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From: Thomas Gleixner <tglx@linutronix.de>
To: LKML <linux-kernel@vger.kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@kernel.org>, Darren Hart <darren@dvhart.com>,
	Yi Wang <wang.yi59@zte.com.cn>, Yang Tao <yang.tao172@zte.com.cn>,
	Oleg Nesterov <oleg@redhat.com>,
	Florian Weimer <fweimer@redhat.com>,
	Carlos O'Donell <carlos@redhat.com>,
	Alexander Viro <viro@zeniv.linux.org.uk>
Subject: [patch 04/12] exit/exec: Seperate mm_release()
Date: Wed, 06 Nov 2019 22:55:38 +0100
Message-ID: <20191106224556.240518241@linutronix.de> (raw)
In-Reply-To: <20191106215534.241796846@linutronix.de>

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>
---
 fs/exec.c                |    2 +-
 include/linux/sched/mm.h |    6 ++++--
 kernel/exit.c            |    2 +-
 kernel/fork.c            |   12 +++++++++++-
 4 files changed, 17 insertions(+), 5 deletions(-)

--- a/fs/exec.c
+++ b/fs/exec.c
@@ -1015,7 +1015,7 @@ static int exec_mmap(struct mm_struct *m
 	/* 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);
--- a/include/linux/sched/mm.h
+++ b/include/linux/sched/mm.h
@@ -117,8 +117,10 @@ extern struct mm_struct *get_task_mm(str
  * 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_MEMCG
 extern void mm_update_next_owner(struct mm_struct *mm);
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -437,7 +437,7 @@ static void exit_mm(void)
 	struct mm_struct *mm = current->mm;
 	struct core_state *core_state;
 
-	mm_release(current, mm);
+	exit_mm_release(current, mm);
 	if (!mm)
 		return;
 	sync_mm_rss(mm);
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1283,7 +1283,7 @@ static int wait_for_vfork_done(struct ta
  * 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);
@@ -1320,6 +1320,16 @@ void mm_release(struct task_struct *tsk,
 		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);
+}
+
 /**
  * dup_mm() - duplicates an existing mm structure
  * @tsk: the task_struct with which the new mm will be associated.



  parent reply index

Thread overview: 53+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-11-06 21:55 [patch 00/12] futex: Cure robust/PI futex exit races Thomas Gleixner
2019-11-06 21:55 ` [patch 01/12] futex: Prevent robust futex exit race Thomas Gleixner
2019-11-06 21:55 ` [patch 02/12] futex: Move futex exit handling into futex code Thomas Gleixner
2019-11-07  9:24   ` Peter Zijlstra
2019-11-07  9:38     ` Thomas Gleixner
2019-11-15 18:19   ` [tip: locking/core] " tip-bot2 for Thomas Gleixner
2019-11-16 20:53     ` Borislav Petkov
2019-11-20  9:38   ` tip-bot2 for Thomas Gleixner
2019-11-06 21:55 ` [patch 03/12] futex: Replace PF_EXITPIDONE with a state Thomas Gleixner
2019-11-15 18:19   ` [tip: locking/core] " tip-bot2 for Thomas Gleixner
2019-11-20  9:38   ` tip-bot2 for Thomas Gleixner
2019-11-06 21:55 ` Thomas Gleixner [this message]
2019-11-15 18:19   ` [tip: locking/core] exit/exec: Seperate mm_release() tip-bot2 for Thomas Gleixner
2019-11-20  9:38   ` tip-bot2 for Thomas Gleixner
2019-11-06 21:55 ` [patch 05/12] futex: Split futex_mm_release() for exit/exec Thomas Gleixner
2019-11-15 18:19   ` [tip: locking/core] " tip-bot2 for Thomas Gleixner
2019-11-20  9:38   ` tip-bot2 for Thomas Gleixner
2019-11-06 21:55 ` [patch 06/12] futex: Set task::futex state to DEAD right after handling futex exit Thomas Gleixner
2019-11-15 18:19   ` [tip: locking/core] futex: Set task::futex_state " tip-bot2 for Thomas Gleixner
2019-11-20  9:38   ` tip-bot2 for Thomas Gleixner
2019-11-06 21:55 ` [patch 07/12] futex: Mark the begin of futex exit explicitly Thomas Gleixner
2019-11-15 18:19   ` [tip: locking/core] " tip-bot2 for Thomas Gleixner
2019-11-20  9:38   ` tip-bot2 for Thomas Gleixner
2019-11-06 21:55 ` [patch 08/12] futex: Sanitize exit state handling Thomas Gleixner
2019-11-07  9:38   ` Peter Zijlstra
2019-11-15 18:19   ` [tip: locking/core] " tip-bot2 for Thomas Gleixner
2019-11-20  9:38   ` tip-bot2 for Thomas Gleixner
2019-11-06 21:55 ` [patch 09/12] futex: Provide state handling for exec() as well Thomas Gleixner
2019-11-07  9:49   ` Peter Zijlstra
2019-11-07  9:54     ` Thomas Gleixner
2019-11-15 18:19   ` [tip: locking/core] " tip-bot2 for Thomas Gleixner
2019-11-20  9:38   ` tip-bot2 for Thomas Gleixner
2019-11-06 21:55 ` [patch 10/12] futex: Add mutex around futex exit Thomas Gleixner
2019-11-15 18:19   ` [tip: locking/core] " tip-bot2 for Thomas Gleixner
2019-11-20  9:38   ` tip-bot2 for Thomas Gleixner
2019-11-06 21:55 ` [patch 11/12] futex: Provide distinct return value when owner is exiting Thomas Gleixner
2019-11-15 18:19   ` [tip: locking/core] " tip-bot2 for Thomas Gleixner
2019-11-20  9:38   ` tip-bot2 for Thomas Gleixner
2019-11-06 21:55 ` [patch 12/12] futex: Prevent exit livelock Thomas Gleixner
2019-11-15 18:19   ` [tip: locking/core] " tip-bot2 for Thomas Gleixner
2019-11-20  9:38   ` tip-bot2 for Thomas Gleixner
2019-11-07  8:29 ` [patch 00/12] futex: Cure robust/PI futex exit races Ingo Molnar
2019-11-07  8:41 ` Ingo Molnar
2019-11-07  9:40 ` Peter Zijlstra
2019-11-07 15:03 ` Oleg Nesterov
2019-11-07 22:29 ` Florian Weimer
2019-11-07 22:40   ` Florian Weimer
2019-11-08  7:38     ` Florian Weimer
2019-11-08  9:18       ` Thomas Gleixner
2019-11-08 10:17         ` Florian Weimer
2019-11-08 10:37           ` Thomas Gleixner
2019-11-08 11:51             ` Thomas Gleixner
2019-11-11  9:48               ` Florian Weimer

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