Dear RT folks!
I'm pleased to announce the v5.9-rc3-rt3 patch set.
Changes since v5.9-rc3-rt2:
- Correct a compile issue in the i915 driver. Reported by Carsten Emde
and Daniel Wagner.
- Mark Marshall reported a crash on PowerPC. The reason for the crash
is a race in exec_mmap() vs a context switch and is not limited to
PowerPC. This race is present since v5.4.3-rt1 and is addressed in
two changes:
- commit 38cf307c1f201 ("mm: fix kthread_use_mm() vs TLB invalidate")
which is part of v5.9-rc1.
- patch "mm: fix exec activate_mm vs TLB shootdown and lazy tlb switching race"
by Nicholas Piggin which has been posted for review and is not yet
merged upstream.
Known issues
- It has been pointed out that due to changes to the printk code the
internal buffer representation changed. This is only an issue if tools
like `crash' are used to extract the printk buffer from a kernel memory
image.
The delta patch against v5.9-rc3-rt2 is appended below and can be found here:
https://cdn.kernel.org/pub/linux/kernel/projects/rt/5.9/incr/patch-5.9-rc3-rt2-rt3.patch.xz
You can get this release via the git tree at:
git://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git v5.9-rc3-rt3
The RT patch against v5.9-rc3 can be found here:
https://cdn.kernel.org/pub/linux/kernel/projects/rt/5.9/older/patch-5.9-rc3-rt3.patch.xz
The split quilt queue is available at:
https://cdn.kernel.org/pub/linux/kernel/projects/rt/5.9/older/patches-5.9-rc3-rt3.tar.xz
Sebastian
diff --git a/arch/Kconfig b/arch/Kconfig
index 222e553f3cf50..5c8e173dc7c2b 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -415,6 +415,13 @@ config MMU_GATHER_NO_GATHER
bool
depends on MMU_GATHER_TABLE_FREE
+config ARCH_WANT_IRQS_OFF_ACTIVATE_MM
+ bool
+ help
+ Temporary select until all architectures can be converted to have
+ irqs disabled over activate_mm. Architectures that do IPI based TLB
+ shootdowns should enable this.
+
config ARCH_HAVE_NMI_SAFE_CMPXCHG
bool
diff --git a/drivers/gpu/drm/i915/display/intel_display_types.h b/drivers/gpu/drm/i915/display/intel_display_types.h
index c5700f44422ec..e8f809161c75f 100644
--- a/drivers/gpu/drm/i915/display/intel_display_types.h
+++ b/drivers/gpu/drm/i915/display/intel_display_types.h
@@ -29,7 +29,6 @@
#include <linux/async.h>
#include <linux/i2c.h>
#include <linux/sched/clock.h>
-#include <linux/local_lock.h>
#include <drm/drm_atomic.h>
#include <drm/drm_crtc.h>
@@ -1150,7 +1149,6 @@ struct intel_crtc {
#ifdef CONFIG_DEBUG_FS
struct intel_pipe_crc pipe_crc;
#endif
- local_lock_t pipe_update_lock;
};
struct intel_plane {
diff --git a/drivers/gpu/drm/i915/display/intel_sprite.c b/drivers/gpu/drm/i915/display/intel_sprite.c
index 62b8248d2ee79..1b9d5e690a9f0 100644
--- a/drivers/gpu/drm/i915/display/intel_sprite.c
+++ b/drivers/gpu/drm/i915/display/intel_sprite.c
@@ -118,7 +118,8 @@ void intel_pipe_update_start(const struct intel_crtc_state *new_crtc_state)
"PSR idle timed out 0x%x, atomic update may fail\n",
psr_status);
- local_lock_irq(&crtc->pipe_update_lock);
+ if (!IS_ENABLED(CONFIG_PREEMPT_RT))
+ local_irq_disable();
crtc->debug.min_vbl = min;
crtc->debug.max_vbl = max;
@@ -143,11 +144,13 @@ void intel_pipe_update_start(const struct intel_crtc_state *new_crtc_state)
break;
}
- local_unlock_irq(&crtc->pipe_update_lock);
+ if (!IS_ENABLED(CONFIG_PREEMPT_RT))
+ local_irq_enable();
timeout = schedule_timeout(timeout);
- local_lock_irq(&crtc->pipe_update_lock);
+ if (!IS_ENABLED(CONFIG_PREEMPT_RT))
+ local_irq_disable();
}
finish_wait(wq, &wait);
@@ -180,7 +183,8 @@ void intel_pipe_update_start(const struct intel_crtc_state *new_crtc_state)
return;
irq_disable:
- local_lock_irq(&crtc->pipe_update_lock);
+ if (!IS_ENABLED(CONFIG_PREEMPT_RT))
+ local_irq_disable();
}
/**
@@ -218,7 +222,8 @@ void intel_pipe_update_end(struct intel_crtc_state *new_crtc_state)
new_crtc_state->uapi.event = NULL;
}
- local_unlock_irq(&crtc->pipe_update_lock);
+ if (!IS_ENABLED(CONFIG_PREEMPT_RT))
+ local_irq_enable();
if (intel_vgpu_active(dev_priv))
return;
diff --git a/fs/exec.c b/fs/exec.c
index a91003e28eaae..d4fb18baf1fb1 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -1130,11 +1130,24 @@ static int exec_mmap(struct mm_struct *mm)
}
task_lock(tsk);
- active_mm = tsk->active_mm;
membarrier_exec_mmap(mm);
- tsk->mm = mm;
+
+ local_irq_disable();
+ active_mm = tsk->active_mm;
tsk->active_mm = mm;
+ tsk->mm = mm;
+ /*
+ * This prevents preemption while active_mm is being loaded and
+ * it and mm are being updated, which could cause problems for
+ * lazy tlb mm refcounting when these are updated by context
+ * switches. Not all architectures can handle irqs off over
+ * activate_mm yet.
+ */
+ if (!IS_ENABLED(CONFIG_ARCH_WANT_IRQS_OFF_ACTIVATE_MM))
+ local_irq_enable();
activate_mm(active_mm, mm);
+ if (IS_ENABLED(CONFIG_ARCH_WANT_IRQS_OFF_ACTIVATE_MM))
+ local_irq_enable();
tsk->mm->vmacache_seqnum = 0;
vmacache_flush(tsk);
task_unlock(tsk);
diff --git a/localversion-rt b/localversion-rt
index c3054d08a1129..1445cd65885cd 100644
--- a/localversion-rt
+++ b/localversion-rt
@@ -1 +1 @@
--rt2
+-rt3
