[linux-next:master 465/14131] include/asm-generic/bitops/instrumented-lock.h:40:25: sparse: sparse: context imbalance in 'dm_exception_table_unlock' - unexpected unlock

[linux-next:master 465/14131] include/asm-generic/bitops/instrumented-lock.h:40:25: sparse: sparse: context imbalance in 'dm_exception_table_unlock' - unexpected unlock

[kbuild test robot]

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CC: kbuild-all(a)lists.01.org
TO: "Marco, Elver," <elver@google.com>
CC: Ingo Molnar <mingo@kernel.org>
CC: "Paul E. McKenney" <paulmck@kernel.org>

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master
head:   e7b08814b16b80a0bf76eeca16317f8c2ed23b8c
commit: 27f937cc810aef63b0752f5bfbf383390dd076a1 [465/14131] asm-generic, kcsan: Add KCSAN instrumentation for bitops
:::::: branch date: 3 days ago
:::::: commit date: 2 months ago
config: x86_64-randconfig-s022-20200601 (attached as .config)
compiler: gcc-9 (Debian 9.3.0-13) 9.3.0
reproduce:
        # apt-get install sparse
        # sparse version: v0.6.1-243-gc100a7ab-dirty
        git checkout 27f937cc810aef63b0752f5bfbf383390dd076a1
        # save the attached .config to linux build tree
        make W=1 C=1 ARCH=x86_64 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__'

If you fix the issue, kindly add following tag as appropriate
Reported-by: kbuild test robot <lkp@intel.com>


sparse warnings: (new ones prefixed by >>)

   drivers/md/dm-snap.c:642:13: sparse: sparse: context imbalance in 'dm_exception_table_lock' - wrong count at exit
>> include/asm-generic/bitops/instrumented-lock.h:40:25: sparse: sparse: context imbalance in 'dm_exception_table_unlock' - unexpected unlock

# https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/?id=27f937cc810aef63b0752f5bfbf383390dd076a1
git remote add linux-next https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git
git remote update linux-next
git checkout 27f937cc810aef63b0752f5bfbf383390dd076a1
vim +/dm_exception_table_unlock +40 include/asm-generic/bitops/instrumented-lock.h

81d2c6f81996e0 Daniel Axtens 2019-08-20  28  
81d2c6f81996e0 Daniel Axtens 2019-08-20  29  /**
81d2c6f81996e0 Daniel Axtens 2019-08-20  30   * __clear_bit_unlock - Clears a bit in memory
81d2c6f81996e0 Daniel Axtens 2019-08-20  31   * @nr: Bit to clear
81d2c6f81996e0 Daniel Axtens 2019-08-20  32   * @addr: Address to start counting from
81d2c6f81996e0 Daniel Axtens 2019-08-20  33   *
81d2c6f81996e0 Daniel Axtens 2019-08-20  34   * This is a non-atomic operation but implies a release barrier before the
81d2c6f81996e0 Daniel Axtens 2019-08-20  35   * memory operation. It can be used for an unlock if no other CPUs can
81d2c6f81996e0 Daniel Axtens 2019-08-20  36   * concurrently modify other bits in the word.
81d2c6f81996e0 Daniel Axtens 2019-08-20  37   */
81d2c6f81996e0 Daniel Axtens 2019-08-20  38  static inline void __clear_bit_unlock(long nr, volatile unsigned long *addr)
81d2c6f81996e0 Daniel Axtens 2019-08-20  39  {
27f937cc810aef Marco Elver   2020-01-21 @40  	instrument_write(addr + BIT_WORD(nr), sizeof(long));
81d2c6f81996e0 Daniel Axtens 2019-08-20  41  	arch___clear_bit_unlock(nr, addr);
81d2c6f81996e0 Daniel Axtens 2019-08-20  42  }
81d2c6f81996e0 Daniel Axtens 2019-08-20  43  

---
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