| Message ID | bee11bfd9157e60aaea6db033a4af7c13c982c82.1717495894.git.baolin.wang@linux.alibaba.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | add mTHP support for anonymous shmem | expand |
Hi Baolin, kernel test robot noticed the following build warnings: [auto build test WARNING on akpm-mm/mm-everything] [also build test WARNING on linus/master v6.10-rc2 next-20240604] [If your patch is applied to the wrong git tree, kindly drop us a note. And when submitting patch, we suggest to use '--base' as documented in https://git-scm.com/docs/git-format-patch#_base_tree_information] url: https://github.com/intel-lab-lkp/linux/commits/Baolin-Wang/mm-memory-extend-finish_fault-to-support-large-folio/20240604-182028 base: https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-everything patch link: https://lore.kernel.org/r/bee11bfd9157e60aaea6db033a4af7c13c982c82.1717495894.git.baolin.wang%40linux.alibaba.com patch subject: [PATCH v4 1/6] mm: memory: extend finish_fault() to support large folio config: openrisc-allnoconfig (https://download.01.org/0day-ci/archive/20240604/202406042210.20LfqwNd-lkp@intel.com/config) compiler: or1k-linux-gcc (GCC) 13.2.0 reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240604/202406042210.20LfqwNd-lkp@intel.com/reproduce) 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@intel.com> | Closes: https://lore.kernel.org/oe-kbuild-all/202406042210.20LfqwNd-lkp@intel.com/ All warnings (new ones prefixed by >>): mm/memory.c: In function 'finish_fault': >> mm/memory.c:4838:29: warning: unused variable 'i' [-Wunused-variable] 4838 | int type, nr_pages, i; | ^ vim +/i +4838 mm/memory.c 4814 4815 /** 4816 * finish_fault - finish page fault once we have prepared the page to fault 4817 * 4818 * @vmf: structure describing the fault 4819 * 4820 * This function handles all that is needed to finish a page fault once the 4821 * page to fault in is prepared. It handles locking of PTEs, inserts PTE for 4822 * given page, adds reverse page mapping, handles memcg charges and LRU 4823 * addition. 4824 * 4825 * The function expects the page to be locked and on success it consumes a 4826 * reference of a page being mapped (for the PTE which maps it). 4827 * 4828 * Return: %0 on success, %VM_FAULT_ code in case of error. 4829 */ 4830 vm_fault_t finish_fault(struct vm_fault *vmf) 4831 { 4832 struct vm_area_struct *vma = vmf->vma; 4833 struct page *page; 4834 struct folio *folio; 4835 vm_fault_t ret; 4836 bool is_cow = (vmf->flags & FAULT_FLAG_WRITE) && 4837 !(vma->vm_flags & VM_SHARED); > 4838 int type, nr_pages, i; 4839 unsigned long addr = vmf->address; 4840 4841 /* Did we COW the page? */ 4842 if (is_cow) 4843 page = vmf->cow_page; 4844 else 4845 page = vmf->page; 4846 4847 /* 4848 * check even for read faults because we might have lost our CoWed 4849 * page 4850 */ 4851 if (!(vma->vm_flags & VM_SHARED)) { 4852 ret = check_stable_address_space(vma->vm_mm); 4853 if (ret) 4854 return ret; 4855 } 4856 4857 if (pmd_none(*vmf->pmd)) { 4858 if (PageTransCompound(page)) { 4859 ret = do_set_pmd(vmf, page); 4860 if (ret != VM_FAULT_FALLBACK) 4861 return ret; 4862 } 4863 4864 if (vmf->prealloc_pte) 4865 pmd_install(vma->vm_mm, vmf->pmd, &vmf->prealloc_pte); 4866 else if (unlikely(pte_alloc(vma->vm_mm, vmf->pmd))) 4867 return VM_FAULT_OOM; 4868 } 4869 4870 folio = page_folio(page); 4871 nr_pages = folio_nr_pages(folio); 4872 4873 /* 4874 * Using per-page fault to maintain the uffd semantics, and same 4875 * approach also applies to non-anonymous-shmem faults to avoid 4876 * inflating the RSS of the process. 4877 */ 4878 if (!vma_is_anon_shmem(vma) || unlikely(userfaultfd_armed(vma))) { 4879 nr_pages = 1; 4880 } else if (nr_pages > 1) { 4881 pgoff_t idx = folio_page_idx(folio, page); 4882 /* The page offset of vmf->address within the VMA. */ 4883 pgoff_t vma_off = vmf->pgoff - vmf->vma->vm_pgoff; 4884 4885 /* 4886 * Fallback to per-page fault in case the folio size in page 4887 * cache beyond the VMA limits. 4888 */ 4889 if (unlikely(vma_off < idx || 4890 vma_off + (nr_pages - idx) > vma_pages(vma))) { 4891 nr_pages = 1; 4892 } else { 4893 /* Now we can set mappings for the whole large folio. */ 4894 addr = vmf->address - idx * PAGE_SIZE; 4895 page = &folio->page; 4896 } 4897 } 4898 4899 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, 4900 addr, &vmf->ptl); 4901 if (!vmf->pte) 4902 return VM_FAULT_NOPAGE; 4903 4904 /* Re-check under ptl */ 4905 if (nr_pages == 1 && unlikely(vmf_pte_changed(vmf))) { 4906 update_mmu_tlb(vma, addr, vmf->pte); 4907 ret = VM_FAULT_NOPAGE; 4908 goto unlock; 4909 } else if (nr_pages > 1 && !pte_range_none(vmf->pte, nr_pages)) { 4910 update_mmu_tlb_range(vma, addr, vmf->pte, nr_pages); 4911 ret = VM_FAULT_NOPAGE; 4912 goto unlock; 4913 } 4914 4915 folio_ref_add(folio, nr_pages - 1); 4916 set_pte_range(vmf, folio, page, nr_pages, addr); 4917 type = is_cow ? MM_ANONPAGES : mm_counter_file(folio); 4918 add_mm_counter(vma->vm_mm, type, nr_pages); 4919 ret = 0; 4920 4921 unlock: 4922 pte_unmap_unlock(vmf->pte, vmf->ptl); 4923 return ret; 4924 } 4925
