumpstack: Pin the target stack in save_stack_trace_tsk() Andy Lutomirski <luto@amacapital.net> - 2016-09-15 20:50 +0200
Re: [PATCH 08/12] x86/dumpstack: Pin the target stack in save_stack_trace_tsk() Josh Poimboeuf <jpoimboe@redhat.com> - 2016-09-15 21:20 +0200
Re: [PATCH 08/12] x86/dumpstack: Pin the target stack in save_stack_trace_tsk() Peter Zijlstra <peterz@infradead.org> - 2016-09-16 09:50 +0200
Re: [PATCH 08/12] x86/dumpstack: Pin the target stack in save_stack_trace_tsk() Andy Lutomirski <luto@amacapital.net> - 2016-09-16 17:20 +0200
Re: [PATCH 08/12] x86/dumpstack: Pin the target stack in save_stack_trace_tsk() Andy Lutomirski <luto@kernel.org> - 2016-09-16 17:40 +0200
Re: [PATCH 08/12] x86/dumpstack: Pin the target stack in save_stack_trace_tsk() Peter Zijlstra <peterz@infradead.org> - 2016-09-16 18:40 +0200
Re: [PATCH 08/12] x86/dumpstack: Pin the target stack in save_stack_trace_tsk() Peter Zijlstra <peterz@infradead.org> - 2016-09-16 17:40 +0200
Re: [PATCH 08/12] x86/dumpstack: Pin the target stack in save_stack_trace_tsk() Ingo Molnar <mingo@kernel.org> - 2016-09-15 08:40 +0200
Re: [PATCH 08/12] x86/dumpstack: Pin the target stack in save_stack_trace_tsk() Ingo Molnar <mingo@kernel.org> - 2016-09-15 11:30 +0200
[PATCH 09/12] x86/process: Pin the target stack in get_wchan() Andy Lutomirski <luto@kernel.org> - 2016-09-13 23:40 +0200
Re: [PATCH 09/12] x86/process: Pin the target stack in get_wchan() Jann Horn <jann@thejh.net> - 2016-09-17 04:10 +0200
Re: [PATCH 09/12] x86/process: Pin the target stack in get_wchan() Andy Lutomirski <luto@amacapital.net> - 2016-09-23 00:50 +0200
Re: [PATCH 09/12] x86/process: Pin the target stack in get_wchan() Andy Lutomirski <luto@amacapital.net> - 2016-09-23 01:00 +0200
Re: [PATCH 09/12] x86/process: Pin the target stack in get_wchan() Jann Horn <jann@thejh.net> - 2016-09-23 09:50 +0200
[PATCH 06/12] sched: Add try_get_task_stack() and put_task_stack() Andy Lutomirski <luto@kernel.org> - 2016-09-13 23:40 +0200
[PATCH 02/12] x86/entry: Get rid of pt_regs_to_thread_info() Andy Lutomirski <luto@kernel.org> - 2016-09-13 23:40 +0200
Re: [PATCH 02/12] x86/entry: Get rid of pt_regs_to_thread_info() Ingo Molnar <mingo@kernel.org> - 2016-09-15 08:30 +0200
[tip:x86/asm] x86/entry: Get rid of pt_regs_to_thread_info() tip-bot for Linus Torvalds <tipbot@zytor.com> - 2016-09-15 12:50 +0200
[PATCH 05/12] x86: Move thread_info into task_struct Andy Lutomirski <luto@kernel.org> - 2016-09-13 23:40 +0200
[tip:x86/asm] x86: Move thread_info into task_struct tip-bot for Andy Lutomirski <tipbot@zytor.com> - 2016-09-15 12:50 +0200
[PATCH 04/12] sched: Allow putting thread_info into task_struct Andy Lutomirski <luto@kernel.org> - 2016-09-13 23:40 +0200
[tip:x86/asm] sched/core: Allow putting thread_info into task_struct tip-bot for Andy Lutomirski <tipbot@zytor.com> - 2016-09-15 12:50 +0200
[PATCH 11/12] sched: Free the stack early if CONFIG_THREAD_INFO_IN_TASK Andy Lutomirski <luto@kernel.org> - 2016-09-13 23:40 +0200
[PATCH 07/12] kthread: to_live_kthread() needs try_get_task_stack() Andy Lutomirski <luto@kernel.org> - 2016-09-13 23:40 +0200
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