[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>

1 files changed, 9 insertions, 0 deletions

diff --git a/arch/s390/mm/pgtable.c b/arch/s390/mm/pgtable.c
index e4a4cefb92b3..96e85ac89269 100644
--- a/arch/s390/mm/pgtable.c
+++ b/arch/s390/mm/pgtable.c
@@ -222,6 +222,7 @@ void gmap_free(struct gmap *gmap)
 
         /* 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 @@ void gmap_free(struct gmap *gmap)
                                 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 @@ int gmap_unmap_segment(struct gmap *gmap, unsigned long to, unsigned long len)
 
         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 @@ int gmap_unmap_segment(struct gmap *gmap, unsigned long to, unsigned long len)
                 *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 @@ int gmap_map_segment(struct gmap *gmap, unsigned long from,
 
         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 @@ int gmap_map_segment(struct gmap *gmap, unsigned long from,
                 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 @@ unsigned long gmap_fault(unsigned long address, struct gmap *gmap)
                 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);