Blackfin: fix up mm locking in address dumping
The locking code in the address dumper needs to grab the mm's mmap_sem
so that other CPUs do not get an inconsistent view. On UP systems this
really wasn't a problem, but it is easy to trigger a race on SMP systems
when another CPU removes a mapping.
Signed-off-by: Graf Yang <graf.yang@analog.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
diff --git a/arch/blackfin/kernel/traps.c b/arch/blackfin/kernel/traps.c
index 870d74b..8576680 100644
--- a/arch/blackfin/kernel/traps.c
+++ b/arch/blackfin/kernel/traps.c
@@ -138,6 +138,12 @@
if (!mm)
continue;
+ if (!down_read_trylock(&mm->mmap_sem)) {
+ if (!in_atomic)
+ mmput(mm);
+ continue;
+ }
+
for (n = rb_first(&mm->mm_rb); n; n = rb_next(n)) {
struct vm_area_struct *vma;
@@ -177,6 +183,7 @@
sprintf(buf, "[ %s vma:0x%lx-0x%lx]",
name, vma->vm_start, vma->vm_end);
+ up_read(&mm->mmap_sem);
if (!in_atomic)
mmput(mm);
@@ -186,11 +193,16 @@
goto done;
}
}
+
+ up_read(&mm->mmap_sem);
if (!in_atomic)
mmput(mm);
}
- /* we were unable to find this address anywhere */
+ /*
+ * we were unable to find this address anywhere,
+ * or some MMs were skipped because they were in use.
+ */
sprintf(buf, "/* kernel dynamic memory */");
done: