[S390] fix list corruption in gmap reverse mapping
This introduces locking via mm->page_table_lock to protect
the rmap list for guest mappings from being corrupted by concurrent
operations.
Signed-off-by: Carsten Otte <cotte@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/arch/s390/mm/pgtable.c b/arch/s390/mm/pgtable.c
index e4a4cef..96e85ac 100644
--- a/arch/s390/mm/pgtable.c
+++ b/arch/s390/mm/pgtable.c
@@ -222,6 +222,7 @@
/* Free all segment & region tables. */
down_read(&gmap->mm->mmap_sem);
+ spin_lock(&gmap->mm->page_table_lock);
list_for_each_entry_safe(page, next, &gmap->crst_list, lru) {
table = (unsigned long *) page_to_phys(page);
if ((*table & _REGION_ENTRY_TYPE_MASK) == 0)
@@ -230,6 +231,7 @@
gmap_unlink_segment(gmap, table);
__free_pages(page, ALLOC_ORDER);
}
+ spin_unlock(&gmap->mm->page_table_lock);
up_read(&gmap->mm->mmap_sem);
list_del(&gmap->list);
kfree(gmap);
@@ -300,6 +302,7 @@
flush = 0;
down_read(&gmap->mm->mmap_sem);
+ spin_lock(&gmap->mm->page_table_lock);
for (off = 0; off < len; off += PMD_SIZE) {
/* Walk the guest addr space page table */
table = gmap->table + (((to + off) >> 53) & 0x7ff);
@@ -321,6 +324,7 @@
*table = _SEGMENT_ENTRY_INV;
}
out:
+ spin_unlock(&gmap->mm->page_table_lock);
up_read(&gmap->mm->mmap_sem);
if (flush)
gmap_flush_tlb(gmap);
@@ -351,6 +355,7 @@
flush = 0;
down_read(&gmap->mm->mmap_sem);
+ spin_lock(&gmap->mm->page_table_lock);
for (off = 0; off < len; off += PMD_SIZE) {
/* Walk the gmap address space page table */
table = gmap->table + (((to + off) >> 53) & 0x7ff);
@@ -374,12 +379,14 @@
flush |= gmap_unlink_segment(gmap, table);
*table = _SEGMENT_ENTRY_INV | _SEGMENT_ENTRY_RO | (from + off);
}
+ spin_unlock(&gmap->mm->page_table_lock);
up_read(&gmap->mm->mmap_sem);
if (flush)
gmap_flush_tlb(gmap);
return 0;
out_unmap:
+ spin_unlock(&gmap->mm->page_table_lock);
up_read(&gmap->mm->mmap_sem);
gmap_unmap_segment(gmap, to, len);
return -ENOMEM;
@@ -446,7 +453,9 @@
page = pmd_page(*pmd);
mp = (struct gmap_pgtable *) page->index;
rmap->entry = table;
+ spin_lock(&mm->page_table_lock);
list_add(&rmap->list, &mp->mapper);
+ spin_unlock(&mm->page_table_lock);
/* Set gmap segment table entry to page table. */
*table = pmd_val(*pmd) & PAGE_MASK;
return vmaddr | (address & ~PMD_MASK);