On 2024/6/4 22:58, kernel test robot wrote: > Hi Baolin, > > kernel test robot noticed the following build warnings: > > [auto build test WARNING on akpm-mm/mm-everything] > [also build test WARNING on linus/master v6.10-rc2 next-20240604] > [If your patch is applied to the wrong git tree, kindly drop us a note. > And when submitting patch, we suggest to use '--base' as documented in > https://git-scm.com/docs/git-format-patch#_base_tree_information] > > url: https://github.com/intel-lab-lkp/linux/commits/Baolin-Wang/mm-memory-extend-finish_fault-to-support-large-folio/20240604-182028 > base: https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-everything > patch link: https://lore.kernel.org/r/bee11bfd9157e60aaea6db033a4af7c13c982c82.1717495894.git.baolin.wang%40linux.alibaba.com > patch subject: [PATCH v4 1/6] mm: memory: extend finish_fault() to support large folio > config: openrisc-allnoconfig (https://download.01.org/0day-ci/archive/20240604/202406042210.20LfqwNd-lkp@intel.com/config) > compiler: or1k-linux-gcc (GCC) 13.2.0 > reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240604/202406042210.20LfqwNd-lkp@intel.com/reproduce) > > 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@intel.com> > | Closes: https://lore.kernel.org/oe-kbuild-all/202406042210.20LfqwNd-lkp@intel.com/ > > All warnings (new ones prefixed by >>): > > mm/memory.c: In function 'finish_fault': >>> mm/memory.c:4838:29: warning: unused variable 'i' [-Wunused-variable] > 4838 | int type, nr_pages, i; > | ^ Oops, thanks for reporting. Forgot to remove the variable 'i' when changing to use update_mmu_tlb_range(). I see Andrew has already helped to remove this unused variable 'i'. Thanks Andrew.
diff --git a/mm/memory.c b/mm/memory.c index eef4e482c0c2..1f7be4c6aac4 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -4831,9 +4831,12 @@ vm_fault_t finish_fault(struct vm_fault *vmf) { struct vm_area_struct *vma = vmf->vma; struct page *page; + struct folio *folio; vm_fault_t ret; bool is_cow = (vmf->flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED); + int type, nr_pages, i; + unsigned long addr = vmf->address; /* Did we COW the page? */ if (is_cow) @@ -4864,24 +4867,58 @@ vm_fault_t finish_fault(struct vm_fault *vmf) return VM_FAULT_OOM; } + folio = page_folio(page); + nr_pages = folio_nr_pages(folio); + + /* + * Using per-page fault to maintain the uffd semantics, and same + * approach also applies to non-anonymous-shmem faults to avoid + * inflating the RSS of the process. + */ + if (!vma_is_anon_shmem(vma) || unlikely(userfaultfd_armed(vma))) { + nr_pages = 1; + } else if (nr_pages > 1) { + pgoff_t idx = folio_page_idx(folio, page); + /* The page offset of vmf->address within the VMA. */ + pgoff_t vma_off = vmf->pgoff - vmf->vma->vm_pgoff; + + /* + * Fallback to per-page fault in case the folio size in page + * cache beyond the VMA limits. + */ + if (unlikely(vma_off < idx || + vma_off + (nr_pages - idx) > vma_pages(vma))) { + nr_pages = 1; + } else { + /* Now we can set mappings for the whole large folio. */ + addr = vmf->address - idx * PAGE_SIZE; + page = &folio->page; + } + } + vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, - vmf->address, &vmf->ptl); + addr, &vmf->ptl); if (!vmf->pte) return VM_FAULT_NOPAGE; /* Re-check under ptl */ - if (likely(!vmf_pte_changed(vmf))) { - struct folio *folio = page_folio(page); - int type = is_cow ? MM_ANONPAGES : mm_counter_file(folio); - - set_pte_range(vmf, folio, page, 1, vmf->address); - add_mm_counter(vma->vm_mm, type, 1); - ret = 0; - } else { - update_mmu_tlb(vma, vmf->address, vmf->pte); + if (nr_pages == 1 && unlikely(vmf_pte_changed(vmf))) { + update_mmu_tlb(vma, addr, vmf->pte); + ret = VM_FAULT_NOPAGE; + goto unlock; + } else if (nr_pages > 1 && !pte_range_none(vmf->pte, nr_pages)) { + update_mmu_tlb_range(vma, addr, vmf->pte, nr_pages); ret = VM_FAULT_NOPAGE; + goto unlock; } + folio_ref_add(folio, nr_pages - 1); + set_pte_range(vmf, folio, page, nr_pages, addr); + type = is_cow ? MM_ANONPAGES : mm_counter_file(folio); + add_mm_counter(vma->vm_mm, type, nr_pages); + ret = 0; + +unlock: pte_unmap_unlock(vmf->pte, vmf->ptl); return ret; }
Add large folio mapping establishment support for finish_fault() as a preparation, to support multi-size THP allocation of anonymous shmem pages in the following patches. Keep the same behavior (per-page fault) for non-anon shmem to avoid inflating the RSS unintentionally, and we can discuss what size of mapping to build when extending mTHP to control non-anon shmem in the future. Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com> --- mm/memory.c | 57 +++++++++++++++++++++++++++++++++++++++++++---------- 1 file changed, 47 insertions(+), 10 deletions(-)