It is unsafe to dump vmalloc area information when trying to do so from
some contexts. Add a safer trylock version of the same function to do a
best-effort VMA finding and use it from vmalloc_dump_obj().
[applied test robot feedback on unused function fix.]
[applied Uladzislau feedback on locking.]
Reported-by: Zhen Lei <thunder.leizhen@xxxxxxxxxxxxxxx>
Cc: Paul E. McKenney <paulmck@xxxxxxxxxx>
Cc: rcu@xxxxxxxxxxxxxxx
Cc: Zqiang <qiang.zhang1211@xxxxxxxxx>
Reviewed-by: Uladzislau Rezki (Sony) <urezki@xxxxxxxxx>
Fixes: 98f180837a89 ("mm: Make mem_dump_obj() handle vmalloc() memory")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Joel Fernandes (Google) <joel@xxxxxxxxxxxxxxxxx>
---
mm/vmalloc.c | 26 ++++++++++++++++++++++----
1 file changed, 22 insertions(+), 4 deletions(-)
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 93cf99aba335..2c6a0e2ff404 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -4274,14 +4274,32 @@ void pcpu_free_vm_areas(struct vm_struct **vms, int nr_vms)
#ifdef CONFIG_PRINTK
bool vmalloc_dump_obj(void *object)
{
- struct vm_struct *vm;
void *objp = (void *)PAGE_ALIGN((unsigned long)object);
+ const void *caller;
+ struct vm_struct *vm;
+ struct vmap_area *va;
+ unsigned long addr;
+ unsigned int nr_pages;
- vm = find_vm_area(objp);
- if (!vm)
+ if (!spin_trylock(&vmap_area_lock))
+ return false;
+ va = __find_vmap_area((unsigned long)objp, &vmap_area_root);
+ if (!va) {
+ spin_unlock(&vmap_area_lock);
return false;
+ }
+
+ vm = va->vm;
+ if (!vm) {
+ spin_unlock(&vmap_area_lock);
+ return false;
+ }
+ addr = (unsigned long)vm->addr;
+ caller = vm->caller;
+ nr_pages = vm->nr_pages;
+ spin_unlock(&vmap_area_lock);
pr_cont(" %u-page vmalloc region starting at %#lx allocated at %pS\n",
- vm->nr_pages, (unsigned long)vm->addr, vm->caller);
+ nr_pages, addr, caller);
return true;
}
#endif
--
2.42.0.283.g2d96d420d3-goog
