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

kbuild test robot
2018-12-14T17:14:52Z

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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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