Re: [linux-next:master 12999/13245] mm/vmalloc.c:4652:25: warning: variable 'addr' is uninitialized when used here

[Uladzislau Rezki <urezki@gmail.com>]

On Thu, Jan 11, 2024 at 01:13:59PM +0800, kernel test robot wrote:
> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master
> head:   9e21984d62c56a0f6d1fc6f76b646212cfd7fe88
> commit: e88b85b81d5313a69cb62829b957d4a9ecde600b [12999/13245] mm: vmalloc: offload free_vmap_area_lock lock
> config: arm-defconfig (https://download.01.org/0day-ci/archive/20240111/202401111304.N5dkFGNe-lkp@intel.com/config)
> compiler: clang version 14.0.6 (https://github.com/llvm/llvm-project.git f28c006a5895fc0e329fe15fead81e37457cb1d1)
> reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240111/202401111304.N5dkFGNe-lkp@intel.com/reproduce)
> 
> If you fix the issue in a separate patch/commit (i.e. not just a new version of
> the same patch/commit), kindly add following tags
> | Reported-by: kernel test robot <lkp@intel.com>
> | Closes: https://lore.kernel.org/oe-kbuild-all/202401111304.N5dkFGNe-lkp@intel.com/
> 
> All warnings (new ones prefixed by >>):
> 
> >> mm/vmalloc.c:4652:25: warning: variable 'addr' is uninitialized when used here [-Wuninitialized]
>                    va = __find_vmap_area(addr, &vn->busy.root);
>                                          ^~~~
>    mm/vmalloc.c:4645:20: note: initialize the variable 'addr' to silence this warning
>            unsigned long addr;
>                              ^
>                               = 0
>    1 warning generated.
> 
> 
> vim +/addr +4652 mm/vmalloc.c
> 
> a10aa579878fc6 Christoph Lameter       2008-04-28  4637  
> 5bb1bb353cfe34 Paul E. McKenney        2021-01-07  4638  #ifdef CONFIG_PRINTK
> 98f180837a896e Paul E. McKenney        2020-12-08  4639  bool vmalloc_dump_obj(void *object)
> 98f180837a896e Paul E. McKenney        2020-12-08  4640  {
> 98f180837a896e Paul E. McKenney        2020-12-08  4641  	void *objp = (void *)PAGE_ALIGN((unsigned long)object);
> 0818e739b5c061 Joel Fernandes (Google  2023-09-04  4642) 	const void *caller;
> 0818e739b5c061 Joel Fernandes (Google  2023-09-04  4643) 	struct vmap_area *va;
> 86817057732a9c Uladzislau Rezki (Sony  2024-01-02  4644) 	struct vmap_node *vn;
> 0818e739b5c061 Joel Fernandes (Google  2023-09-04  4645) 	unsigned long addr;
> 0818e739b5c061 Joel Fernandes (Google  2023-09-04  4646) 	unsigned int nr_pages;
> 86817057732a9c Uladzislau Rezki (Sony  2024-01-02  4647) 	bool success = false;
> 98f180837a896e Paul E. McKenney        2020-12-08  4648  
> 86817057732a9c Uladzislau Rezki (Sony  2024-01-02  4649) 	vn = addr_to_node((unsigned long)objp);
> 86817057732a9c Uladzislau Rezki (Sony  2024-01-02  4650) 
> 86817057732a9c Uladzislau Rezki (Sony  2024-01-02  4651) 	if (spin_trylock(&vn->busy.lock)) {
> 86817057732a9c Uladzislau Rezki (Sony  2024-01-02 @4652) 		va = __find_vmap_area(addr, &vn->busy.root);
> 86817057732a9c Uladzislau Rezki (Sony  2024-01-02  4653) 
> 86817057732a9c Uladzislau Rezki (Sony  2024-01-02  4654) 		if (va && va->vm) {
> 86817057732a9c Uladzislau Rezki (Sony  2024-01-02  4655) 			addr = (unsigned long)va->vm->addr;
> 86817057732a9c Uladzislau Rezki (Sony  2024-01-02  4656) 			caller = va->vm->caller;
> 86817057732a9c Uladzislau Rezki (Sony  2024-01-02  4657) 			nr_pages = va->vm->nr_pages;
> 86817057732a9c Uladzislau Rezki (Sony  2024-01-02  4658) 			success = true;
> 0818e739b5c061 Joel Fernandes (Google  2023-09-04  4659) 		}
> 0818e739b5c061 Joel Fernandes (Google  2023-09-04  4660) 
> 86817057732a9c Uladzislau Rezki (Sony  2024-01-02  4661) 		spin_unlock(&vn->busy.lock);
> 0818e739b5c061 Joel Fernandes (Google  2023-09-04  4662) 	}
> 86817057732a9c Uladzislau Rezki (Sony  2024-01-02  4663) 
> 86817057732a9c Uladzislau Rezki (Sony  2024-01-02  4664) 	if (success)
> bd34dcd4120d7e Paul E. McKenney        2020-12-09  4665  		pr_cont(" %u-page vmalloc region starting at %#lx allocated at %pS\n",
> 0818e739b5c061 Joel Fernandes (Google  2023-09-04  4666) 			nr_pages, addr, caller);
> 86817057732a9c Uladzislau Rezki (Sony  2024-01-02  4667) 
> 86817057732a9c Uladzislau Rezki (Sony  2024-01-02  4668) 	return success;
> 98f180837a896e Paul E. McKenney        2020-12-08  4669  }
> 5bb1bb353cfe34 Paul E. McKenney        2021-01-07  4670  #endif
> 98f180837a896e Paul E. McKenney        2020-12-08  4671  
> 
> :::::: The code at line 4652 was first introduced by commit
> :::::: 86817057732a9ce9cefdb6f513b6554a55ebbbbb mm: vmalloc: remove global vmap_area_root rb-tree
> 
> :::::: TO: Uladzislau Rezki (Sony) <urezki@gmail.com>
> :::::: CC: Andrew Morton <akpm@linux-foundation.org>
> 
> -- 
> 0-DAY CI Kernel Test Service
> https://github.com/intel/lkp-tests/wiki

