This is a note to let you know that I've just added the patch titled
KVM: s390/mm: Fix page table locking vs. split pmd lock
to the 3.16-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:
kvm-s390-mm-fix-page-table-locking-vs.-split-pmd-lock.patch
and it can be found in the queue-3.16 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 55e4283c3eb1d850893f645dd695c9c75d5fa1fc Mon Sep 17 00:00:00 2001
From: Christian Borntraeger <borntraeger@xxxxxxxxxx>
Date: Fri, 25 Jul 2014 14:23:29 +0200
Subject: KVM: s390/mm: Fix page table locking vs. split pmd lock
From: Christian Borntraeger <borntraeger@xxxxxxxxxx>
commit 55e4283c3eb1d850893f645dd695c9c75d5fa1fc upstream.
commit ec66ad66a0de87866be347b5ecc83bd46427f53b (s390/mm: enable
split page table lock for PMD level) activated the split pmd lock
for s390. Turns out that we missed one place: We also have to take
the pmd lock instead of the page table lock when we reallocate the
page tables (==> changing entries in the PMD) during sie enablement.
Signed-off-by: Christian Borntraeger <borntraeger@xxxxxxxxxx>
Signed-off-by: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/s390/mm/pgtable.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
--- a/arch/s390/mm/pgtable.c
+++ b/arch/s390/mm/pgtable.c
@@ -1279,6 +1279,7 @@ static unsigned long page_table_realloc_
{
unsigned long next, *table, *new;
struct page *page;
+ spinlock_t *ptl;
pmd_t *pmd;
pmd = pmd_offset(pud, addr);
@@ -1296,7 +1297,7 @@ again:
if (!new)
return -ENOMEM;
- spin_lock(&mm->page_table_lock);
+ ptl = pmd_lock(mm, pmd);
if (likely((unsigned long *) pmd_deref(*pmd) == table)) {
/* Nuke pmd entry pointing to the "short" page table */
pmdp_flush_lazy(mm, addr, pmd);
@@ -1310,7 +1311,7 @@ again:
page_table_free_rcu(tlb, table);
new = NULL;
}
- spin_unlock(&mm->page_table_lock);
+ spin_unlock(ptl);
if (new) {
page_table_free_pgste(new);
goto again;
Patches currently in stable-queue which might be from borntraeger@xxxxxxxxxx are
queue-3.16/kvm-s390-mm-fix-page-table-locking-vs.-split-pmd-lock.patch
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