We need to make sure slots are protected on reading a handle. Since
handles are modified by free_handle() which only takes slot rwlock,
that lock should be used when handles are read.
Signed-off-by: Vitaly Wool <vitaly.vul@xxxxxxxx>
---
mm/z3fold.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/mm/z3fold.c b/mm/z3fold.c
index f2a75418e248..43754d8ebce8 100644
--- a/mm/z3fold.c
+++ b/mm/z3fold.c
@@ -486,8 +486,12 @@ static unsigned long encode_handle(struct z3fold_header *zhdr, enum buddy bud)
/* only for LAST bud, returns zero otherwise */
static unsigned short handle_to_chunks(unsigned long handle)
{
- unsigned long addr = *(unsigned long *)handle;
+ struct z3fold_buddy_slots *slots = handle_to_slots(handle);
+ unsigned long addr;
+ read_lock(&slots->lock);
+ addr = *(unsigned long *)handle;
+ read_unlock(&slots->lock);
return (addr & ~PAGE_MASK) >> BUDDY_SHIFT;
}
@@ -499,10 +503,13 @@ static unsigned short handle_to_chunks(unsigned long handle)
static enum buddy handle_to_buddy(unsigned long handle)
{
struct z3fold_header *zhdr;
+ struct z3fold_buddy_slots *slots = handle_to_slots(handle);
unsigned long addr;
+ read_lock(&slots->lock);
WARN_ON(handle & (1 << PAGE_HEADLESS));
addr = *(unsigned long *)handle;
+ read_unlock(&slots->lock);
zhdr = (struct z3fold_header *)(addr & PAGE_MASK);
return (addr - zhdr->first_num) & BUDDY_MASK;
}
--
2.17.1
