linux-kernel - [PATCH 4.19 070/114] sched/membarrier: Call sync

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Thu, 10 Oct 2019 10:36:17 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Oleg Nesterov <oleg@...hat.com>,
        Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
        "Peter Zijlstra (Intel)" <peterz@...radead.org>,
        Chris Metcalf <cmetcalf@...hip.com>,
        Christoph Lameter <cl@...ux.com>,
        "Eric W. Biederman" <ebiederm@...ssion.com>,
        Kirill Tkhai <tkhai@...dex.ru>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Mike Galbraith <efault@....de>,
        "Paul E. McKenney" <paulmck@...ux.ibm.com>,
        Russell King - ARM Linux admin <linux@...linux.org.uk>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...nel.org>, Sasha Levin <sashal@...nel.org>
Subject: [PATCH 4.19 070/114] sched/membarrier: Call sync_core only before usermode for same mm

From: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>

[ Upstream commit 2840cf02fae627860156737e83326df354ee4ec6 ]

When the prev and next task's mm change, switch_mm() provides the core
serializing guarantees before returning to usermode. The only case
where an explicit core serialization is needed is when the scheduler
keeps the same mm for prev and next.

Suggested-by: Oleg Nesterov <oleg@...hat.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Cc: Chris Metcalf <cmetcalf@...hip.com>
Cc: Christoph Lameter <cl@...ux.com>
Cc: Eric W. Biederman <ebiederm@...ssion.com>
Cc: Kirill Tkhai <tkhai@...dex.ru>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Mike Galbraith <efault@....de>
Cc: Paul E. McKenney <paulmck@...ux.ibm.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Russell King - ARM Linux admin <linux@...linux.org.uk>
Cc: Thomas Gleixner <tglx@...utronix.de>
Link: https://lkml.kernel.org/r/20190919173705.2181-4-mathieu.desnoyers@efficios.com
Signed-off-by: Ingo Molnar <mingo@...nel.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 include/linux/sched/mm.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/include/linux/sched/mm.h b/include/linux/sched/mm.h
index 0d10b7ce0da74..e9d4e389aed93 100644
--- a/include/linux/sched/mm.h
+++ b/include/linux/sched/mm.h
@@ -330,6 +330,8 @@ enum {
 
 static inline void membarrier_mm_sync_core_before_usermode(struct mm_struct *mm)
 {
+	if (current->mm != mm)
+		return;
 	if (likely(!(atomic_read(&mm->membarrier_state) &
 		     MEMBARRIER_STATE_PRIVATE_EXPEDITED_SYNC_CORE)))
 		return;
-- 
2.20.1