Currently, the mem_dump_obj() is invoked in call_rcu(), the
call_rcu() is maybe invoked in non-preemptive code segment,
for object allocated from vmalloc(), the following scenarios
may occur:
CPU 0
tasks context
spin_lock(&vmap_area_lock)
Interrupt context
call_rcu()
mem_dump_obj
vmalloc_dump_obj
spin_lock(&vmap_area_lock) <--deadlock
and for PREEMPT-RT kernel, the spinlock will convert to sleepable
lock, it also make vmap_area_lock spinlock can not acquire in
non-preemptive code segment. therefore, this commit make the
vmalloc_dump_obj() call in a preemptible context.
Signed-off-by: Zqiang <qiang1.zhang@xxxxxxxxx>
---
mm/util.c | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)
diff --git a/mm/util.c b/mm/util.c
index 12984e76767e..465f8b8824ca 100644
--- a/mm/util.c
+++ b/mm/util.c
@@ -1124,8 +1124,12 @@ void mem_dump_obj(void *object)
return;
}
- if (vmalloc_dump_obj(object))
- return;
+ if (is_vmalloc_addr(object)) {
+ if (preemptible() && vmalloc_dump_obj(object))
+ return;
+ type = "vmalloc memory";
+ goto end;
+ }
if (virt_addr_valid(object))
type = "non-slab/vmalloc memory";
@@ -1135,7 +1139,7 @@ void mem_dump_obj(void *object)
type = "zero-size pointer";
else
type = "non-paged memory";
-
+end:
pr_cont(" %s\n", type);
}
EXPORT_SYMBOL_GPL(mem_dump_obj);
--
2.25.1
