Hello RT Folks!
I'm pleased to announce the 5.4.182-rt71 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: v5.4-rt
Head SHA1: 8f83fc7941f704f55939adaa778afd8ae76662e4
Or to build 5.4.182-rt71 directly, the following patches should be applied:
https://www.kernel.org/pub/linux/kernel/v5.x/linux-5.4.tar.xz
https://www.kernel.org/pub/linux/kernel/v5.x/patch-5.4.182.xz
https://www.kernel.org/pub/linux/kernel/projects/rt/5.4/patch-5.4.182-rt71.patch.xz
You can also build from 5.4.182-rt70 by applying the incremental patch:
https://www.kernel.org/pub/linux/kernel/projects/rt/5.4/incr/patch-5.4.182-rt70-rt71.patch.xz
Enjoy!
Tom
Changes from v5.4.182-rt70:
---
Thomas Gleixner (1):
eventfd: Make signal recursion protection a task bit
Tom Zanussi (1):
Linux 5.4.182-rt71
Xie Yongji (1):
aio: Fix incorrect usage of eventfd_signal_allowed()
---
fs/aio.c | 2 +-
fs/eventfd.c | 12 +++++-------
include/linux/eventfd.h | 11 +++++------
include/linux/sched.h | 12 ++++++++++++
localversion-rt | 2 +-
5 files changed, 24 insertions(+), 15 deletions(-)
---
diff --git a/fs/aio.c b/fs/aio.c
index fb92c32a6f1e..0bb9abf39065 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -1767,7 +1767,7 @@ static int aio_poll_wake(struct wait_queue_entry *wait, unsigned mode, int sync,
list_del_init(&req->wait.entry);
list_del(&iocb->ki_list);
iocb->ki_res.res = mangle_poll(mask);
- if (iocb->ki_eventfd && eventfd_signal_count()) {
+ if (iocb->ki_eventfd && !eventfd_signal_allowed()) {
iocb = NULL;
INIT_WORK(&req->work, aio_poll_put_work);
schedule_work(&req->work);
diff --git a/fs/eventfd.c b/fs/eventfd.c
index 78e41c7c3d05..661ccc45852b 100644
--- a/fs/eventfd.c
+++ b/fs/eventfd.c
@@ -24,8 +24,6 @@
#include <linux/seq_file.h>
#include <linux/idr.h>
-DEFINE_PER_CPU(int, eventfd_wake_count);
-
static DEFINE_IDA(eventfd_ida);
struct eventfd_ctx {
@@ -66,21 +64,21 @@ __u64 eventfd_signal(struct eventfd_ctx *ctx, __u64 n)
* Deadlock or stack overflow issues can happen if we recurse here
* through waitqueue wakeup handlers. If the caller users potentially
* nested waitqueues with custom wakeup handlers, then it should
- * check eventfd_signal_count() before calling this function. If
- * it returns true, the eventfd_signal() call should be deferred to a
+ * check eventfd_signal_allowed() before calling this function. If
+ * it returns false, the eventfd_signal() call should be deferred to a
* safe context.