Same, i sent the patch, but just in case i post it here:

<snip>
From fa613edf6c3d700a02ef109cbd42633b5df30abb Mon Sep 17 00:00:00 2001
From: "Uladzislau Rezki (Sony)" <urezki@gmail.com>
Date: Thu, 11 Jan 2024 13:04:07 +0100
Subject: [PATCH 1/2] mm: vmalloc: Fix a wrong value passed to
 __find_vmap_area()

There was a type in the vmalloc_dump_obj() function. Instead
of passing a real address which is "objp" an "addr" was used
what is wrong and not initialized.

Reported-by: kernel test robot <lkp@intel.com>
Fixes: e88b85b81d5 ("mm: vmalloc: offload free_vmap_area_lock lock")
Closes: https://lore.kernel.org/oe-kbuild-all/202401111810.TKPIXLCs-lkp@intel.com/
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
---
 mm/vmalloc.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index e30dabf68263..43a6608e1397 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -4688,7 +4688,7 @@ bool vmalloc_dump_obj(void *object)
 	vn = addr_to_node((unsigned long)objp);
 
 	if (spin_trylock(&vn->busy.lock)) {
-		va = __find_vmap_area(addr, &vn->busy.root);
+		va = __find_vmap_area((unsigned long)objp, &vn->busy.root);
 
 		if (va && va->vm) {
 			addr = (unsigned long)va->vm->addr;
-- 
2.39.2
<snip>

it can be folded into: e88b85b81d5 ("mm: vmalloc: offload free_vmap_area_lock lock")
or applied as a separate patch.

--
Uladzislau Rezki