Patch "genirq: Prevent resend to interrupts marked IRQ_NESTED_THREAD" has been added to the 4.1-stable tree

This is a note to let you know that I've just added the patch titled

    genirq: Prevent resend to interrupts marked IRQ_NESTED_THREAD

to the 4.1-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     genirq-prevent-resend-to-interrupts-marked-irq_nested_thread.patch
and it can be found in the queue-4.1 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let [off-list ref] know about it.

From 75a06189fc508a2acf470b0b12710362ffb2c4b1 Mon Sep 17 00:00:00 2001

From: Thomas Gleixner <redacted>
Date: Thu, 16 Jul 2015 14:10:17 +0200
Subject: genirq: Prevent resend to interrupts marked IRQ_NESTED_THREAD
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

From: Thomas Gleixner <redacted>

commit 75a06189fc508a2acf470b0b12710362ffb2c4b1 upstream.

The resend mechanism happily calls the interrupt handler of interrupts
which are marked IRQ_NESTED_THREAD from softirq context. This can
result in crashes because the interrupt handler is not the proper way
to invoke the device handlers. They must be invoked via
handle_nested_irq.

Prevent the resend even if the interrupt has no valid parent irq
set. Its better to have a lost interrupt than a crashing machine.

Reported-by: Uwe Kleine-König <redacted>
Signed-off-by: Thomas Gleixner <redacted>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 kernel/irq/resend.c |   18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

--- a/kernel/irq/resend.c
+++ b/kernel/irq/resend.c

@@ -75,13 +75,21 @@ void check_irq_resend(struct irq_desc *d
 		    !desc->irq_data.chip->irq_retrigger(&desc->irq_data)) {
 #ifdef CONFIG_HARDIRQS_SW_RESEND
 			/*
-			 * If the interrupt has a parent irq and runs
-			 * in the thread context of the parent irq,
-			 * retrigger the parent.
+			 * If the interrupt is running in the thread
+			 * context of the parent irq we need to be
+			 * careful, because we cannot trigger it
+			 * directly.
 			 */
-			if (desc->parent_irq &&
-			    irq_settings_is_nested_thread(desc))
+			if (irq_settings_is_nested_thread(desc)) {
+				/*
+				 * If the parent_irq is valid, we
+				 * retrigger the parent, otherwise we
+				 * do nothing.
+				 */
+				if (!desc->parent_irq)
+					return;
 				irq = desc->parent_irq;
+			}
 			/* Set it pending and activate the softirq: */
 			set_bit(irq, irqs_resend);
 			tasklet_schedule(&resend_tasklet);

Patches currently in stable-queue which might be from tglx@linutronix.de are

queue-4.1/x86-kasan-fix-kasan-shadow-region-page-tables.patch
queue-4.1/x86-kasan-fix-boot-crash-on-amd-processors.patch
queue-4.1/genirq-prevent-resend-to-interrupts-marked-irq_nested_thread.patch
queue-4.1/x86-init-clear-init_level4_pgt-earlier.patch
queue-4.1/x86-kasan-flush-tlbs-after-switching-cr3.patch