From: "tip-bot2 for Mathieu Desnoyers" <tip-bot2@linutronix.de>
To: linux-tip-commits@vger.kernel.org
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
"Peter Zijlstra (Intel)" <peterz@infradead.org>,
Chris Metcalf <cmetcalf@ezchip.com>,
Christoph Lameter <cl@linux.com>,
"Eric W. Biederman" <ebiederm@xmission.com>,
Kirill Tkhai <tkhai@yandex.ru>,
Linus Torvalds <torvalds@linux-foundation.org>,
Mike Galbraith <efault@gmx.de>, Oleg Nesterov <oleg@redhat.com>,
"Paul E. McKenney" <paulmck@linux.ibm.com>,
"Russell King - ARM Linux admin" <linux@armlinux.org.uk>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@kernel.org>, Borislav Petkov <bp@alien8.de>,
linux-kernel@vger.kernel.org
Subject: [tip: sched/urgent] sched/membarrier: Return -ENOMEM to userspace on memory allocation failure
Date: Fri, 27 Sep 2019 08:10:42 -0000 [thread overview]
Message-ID: <156957184244.9866.6327974056677601202.tip-bot2@tip-bot2> (raw)
In-Reply-To: <20190919173705.2181-8-mathieu.desnoyers@efficios.com>
The following commit has been merged into the sched/urgent branch of tip:
Commit-ID: c172e0a3e8e65a4c6fffec5bc4d6de08d6f894f7
Gitweb: https://git.kernel.org/tip/c172e0a3e8e65a4c6fffec5bc4d6de08d6f894f7
Author: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
AuthorDate: Thu, 19 Sep 2019 13:37:05 -04:00
Committer: Ingo Molnar <mingo@kernel.org>
CommitterDate: Wed, 25 Sep 2019 17:42:31 +02:00
sched/membarrier: Return -ENOMEM to userspace on memory allocation failure
Remove the IPI fallback code from membarrier to deal with very
infrequent cpumask memory allocation failure. Use GFP_KERNEL rather
than GFP_NOWAIT, and relax the blocking guarantees for the expedited
membarrier system call commands, allowing it to block if waiting for
memory to be made available.
In addition, now -ENOMEM can be returned to user-space if the cpumask
memory allocation fails.
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Chris Metcalf <cmetcalf@ezchip.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Kirill Tkhai <tkhai@yandex.ru>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Paul E. McKenney <paulmck@linux.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Russell King - ARM Linux admin <linux@armlinux.org.uk>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20190919173705.2181-8-mathieu.desnoyers@efficios.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
kernel/sched/membarrier.c | 63 ++++++++++++--------------------------
1 file changed, 20 insertions(+), 43 deletions(-)
diff --git a/kernel/sched/membarrier.c b/kernel/sched/membarrier.c
index fced54a..a39bed2 100644
--- a/kernel/sched/membarrier.c
+++ b/kernel/sched/membarrier.c
@@ -66,7 +66,6 @@ void membarrier_exec_mmap(struct mm_struct *mm)
static int membarrier_global_expedited(void)
{
int cpu;
- bool fallback = false;
cpumask_var_t tmpmask;
if (num_online_cpus() == 1)
@@ -78,15 +77,8 @@ static int membarrier_global_expedited(void)
*/
smp_mb(); /* system call entry is not a mb. */
- /*
- * Expedited membarrier commands guarantee that they won't
- * block, hence the GFP_NOWAIT allocation flag and fallback
- * implementation.
- */
- if (!zalloc_cpumask_var(&tmpmask, GFP_NOWAIT)) {
- /* Fallback for OOM. */
- fallback = true;
- }
+ if (!zalloc_cpumask_var(&tmpmask, GFP_KERNEL))
+ return -ENOMEM;
cpus_read_lock();
rcu_read_lock();
@@ -117,18 +109,15 @@ static int membarrier_global_expedited(void)
if (p->flags & PF_KTHREAD)
continue;
- if (!fallback)
- __cpumask_set_cpu(cpu, tmpmask);
- else
- smp_call_function_single(cpu, ipi_mb, NULL, 1);
+ __cpumask_set_cpu(cpu, tmpmask);
}
rcu_read_unlock();
- if (!fallback) {
- preempt_disable();
- smp_call_function_many(tmpmask, ipi_mb, NULL, 1);
- preempt_enable();
- free_cpumask_var(tmpmask);
- }
+
+ preempt_disable();
+ smp_call_function_many(tmpmask, ipi_mb, NULL, 1);
+ preempt_enable();
+
+ free_cpumask_var(tmpmask);
cpus_read_unlock();
/*
@@ -143,7 +132,6 @@ static int membarrier_global_expedited(void)
static int membarrier_private_expedited(int flags)
{
int cpu;
- bool fallback = false;
cpumask_var_t tmpmask;
struct mm_struct *mm = current->mm;
@@ -168,15 +156,8 @@ static int membarrier_private_expedited(int flags)
*/
smp_mb(); /* system call entry is not a mb. */
- /*
- * Expedited membarrier commands guarantee that they won't
- * block, hence the GFP_NOWAIT allocation flag and fallback
- * implementation.
