Commit 0818e739 authored by Joel Fernandes (Google)'s avatar Joel Fernandes (Google) Committed by Andrew Morton
Browse files

mm/vmalloc: add a safer version of find_vm_area() for debug 

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.]
Link: https://lkml.kernel.org/r/20230904180806.1002832-1-joel@joelfernandes.org


Fixes: 98f18083 ("mm: Make mem_dump_obj() handle vmalloc() memory")
Signed-off-by: default avatarJoel Fernandes (Google) <joel@joelfernandes.org>
Reviewed-by: default avatarUladzislau Rezki (Sony) <urezki@gmail.com>
Reported-by: default avatarZhen Lei <thunder.leizhen@huaweicloud.com>
Cc: Paul E. McKenney <paulmck@kernel.org>
Cc: Zqiang <qiang.zhang1211@gmail.com>
Cc: <stable@vger.kernel.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 7f33105c

mm/vmalloc.c

+22 −4
Original line number Diff line number Diff line
@@ -4278,14 +4278,32 @@ 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