The GHES code calls memory_failure_queue() from IRQ context to queue work
into workqueue and schedule it on the current CPU. Then the work is
processed in memory_failure_work_func() by kworker and calls
memory_failure().
When a page is already poisoned, commit a3f5d80ea401 ("mm,hwpoison: send
SIGBUS with error virutal address") make memory_failure() call
kill_accessing_process() that:
- holds mmap locking of current->mm
- does pagetable walk to find the error virtual address
- and sends SIGBUS to the current process with error info.
However, the mm of kworker is not valid. Therefore, check mm when killing
accessing process.
Fixes: a3f5d80ea401 ("mm,hwpoison: send SIGBUS with error virutal address")
Signed-off-by: Shuai Xue <xueshuai@xxxxxxxxxxxxxxxxx>
---
mm/memory-failure.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 14439806b5ef..7553917ce820 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -743,6 +743,9 @@ static int kill_accessing_process(struct task_struct *p, unsigned long pfn,
};
priv.tk.tsk = p;
+ if (!p->mm)
+ return -EFAULT;
+
mmap_read_lock(p->mm);
ret = walk_page_range(p->mm, 0, TASK_SIZE, &hwp_walk_ops,
(void *)&priv);
@@ -751,6 +754,7 @@ static int kill_accessing_process(struct task_struct *p, unsigned long pfn,
else
ret = 0;
mmap_read_unlock(p->mm);
+
return ret > 0 ? -EHWPOISON : -EFAULT;
}
--
2.20.1.12.g72788fdb