- */
- if (!zalloc_cpumask_var(&tmpmask, GFP_NOWAIT)) {
- /* Fallback for OOM. */
- fallback = true;
- }
+ if (!zalloc_cpumask_var(&tmpmask, GFP_KERNEL))
+ return -ENOMEM;
cpus_read_lock();
rcu_read_lock();
@@ -195,20 +176,16 @@ static int membarrier_private_expedited(int flags)
continue;
rcu_read_lock();
p = rcu_dereference(cpu_rq(cpu)->curr);
- if (p && p->mm == mm) {
- if (!fallback)
- __cpumask_set_cpu(cpu, tmpmask);
- else
- smp_call_function_single(cpu, ipi_mb, NULL, 1);
- }
+ if (p && p->mm == mm)
+ __cpumask_set_cpu(cpu, tmpmask);
}
rcu_read_unlock();
- if (!fallback) {
- preempt_disable();
- smp_call_function_many(tmpmask, ipi_mb, NULL, 1);
- preempt_enable();
- free_cpumask_var(tmpmask);
- }
+
+ preempt_disable();
+ smp_call_function_many(tmpmask, ipi_mb, NULL, 1);
+ preempt_enable();
+
+ free_cpumask_var(tmpmask);
cpus_read_unlock();
/*
@@ -264,7 +241,7 @@ static int sync_runqueues_membarrier_state(struct mm_struct *mm)
struct rq *rq = cpu_rq(cpu);
struct task_struct *p;
- p = rcu_dereference(&rq->curr);
+ p = rcu_dereference(rq->curr);
if (p && p->mm == mm)
__cpumask_set_cpu(cpu, tmpmask);
}
next prev parent reply other threads:[~2019-09-27 8:11 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-19 17:36 [RFC PATCH for 5.4 0/7] Membarrier fixes and cleanups Mathieu Desnoyers
2019-09-19 17:36 ` [RFC PATCH for 5.4 1/7] Fix: sched/membarrier: Private expedited registration check Mathieu Desnoyers
2019-09-27 8:10 ` [tip: sched/urgent] sched/membarrier: Fix private " tip-bot2 for Mathieu Desnoyers
2019-09-19 17:37 ` [RFC PATCH for 5.4 2/7] Cleanup: sched/membarrier: Remove redundant check Mathieu Desnoyers
2019-09-27 8:10 ` [tip: sched/urgent] " tip-bot2 for Mathieu Desnoyers
2019-09-19 17:37 ` [RFC PATCH for 5.4 3/7] Cleanup: sched/membarrier: Only sync_core before usermode for same mm Mathieu Desnoyers
2019-09-27 8:10 ` [tip: sched/urgent] sched/membarrier: Call sync_core only " tip-bot2 for Mathieu Desnoyers
2019-09-19 17:37 ` [RFC PATCH for 5.4 4/7] Fix: sched/membarrier: p->mm->membarrier_state racy load (v4) Mathieu Desnoyers
2019-09-27 8:10 ` [tip: sched/urgent] sched/membarrier: Fix p->mm->membarrier_state racy load tip-bot2 for Mathieu Desnoyers
2019-10-01 8:44 ` Ingo Molnar
2019-10-01 8:50 ` Peter Zijlstra
2019-10-01 19:34 ` [tip: sched/urgent] membarrier: Fix RCU locking bug caused by faulty merge tip-bot2 for Peter Zijlstra
2019-09-19 17:37 ` [RFC PATCH for 5.4 5/7] selftests: sched/membarrier: Add multi-threaded test Mathieu Desnoyers
2019-09-27 8:10 ` [tip: sched/urgent] selftests, " tip-bot2 for Mathieu Desnoyers
2019-09-19 17:37 ` [RFC PATCH for 5.4 6/7] sched/membarrier: Skip IPIs when mm->mm_users == 1 Mathieu Desnoyers
2019-09-27 8:10 ` [tip: sched/urgent] " tip-bot2 for Mathieu Desnoyers
2019-09-19 17:37 ` [RFC PATCH for 5.4 7/7] sched/membarrier: Return -ENOMEM to userspace on memory allocation failure Mathieu Desnoyers
2019-09-27 8:10 ` tip-bot2 for Mathieu Desnoyers [this message]
2019-09-23 9:06 ` [RFC PATCH for 5.4 0/7] Membarrier fixes and cleanups Peter Zijlstra
2019-09-23 14:55 ` Mathieu Desnoyers
2019-09-25 8:07 ` Peter Zijlstra
2019-09-25 15:50 ` Mathieu Desnoyers
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=156957184244.9866.6327974056677601202.tip-bot2@tip-bot2 \
--to=tip-bot2@linutronix.de \
--cc=bp@alien8.de \
--cc=cl@linux.com \
--cc=cmetcalf@ezchip.com \
--cc=ebiederm@xmission.com \
--cc=efault@gmx.de \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-tip-commits@vger.kernel.org \
--cc=linux@armlinux.org.uk \
--cc=mathieu.desnoyers@efficios.com \
--cc=mingo@kernel.org \
--cc=oleg@redhat.com \
--cc=paulmck@linux.ibm.com \
--cc=peterz@infradead.org \
--cc=tglx@linutronix.de \
--cc=tkhai@yandex.ru \
--cc=torvalds@linux-foundation.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).