Setting vm_dirty_bytes and dirty_background_bytes is not protected by any
serialization.
Therefore, it's possible for either variable to change value after the
test in global_dirty_limits() to determine whether available_memory needs
to be initialized or not.
Always ensure that available_memory is properly initialized.
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: David Rientjes <rientjes@xxxxxxxxxx>
---
mm/page-writeback.c | 5 +----
1 file changed, 1 insertion(+), 4 deletions(-)
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -261,14 +261,11 @@ static unsigned long global_dirtyable_memory(void)
*/
void global_dirty_limits(unsigned long *pbackground, unsigned long *pdirty)
{
+ const unsigned long available_memory = global_dirtyable_memory();
unsigned long background;
unsigned long dirty;
- unsigned long uninitialized_var(available_memory);
struct task_struct *tsk;
- if (!vm_dirty_bytes || !dirty_background_bytes)
- available_memory = global_dirtyable_memory();
-
if (vm_dirty_bytes)
dirty = DIV_ROUND_UP(vm_dirty_bytes, PAGE_SIZE);
else
--
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