*/
- if (WARN_ON_ONCE(this_cpu_read(eventfd_wake_count)))
+ if (WARN_ON_ONCE(current->in_eventfd_signal))
return 0;
spin_lock_irqsave(&ctx->wqh.lock, flags);
- this_cpu_inc(eventfd_wake_count);
+ current->in_eventfd_signal = 1;
if (ULLONG_MAX - ctx->count < n)
n = ULLONG_MAX - ctx->count;
ctx->count += n;
if (waitqueue_active(&ctx->wqh))
wake_up_locked_poll(&ctx->wqh, EPOLLIN);
- this_cpu_dec(eventfd_wake_count);
+ current->in_eventfd_signal = 0;
spin_unlock_irqrestore(&ctx->wqh.lock, flags);
return n;
diff --git a/include/linux/eventfd.h b/include/linux/eventfd.h
index dc4fd8a6644d..836b4c021a0a 100644
--- a/include/linux/eventfd.h
+++ b/include/linux/eventfd.h
@@ -14,6 +14,7 @@
#include <linux/err.h>
#include <linux/percpu-defs.h>
#include <linux/percpu.h>
+#include <linux/sched.h>
/*
* CAREFUL: Check include/uapi/asm-generic/fcntl.h when defining
@@ -42,11 +43,9 @@ __u64 eventfd_signal(struct eventfd_ctx *ctx, __u64 n);
int eventfd_ctx_remove_wait_queue(struct eventfd_ctx *ctx, wait_queue_entry_t *wait,
__u64 *cnt);
-DECLARE_PER_CPU(int, eventfd_wake_count);
-
-static inline bool eventfd_signal_count(void)
+static inline bool eventfd_signal_allowed(void)
{
- return this_cpu_read(eventfd_wake_count);
+ return !current->in_eventfd_signal;
}
#else /* CONFIG_EVENTFD */
@@ -77,9 +76,9 @@ static inline int eventfd_ctx_remove_wait_queue(struct eventfd_ctx *ctx,
return -ENOSYS;
}
-static inline bool eventfd_signal_count(void)
+static inline bool eventfd_signal_allowed(void)
{
- return false;
+ return true;
}
#endif
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 79e34e98f812..e1dfb01f4623 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -802,6 +802,18 @@ struct task_struct {
/* to be used once the psi infrastructure lands upstream. */
unsigned use_memdelay:1;
#endif
+#ifdef CONFIG_PSI
+ /* Stalled due to lack of memory */
+ unsigned in_memstall:1;
+#endif
+#ifdef CONFIG_PAGE_OWNER
+ /* Used by page_owner=on to detect recursion in page tracking. */
+ unsigned in_page_owner:1;
+#endif
+#ifdef CONFIG_EVENTFD
+ /* Recursion prevention for eventfd_signal() */
+ unsigned in_eventfd_signal:1;
+#endif
unsigned long atomic_flags; /* Flags requiring atomic access. */
diff --git a/localversion-rt b/localversion-rt
index f36b5d418dd8..f38a3cc7f310 100644
--- a/localversion-rt
+++ b/localversion-rt
@@ -1 +1 @@
--rt70
+-rt71
On 2022-03-11 15:46:23 [-0600], Tom Zanussi wrote:
> index 79e34e98f812..e1dfb01f4623 100644
> --- a/include/linux/sched.h
> +++ b/include/linux/sched.h
> @@ -802,6 +802,18 @@ struct task_struct {
> /* to be used once the psi infrastructure lands upstream. */
> unsigned use_memdelay:1;
> #endif
> +#ifdef CONFIG_PSI
> + /* Stalled due to lack of memory */
> + unsigned in_memstall:1;
> +#endif
> +#ifdef CONFIG_PAGE_OWNER
> + /* Used by page_owner=on to detect recursion in page tracking. */
> + unsigned in_page_owner:1;
> +#endif
the upper two don't look like they belong here.
> +#ifdef CONFIG_EVENTFD
> + /* Recursion prevention for eventfd_signal() */
> + unsigned in_eventfd_signal:1;
> +#endif
>
> unsigned long atomic_flags; /* Flags requiring atomic access. */
>
> diff --git a/localversion-rt b/localversion-rt
Sebastian
On Fri, 2022-03-11 at 23:09 +0100, Sebastian Andrzej Siewior wrote:
> On 2022-03-11 15:46:23 [-0600], Tom Zanussi wrote:
> > index 79e34e98f812..e1dfb01f4623 100644
> > --- a/include/linux/sched.h
> > +++ b/include/linux/sched.h
> > @@ -802,6 +802,18 @@ struct task_struct {
> > /* to be used once the psi infrastructure lands upstream. */
> > unsigned use_memdelay:1;
> > #endif
> > +#ifdef CONFIG_PSI
> > + /* Stalled due to lack of memory */
> > + unsigned in_memstall:1;
> > +#endif
> > +#ifdef CONFIG_PAGE_OWNER
> > + /* Used by page_owner=on to detect recursion in page tracking.
> > */
> > + unsigned in_page_owner:1;
> > +#endif
>
> the upper two don't look like they belong here.
You're right, they don't - I missed those when fixing the conflict in
this file. Will do a new release shortly to fix that.
Thanks for reviewing and pointing it out.
Tom
>
> > +#ifdef CONFIG_EVENTFD
> > + /* Recursion prevention for eventfd_signal() */
> > + unsigned in_eventfd_signal:1;
> > +#endif
> >
> > unsigned long atomic_flags; /* Flags
> > requiring atomic access. */
> >
> > diff --git a/localversion-rt b/localversion-rt
>
> Sebastian