CC: [email protected]
CC: [email protected]
TO: Dmitry Osipenko <[email protected]>
CC: Joerg Roedel <[email protected]>

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 
master
head:   23859ae44402f4d935b9ee548135dd1e65e2cbf4
commit: 404d0b308e4f730b1c9b2f33e84a6f7069db94c5 iommu/tegra-smmu: Add locking 
around mapping operations
date:   8 weeks ago
:::::: branch date: 6 hours ago
:::::: commit date: 8 weeks ago
config: arm64-randconfig-s032-20201029 (attached as .config)
compiler: aarch64-linux-gcc (GCC) 9.3.0
reproduce:
        wget 
https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O 
~/bin/make.cross
        chmod +x ~/bin/make.cross
        # apt-get install sparse
        # sparse version: v0.6.3-56-gc09e8239-dirty
        # 
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=404d0b308e4f730b1c9b2f33e84a6f7069db94c5
        git remote add linus 
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
        git fetch --no-tags linus master
        git checkout 404d0b308e4f730b1c9b2f33e84a6f7069db94c5
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross C=1 
CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__' ARCH=arm64 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <[email protected]>


"sparse warnings: (new ones prefixed by >>)"
>> drivers/iommu/tegra-smmu.c:687:9: sparse: sparse: context imbalance in 
>> 'as_get_pde_page' - different lock contexts for basic block

vim +/as_get_pde_page +687 drivers/iommu/tegra-smmu.c

8482ee5ea109744 Russell King    2015-07-27  657  
404d0b308e4f730 Dmitry Osipenko 2020-09-01  658  static struct page 
*as_get_pde_page(struct tegra_smmu_as *as,
404d0b308e4f730 Dmitry Osipenko 2020-09-01  659                                 
    unsigned long iova, gfp_t gfp,
404d0b308e4f730 Dmitry Osipenko 2020-09-01  660                                 
    unsigned long *flags)
404d0b308e4f730 Dmitry Osipenko 2020-09-01  661  {
404d0b308e4f730 Dmitry Osipenko 2020-09-01  662         unsigned int pde = 
iova_pd_index(iova);
404d0b308e4f730 Dmitry Osipenko 2020-09-01  663         struct page *page = 
as->pts[pde];
404d0b308e4f730 Dmitry Osipenko 2020-09-01  664  
404d0b308e4f730 Dmitry Osipenko 2020-09-01  665         /* at first check 
whether allocation needs to be done at all */
404d0b308e4f730 Dmitry Osipenko 2020-09-01  666         if (page)
404d0b308e4f730 Dmitry Osipenko 2020-09-01  667                 return page;
404d0b308e4f730 Dmitry Osipenko 2020-09-01  668  
404d0b308e4f730 Dmitry Osipenko 2020-09-01  669         /*
404d0b308e4f730 Dmitry Osipenko 2020-09-01  670          * In order to prevent 
exhaustion of the atomic memory pool, we
404d0b308e4f730 Dmitry Osipenko 2020-09-01  671          * allocate page in a 
sleeping context if GFP flags permit. Hence
404d0b308e4f730 Dmitry Osipenko 2020-09-01  672          * spinlock needs to be 
unlocked and re-locked after allocation.
404d0b308e4f730 Dmitry Osipenko 2020-09-01  673          */
404d0b308e4f730 Dmitry Osipenko 2020-09-01  674         if (!(gfp & 
__GFP_ATOMIC))
404d0b308e4f730 Dmitry Osipenko 2020-09-01  675                 
spin_unlock_irqrestore(&as->lock, *flags);
404d0b308e4f730 Dmitry Osipenko 2020-09-01  676  
404d0b308e4f730 Dmitry Osipenko 2020-09-01  677         page = alloc_page(gfp | 
__GFP_DMA | __GFP_ZERO);
404d0b308e4f730 Dmitry Osipenko 2020-09-01  678  
404d0b308e4f730 Dmitry Osipenko 2020-09-01  679         if (!(gfp & 
__GFP_ATOMIC))
404d0b308e4f730 Dmitry Osipenko 2020-09-01  680                 
spin_lock_irqsave(&as->lock, *flags);
404d0b308e4f730 Dmitry Osipenko 2020-09-01  681  
404d0b308e4f730 Dmitry Osipenko 2020-09-01  682         /*
404d0b308e4f730 Dmitry Osipenko 2020-09-01  683          * In a case of 
blocking allocation, a concurrent mapping may win
404d0b308e4f730 Dmitry Osipenko 2020-09-01  684          * the PDE allocation. 
In this case the allocated page isn't needed
404d0b308e4f730 Dmitry Osipenko 2020-09-01  685          * if allocation 
succeeded and the allocation failure isn't fatal.
404d0b308e4f730 Dmitry Osipenko 2020-09-01  686          */
404d0b308e4f730 Dmitry Osipenko 2020-09-01 @687         if (as->pts[pde]) {
404d0b308e4f730 Dmitry Osipenko 2020-09-01  688                 if (page)
404d0b308e4f730 Dmitry Osipenko 2020-09-01  689                         
__free_page(page);
404d0b308e4f730 Dmitry Osipenko 2020-09-01  690  
404d0b308e4f730 Dmitry Osipenko 2020-09-01  691                 page = 
as->pts[pde];
404d0b308e4f730 Dmitry Osipenko 2020-09-01  692         }
404d0b308e4f730 Dmitry Osipenko 2020-09-01  693  
404d0b308e4f730 Dmitry Osipenko 2020-09-01  694         return page;
404d0b308e4f730 Dmitry Osipenko 2020-09-01  695  }
404d0b308e4f730 Dmitry Osipenko 2020-09-01  696  

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/[email protected]

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