Re: [PATCH] mm, memcg: fix reclaim deadlock with writeback

[kbuild test robot]

Hi Michal,

I love your patch! Yet something to improve:

[auto build test ERROR on linus/master]
[also build test ERROR on v4.20-rc6 next-20181214]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/Michal-Hocko/mm-memcg-fix-reclaim-deadlock-with-writeback/20181212-224633
config: nds32-allmodconfig (attached as .config)
compiler: nds32le-linux-gcc (GCC) 6.4.0
reproduce:
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # save the attached .config to linux build tree
        GCC_VERSION=6.4.0 make.cross ARCH=nds32 

All errors (new ones prefixed by >>):

   mm/memory.c: In function '__do_fault':
   mm/memory.c:3001:45: error: 'struct vm_area_struct' has no member named 'vm'
      vmf->prealloc_pte = pte_alloc_one(vmf->vma->vm>mm, vmf->address);
                                                ^~
>> mm/memory.c:3001:50: error: 'mm' undeclared (first use in this function)
      vmf->prealloc_pte = pte_alloc_one(vmf->vma->vm>mm, vmf->address);
                                                     ^~
   mm/memory.c:3001:50: note: each undeclared identifier is reported only once for each function it appears in

vim +/mm +3001 mm/memory.c

  2985	
  2986	/*
  2987	 * The mmap_sem must have been held on entry, and may have been
  2988	 * released depending on flags and vma->vm_ops->fault() return value.
  2989	 * See filemap_fault() and __lock_page_retry().
  2990	 */
  2991	static vm_fault_t __do_fault(struct vm_fault *vmf)
  2992	{
  2993		struct vm_area_struct *vma = vmf->vma;
  2994		vm_fault_t ret;
  2995	
  2996		/*
  2997		 * Preallocate pte before we take page_lock because this might lead to
  2998		 * deadlocks for memcg reclaim which waits for pages under writeback.
  2999		 */
  3000		if (pmd_none(*vmf->pmd) && !vmf->prealloc_pte) {
> 3001			vmf->prealloc_pte = pte_alloc_one(vmf->vma->vm>mm, vmf->address);
  3002			if (!vmf->prealloc_pte)
  3003				return VM_FAULT_OOM;
  3004			smp_wmb(); /* See comment in __pte_alloc() */
  3005		}
  3006	
  3007		ret = vma->vm_ops->fault(vmf);
  3008		if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY |
  3009				    VM_FAULT_DONE_COW)))
  3010			return ret;
  3011	
  3012		if (unlikely(PageHWPoison(vmf->page))) {
  3013			if (ret & VM_FAULT_LOCKED)
  3014				unlock_page(vmf->page);
  3015			put_page(vmf->page);
  3016			vmf->page = NULL;
  3017			return VM_FAULT_HWPOISON;
  3018		}
  3019	
  3020		if (unlikely(!(ret & VM_FAULT_LOCKED)))
  3021			lock_page(vmf->page);
  3022		else
  3023			VM_BUG_ON_PAGE(!PageLocked(vmf->page), vmf->page);
  3024	
  3025		return ret;
  3026	}
  3027	

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