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From: Lee Jones <lee.jones@linaro.org>
To: stable@vger.kernel.org
Cc: Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Lee Jones <lee.jones@linaro.org>
Subject: [PATCH 04/12] exit/exec: Seperate mm_release()
Date: Mon,  1 Feb 2021 10:01:35 +0000	[thread overview]
Message-ID: <20210201100143.2028618-5-lee.jones@linaro.org> (raw)
In-Reply-To: <20210201100143.2028618-1-lee.jones@linaro.org>

From: Thomas Gleixner <tglx@linutronix.de>

commit 4610ba7ad877fafc0a25a30c6c82015304120426 upstream.

mm_release() contains the futex exit handling. mm_release() is called from
do_exit()->exit_mm() and from exec()->exec_mm().

In the exit_mm() case PF_EXITING and the futex state is updated. In the
exec_mm() case these states are not touched.

As the futex exit code needs further protections against exit races, this
needs to be split into two functions.

Preparatory only, no functional change.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20191106224556.240518241@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
---
 fs/exec.c             |  2 +-
 include/linux/sched.h |  6 ++++--
 kernel/exit.c         |  2 +-
 kernel/fork.c         | 12 +++++++++++-
 4 files changed, 17 insertions(+), 5 deletions(-)

diff --git a/fs/exec.c b/fs/exec.c
index cd5da140f94cb..319a1f5732fa9 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -1021,7 +1021,7 @@ static int exec_mmap(struct mm_struct *mm)
 	/* Notify parent that we're no longer interested in the old VM */
 	tsk = current;
 	old_mm = current->mm;
-	mm_release(tsk, old_mm);
+	exec_mm_release(tsk, old_mm);
 
 	if (old_mm) {
 		sync_mm_rss(old_mm);
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 4de48b251447f..fcbe5904cbd97 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -2955,8 +2955,10 @@ extern struct mm_struct *get_task_mm(struct task_struct *task);
  * succeeds.
  */
 extern struct mm_struct *mm_access(struct task_struct *task, unsigned int mode);
-/* Remove the current tasks stale references to the old mm_struct */
-extern void mm_release(struct task_struct *, struct mm_struct *);
+/* Remove the current tasks stale references to the old mm_struct on exit() */
+extern void exit_mm_release(struct task_struct *, struct mm_struct *);
+/* Remove the current tasks stale references to the old mm_struct on exec() */
+extern void exec_mm_release(struct task_struct *, struct mm_struct *);
 
 #ifdef CONFIG_HAVE_COPY_THREAD_TLS
 extern int copy_thread_tls(unsigned long, unsigned long, unsigned long,
diff --git a/kernel/exit.c b/kernel/exit.c
index 969e1468f2538..b65285f5ee0c9 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -464,7 +464,7 @@ static void exit_mm(struct task_struct *tsk)
 	struct mm_struct *mm = tsk->mm;
 	struct core_state *core_state;
 
-	mm_release(tsk, mm);
+	exit_mm_release(tsk, mm);
 	if (!mm)
 		return;
 	sync_mm_rss(mm);
diff --git a/kernel/fork.c b/kernel/fork.c
index 000447bfcfde5..ad9dbbf03d7bc 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1082,7 +1082,7 @@ static int wait_for_vfork_done(struct task_struct *child,
  * restoring the old one. . .
  * Eric Biederman 10 January 1998
  */
-void mm_release(struct task_struct *tsk, struct mm_struct *mm)
+static void mm_release(struct task_struct *tsk, struct mm_struct *mm)
 {
 	/* Get rid of any futexes when releasing the mm */
 	futex_mm_release(tsk);
@@ -1119,6 +1119,16 @@ void mm_release(struct task_struct *tsk, struct mm_struct *mm)
 		complete_vfork_done(tsk);
 }
 
+void exit_mm_release(struct task_struct *tsk, struct mm_struct *mm)
+{
+	mm_release(tsk, mm);
+}
+
+void exec_mm_release(struct task_struct *tsk, struct mm_struct *mm)
+{
+	mm_release(tsk, mm);
+}
+
 /*
  * Allocate a new mm structure and copy contents from the
  * mm structure of the passed in task structure.
-- 
2.25.1


  parent reply	other threads:[~2021-02-01 10:02 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-01 10:01 [PATCH 4.9 00/12] Futex back-port from v4.14 Lee Jones
2021-02-01 10:01 ` [PATCH 01/12] y2038: futex: Move compat implementation into futex.c Lee Jones
2021-02-01 10:01 ` [PATCH 02/12] futex: Move futex exit handling into futex code Lee Jones
2021-02-01 10:01 ` [PATCH 03/12] futex: Replace PF_EXITPIDONE with a state Lee Jones
2021-02-01 10:01 ` Lee Jones [this message]
2021-02-01 10:01 ` [PATCH 05/12] futex: Split futex_mm_release() for exit/exec Lee Jones
2021-02-01 10:01 ` [PATCH 06/12] futex: Set task::futex_state to DEAD right after handling futex exit Lee Jones
2021-02-01 10:01 ` [PATCH 07/12] futex: Mark the begin of futex exit explicitly Lee Jones
2021-02-01 10:01 ` [PATCH 08/12] futex: Sanitize exit state handling Lee Jones
2021-02-01 10:01 ` [PATCH 09/12] futex: Provide state handling for exec() as well Lee Jones
2021-02-01 10:01 ` [PATCH 10/12] futex: Add mutex around futex exit Lee Jones
2021-02-01 10:01 ` [PATCH 11/12] futex: Provide distinct return value when owner is exiting Lee Jones
2021-02-01 10:01 ` [PATCH 12/12] futex: Prevent exit livelock Lee Jones
2021-02-01 11:25 ` [PATCH 4.9 00/12] Futex back-port from v4.14 Greg KH
  -- strict thread matches above, loose matches on Subject: below --
2021-02-01 15:12 [PATCH 4.4 00/12] Futex back-port from v4.9 Lee Jones
2021-02-01 15:12 ` [PATCH 04/12] exit/exec: Seperate mm_release() Lee Jones
2019-11-06 21:55 [patch 00/12] futex: Cure robust/PI futex exit races Thomas Gleixner
2019-11-06 21:55 ` [patch 04/12] exit/exec: Seperate mm_release() Thomas Gleixner

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