[ANNOUNCE] 4.14.172-rt78

From: Tom Zanussi
Date: Mon Mar 16 2020 - 12:32:18 EST

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Hello RT Folks!

I'm pleased to announce the 4.14.172-rt78 stable release.

You can get this release via the git tree at:

git://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-stable-rt.git

branch: v4.14-rt
Head SHA1: 5c41599ad817e04c88d08a46941fbeafdf778e3d

Or to build 4.14.172-rt78 directly, the following patches should be applied:

https://www.kernel.org/pub/linux/kernel/v4.x/linux-4.14.tar.xz

https://www.kernel.org/pub/linux/kernel/v4.x/patch-4.14.172.xz

https://www.kernel.org/pub/linux/kernel/projects/rt/4.14/patch-4.14.172-rt78.patch.xz

You can also build from 4.14.172-rt77 by applying the incremental patch:

https://www.kernel.org/pub/linux/kernel/projects/rt/4.14/incr/patch-4.14.172-rt77-rt78.patch.xz

Enjoy!

Tom

Changes from v4.14.172-rt77:
---

Matt Fleming (1):
mm/memcontrol: Move misplaced local_unlock_irqrestore()

Scott Wood (2):
sched: migrate_enable: Use per-cpu cpu_stop_work
sched: migrate_enable: Remove __schedule() call

Sebastian Andrzej Siewior (4):
userfaultfd: Use a seqlock instead of seqcount
locallock: Include header for the `current' macro
drm/vmwgfx: Drop preempt_disable() in vmw_fifo_ping_host()
tracing: make preempt_lazy and migrate_disable counter smaller

Tom Zanussi (1):
Linux 4.14.172-rt78
---
drivers/gpu/drm/vmwgfx/vmwgfx_fifo.c | 2 --
fs/userfaultfd.c | 12 ++++++------
include/linux/locallock.h | 1 +
include/linux/trace_events.h | 3 +--
kernel/sched/core.c | 23 ++++++++++++++---------
kernel/trace/trace_events.c | 4 ++--
localversion-rt | 2 +-
mm/memcontrol.c | 2 +-
8 files changed, 26 insertions(+), 23 deletions(-)
---
diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_fifo.c b/drivers/gpu/drm/vmwgfx/vmwgfx_fifo.c
index a1c68e6a689e3..713f202fca2cd 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_fifo.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_fifo.c
@@ -167,10 +167,8 @@ void vmw_fifo_ping_host(struct vmw_private *dev_priv, uint32_t reason)
{
u32 *fifo_mem = dev_priv->mmio_virt;

- preempt_disable();
if (cmpxchg(fifo_mem + SVGA_FIFO_BUSY, 0, 1) == 0)
vmw_write(dev_priv, SVGA_REG_SYNC, reason);
- preempt_enable();
}

void vmw_fifo_release(struct vmw_private *dev_priv, struct vmw_fifo_state *fifo)
diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c
index e2b2196fd9428..71886a8e8f71b 100644
--- a/fs/userfaultfd.c
+++ b/fs/userfaultfd.c
@@ -51,7 +51,7 @@ struct userfaultfd_ctx {
/* waitqueue head for events */
wait_queue_head_t event_wqh;
/* a refile sequence protected by fault_pending_wqh lock */
- struct seqcount refile_seq;
+ seqlock_t refile_seq;
/* pseudo fd refcounting */
atomic_t refcount;
/* userfaultfd syscall flags */
@@ -1047,7 +1047,7 @@ static ssize_t userfaultfd_ctx_read(struct userfaultfd_ctx *ctx, int no_wait,
* waitqueue could become empty if this is the
* only userfault.
*/
- write_seqcount_begin(&ctx->refile_seq);
+ write_seqlock(&ctx->refile_seq);

/*
* The fault_pending_wqh.lock prevents the uwq
@@ -1073,7 +1073,7 @@ static ssize_t userfaultfd_ctx_read(struct userfaultfd_ctx *ctx, int no_wait,
list_del(&uwq->wq.entry);
__add_wait_queue(&ctx->fault_wqh, &uwq->wq);

- write_seqcount_end(&ctx->refile_seq);
+ write_sequnlock(&ctx->refile_seq);

/* careful to always initialize msg if ret == 0 */
*msg = uwq->msg;
@@ -1246,11 +1246,11 @@ static __always_inline void wake_userfault(struct userfaultfd_ctx *ctx,
* sure we've userfaults to wake.
*/
do {
- seq = read_seqcount_begin(&ctx->refile_seq);
+ seq = read_seqbegin(&ctx->refile_seq);
need_wakeup = waitqueue_active(&ctx->fault_pending_wqh) ||
waitqueue_active(&ctx->fault_wqh);
cond_resched();
- } while (read_seqcount_retry(&ctx->refile_seq, seq));
+ } while (read_seqretry(&ctx->refile_seq, seq));
if (need_wakeup)
__wake_userfault(ctx, range);
}
@@ -1915,7 +1915,7 @@ static void init_once_userfaultfd_ctx(void *mem)
init_waitqueue_head(&ctx->fault_wqh);
init_waitqueue_head(&ctx->event_wqh);
init_waitqueue_head(&ctx->fd_wqh);
- seqcount_init(&ctx->refile_seq);
+ seqlock_init(&ctx->refile_seq);
}

/**
diff --git a/include/linux/locallock.h b/include/linux/locallock.h
index 921eab83cd34a..81c89d87723b5 100644
--- a/include/linux/locallock.h
+++ b/include/linux/locallock.h
@@ -3,6 +3,7 @@

#include <linux/percpu.h>
#include <linux/spinlock.h>
+#include <asm/current.h>

#ifdef CONFIG_PREEMPT_RT_BASE

diff --git a/include/linux/trace_events.h b/include/linux/trace_events.h
index edd1e42e8a2f7..01e9ab3107531 100644
--- a/include/linux/trace_events.h
+++ b/include/linux/trace_events.h
@@ -62,8 +62,7 @@ struct trace_entry {
unsigned char flags;
unsigned char preempt_count;
int pid;
- unsigned short migrate_disable;
- unsigned short padding;
+ unsigned char migrate_disable;
unsigned char preempt_lazy_count;
};

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index f30bb249123b5..3ff48df25cff8 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -6964,6 +6964,9 @@ static void migrate_disabled_sched(struct task_struct *p)
p->migrate_disable_scheduled = 1;
}

+static DEFINE_PER_CPU(struct cpu_stop_work, migrate_work);
+static DEFINE_PER_CPU(struct migration_arg, migrate_arg);
+
void migrate_enable(void)
{
struct task_struct *p = current;
@@ -7002,23 +7005,25 @@ void migrate_enable(void)

WARN_ON(smp_processor_id() != cpu);
if (!is_cpu_allowed(p, cpu)) {
- struct migration_arg arg = { .task = p };
- struct cpu_stop_work work;
+ struct migration_arg __percpu *arg;
+ struct cpu_stop_work __percpu *work;
struct rq_flags rf;

+ work = this_cpu_ptr(&migrate_work);
+ arg = this_cpu_ptr(&migrate_arg);
+ WARN_ON_ONCE(!arg->done && !work->disabled && work->arg);
+
+ arg->task = p;
+ arg->done = false;
+
rq = task_rq_lock(p, &rf);
update_rq_clock(rq);
- arg.dest_cpu = select_fallback_rq(cpu, p);
+ arg->dest_cpu = select_fallback_rq(cpu, p);
task_rq_unlock(rq, p, &rf);

stop_one_cpu_nowait(task_cpu(p), migration_cpu_stop,
- &arg, &work);
+ arg, work);
tlb_migrate_finish(p->mm);
- __schedule(true);
- if (!work.disabled) {
- while (!arg.done)
- cpu_relax();
- }
}

out:
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 60e371451ec31..edd43841c94ad 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -187,8 +187,8 @@ static int trace_define_common_fields(void)
__common_field(unsigned char, flags);
__common_field(unsigned char, preempt_count);
__common_field(int, pid);
- __common_field(unsigned short, migrate_disable);
- __common_field(unsigned short, padding);
+ __common_field(unsigned char, migrate_disable);
+ __common_field(unsigned char, preempt_lazy_count);

return ret;
}
diff --git a/localversion-rt b/localversion-rt
index 595841feef807..30758e0b2242b 100644
--- a/localversion-rt
+++ b/localversion-rt
@@ -1 +1 @@
--rt77
+-rt78
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 0503b31e2a873..a359a24ebd9f0 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -6102,10 +6102,10 @@ void mem_cgroup_swapout(struct page *page, swp_entry_t entry)
mem_cgroup_charge_statistics(memcg, page, PageTransHuge(page),
-nr_entries);
memcg_check_events(memcg, page);
+ local_unlock_irqrestore(event_lock, flags);

if (!mem_cgroup_is_root(memcg))
css_put_many(&memcg->css, nr_entries);
- local_unlock_irqrestore(event_lock, flags);
}

/**

Next message: Joel Fernandes (Google): "[PATCH v2 rcu-dev 1/3] rcuperf: Add ability to increase object allocation size"
Previous message: Josh Poimboeuf: "Re: [RFC][PATCH 15/16] objtool: Implement noinstr validation"
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