linux-kernel - io_uring/kbuf.c:271:5-24: WARNING: atomic_dec_and_test variation before object free at line 273.

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Message-ID: <202410300609.JP8Dq6wz-lkp@intel.com>
Date: Wed, 30 Oct 2024 06:43:16 +0800
From: kernel test robot <lkp@...el.com>
To: Jens Axboe <axboe@...nel.dk>
Cc: oe-kbuild-all@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: io_uring/kbuf.c:271:5-24: WARNING: atomic_dec_and_test variation
 before object free at line 273.

Hi Jens,

FYI, the error/warning was bisected to this commit, please ignore it if it's irrelevant.

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   e42b1a9a2557aa94fee47f078633677198386a52
commit: 6b69c4ab4f685327d9e10caf0d84217ba23a8c4b io_uring/kbuf: protect io_buffer_list teardown with a reference
date:   7 months ago
config: arm-randconfig-r061-20241029 (https://download.01.org/0day-ci/archive/20241030/202410300609.JP8Dq6wz-lkp@intel.com/config)
compiler: arm-linux-gnueabi-gcc (GCC) 14.1.0

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@...el.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202410300609.JP8Dq6wz-lkp@intel.com/

cocci warnings: (new ones prefixed by >>)
>> io_uring/kbuf.c:271:5-24: WARNING: atomic_dec_and_test variation before object free at line 273.

vim +271 io_uring/kbuf.c

   268	
   269	static void io_put_bl(struct io_ring_ctx *ctx, struct io_buffer_list *bl)
   270	{
 > 271		if (atomic_dec_and_test(&bl->refs)) {
   272			__io_remove_buffers(ctx, bl, -1U);
 > 273			kfree_rcu(bl, rcu);
   274		}
   275	}
   276	

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki