Patch "sched/preempt, sh: kmap_coherent relies on disabled preemption" has been added to the 4.4-stable tree

[<gregkh@linuxfoundation.org>]

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

    sched/preempt, sh: kmap_coherent relies on disabled preemption

to the 4.4-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:
     sched-preempt-sh-kmap_coherent-relies-on-disabled-preemption.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From b15d53d009558d14c4f394a6d1fa2039c7f45c43 Mon Sep 17 00:00:00 2001
From: David Hildenbrand <dahi@linux.vnet.ibm.com>
Date: Mon, 29 Feb 2016 09:19:24 +0100
Subject: sched/preempt, sh: kmap_coherent relies on disabled preemption

From: David Hildenbrand <dahi@linux.vnet.ibm.com>

commit b15d53d009558d14c4f394a6d1fa2039c7f45c43 upstream.

kmap_coherent needs disabled preemption to not schedule in the critical
section, just like kmap_coherent on mips and kmap_atomic in general.

Fixes: 8222dbe21e79 "sched/preempt, mm/fault: Decouple preemption from the page fault logic"
Reported-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: David Hildenbrand <dahi@linux.vnet.ibm.com>
Tested-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Rich Felker <dalias@libc.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 arch/sh/mm/kmap.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/arch/sh/mm/kmap.c
+++ b/arch/sh/mm/kmap.c
@@ -36,6 +36,7 @@ void *kmap_coherent(struct page *page, u
 
 	BUG_ON(!test_bit(PG_dcache_clean, &page->flags));
 
+	preempt_disable();
 	pagefault_disable();
 
 	idx = FIX_CMAP_END -
@@ -64,4 +65,5 @@ void kunmap_coherent(void *kvaddr)
 	}
 
 	pagefault_enable();
+	preempt_enable();
 }


Patches currently in stable-queue which might be from dahi@linux.vnet.ibm.com are

queue-4.4/sched-preempt-sh-kmap_coherent-relies-on-disabled-preemption.patch