diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c index 5b0f93f73837..111fe73bb8a7 100644 --- a/fs/xfs/xfs_file.c +++ b/fs/xfs/xfs_file.c @@ -1319,17 +1319,19 @@ xfs_filemap_pfn_mkwrite( return __xfs_filemap_fault(vmf, PE_SIZE_PTE, true); } -static void +static vm_fault_t xfs_filemap_map_pages( struct vm_fault *vmf, pgoff_t start_pgoff, pgoff_t end_pgoff) { struct inode *inode = file_inode(vmf->vma->vm_file); + vm_fault_t ret; xfs_ilock(XFS_I(inode), XFS_MMAPLOCK_SHARED); - filemap_map_pages(vmf, start_pgoff, end_pgoff); + ret = filemap_map_pages(vmf, start_pgoff, end_pgoff); xfs_iunlock(XFS_I(inode), XFS_MMAPLOCK_SHARED); + return ret; } static const struct vm_operations_struct xfs_file_vm_ops = { diff --git a/include/linux/mm.h b/include/linux/mm.h index ecdf8a8cd6ae..4572a9bc5862 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -542,8 +542,8 @@ struct vm_fault { * is not NULL, otherwise pmd. */ pgtable_t prealloc_pte; /* Pre-allocated pte page table. - * vm_ops->map_pages() calls - * alloc_set_pte() from atomic context. + * vm_ops->map_pages() sets up a page + * table from atomic context. * do_fault_around() pre-allocates * page table to avoid allocation from * atomic context. @@ -578,7 +578,7 @@ struct vm_operations_struct { vm_fault_t (*fault)(struct vm_fault *vmf); vm_fault_t (*huge_fault)(struct vm_fault *vmf, enum page_entry_size pe_size); - void (*map_pages)(struct vm_fault *vmf, + vm_fault_t (*map_pages)(struct vm_fault *vmf, pgoff_t start_pgoff, pgoff_t end_pgoff); unsigned long (*pagesize)(struct vm_area_struct * area); @@ -988,7 +988,9 @@ static inline pte_t maybe_mkwrite(pte_t pte, struct vm_area_struct *vma) return pte; } -vm_fault_t alloc_set_pte(struct vm_fault *vmf, struct page *page); +vm_fault_t do_set_pmd(struct vm_fault *vmf, struct page *page); +void do_set_pte(struct vm_fault *vmf, struct page *page); + vm_fault_t finish_fault(struct vm_fault *vmf); vm_fault_t finish_mkwrite_fault(struct vm_fault *vmf); #endif @@ -2622,7 +2624,7 @@ extern void truncate_inode_pages_final(struct address_space *); /* generic vm_area_ops exported for stackable file systems */ extern vm_fault_t filemap_fault(struct vm_fault *vmf); -extern void filemap_map_pages(struct vm_fault *vmf, +extern vm_fault_t filemap_map_pages(struct vm_fault *vmf, pgoff_t start_pgoff, pgoff_t end_pgoff); extern vm_fault_t filemap_page_mkwrite(struct vm_fault *vmf); diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h index 8fcdfa52eb4b..36eb748f3c97 100644 --- a/include/linux/pgtable.h +++ b/include/linux/pgtable.h @@ -1314,6 +1314,17 @@ static inline int pmd_trans_unstable(pmd_t *pmd) #endif } +/* + * the ordering of these checks is important for pmds with _page_devmap set. + * if we check pmd_trans_unstable() first we will trip the bad_pmd() check + * inside of pmd_none_or_trans_huge_or_clear_bad(). this will end up correctly + * returning 1 but not before it spams dmesg with the pmd_clear_bad() output. + */ +static inline int pmd_devmap_trans_unstable(pmd_t *pmd) +{ + return pmd_devmap(*pmd) || pmd_trans_unstable(pmd); +} + #ifndef CONFIG_NUMA_BALANCING /* * Technically a PTE can be PROTNONE even when not doing NUMA balancing but diff --git a/mm/filemap.c b/mm/filemap.c index 5c9d564317a5..c1f2dc89b8a7 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -42,6 +42,7 @@ #include #include #include +#include #include "internal.h" #define CREATE_TRACE_POINTS @@ -2911,74 +2912,164 @@ vm_fault_t filemap_fault(struct vm_fault *vmf) } EXPORT_SYMBOL(filemap_fault); -void filemap_map_pages(struct vm_fault *vmf, - pgoff_t start_pgoff, pgoff_t end_pgoff) +static bool filemap_map_pmd(struct vm_fault *vmf, struct page *page) { - struct file *file = vmf->vma->vm_file; + struct mm_struct *mm = vmf->vma->vm_mm; + + /* Huge page is mapped? No need to proceed. */ + if (pmd_trans_huge(*vmf->pmd)) { + unlock_page(page); + put_page(page); + return true; + } + + if (pmd_none(*vmf->pmd) && PageTransHuge(page)) { + vm_fault_t ret = do_set_pmd(vmf, page); + if (!ret) { + /* The page is mapped successfully, reference consumed. */ + unlock_page(page); + return true; + } + } + + if (pmd_none(*vmf->pmd)) { + vmf->ptl = pmd_lock(mm, vmf->pmd); + if (likely(pmd_none(*vmf->pmd))) { + mm_inc_nr_ptes(mm); + pmd_populate(mm, vmf->pmd, vmf->prealloc_pte); + vmf->prealloc_pte = NULL; + } + spin_unlock(vmf->ptl); + } + + /* See comment in handle_pte_fault() */ + if (pmd_devmap_trans_unstable(vmf->pmd)) { + unlock_page(page); + put_page(page); + return true; + } + + return false; +} + +static struct page *next_uptodate_page(struct page *page, + struct address_space *mapping, + struct xa_state *xas, pgoff_t end_pgoff) +{ + unsigned long max_idx; + + do { + if (!page) + return NULL; + if (xas_retry(xas, page)) + continue; + if (xa_is_value(page)) + continue; + if (PageLocked(page)) + continue; + if (!page_cache_get_speculative(page)) + continue; + /* Has the page moved or been split? */ + if (unlikely(page != xas_reload(xas))) + goto skip; + if (!PageUptodate(page) || PageReadahead(page)) + goto skip; + if (PageHWPoison(page)) + goto skip; + if (!trylock_page(page)) + goto skip; + if (page->mapping != mapping) + goto unlock; + if (!PageUptodate(page)) + goto unlock; + max_idx = DIV_ROUND_UP(i_size_read(mapping->host), PAGE_SIZE); + if (xas->xa_index >= max_idx) + goto unlock; + return page; +unlock: + unlock_page(page); +skip: + put_page(page); + } while ((page = xas_next_entry(xas, end_pgoff)) != NULL); + + return NULL; +} + +static inline struct page *first_map_page(struct address_space *mapping, + struct xa_state *xas, + pgoff_t end_pgoff) +{ + return next_uptodate_page(xas_find(xas, end_pgoff), + mapping, xas, end_pgoff); +} + +static inline struct page *next_map_page(struct address_space *mapping, + struct xa_state *xas, + pgoff_t end_pgoff) +{ + return next_uptodate_page(xas_next_entry(xas, end_pgoff), + mapping, xas, end_pgoff); +} + +vm_fault_t filemap_map_pages(struct vm_fault *vmf, + pgoff_t start_pgoff, pgoff_t end_pgoff) +{ + struct vm_area_struct *vma = vmf->vma; + struct file *file = vma->vm_file; struct address_space *mapping = file->f_mapping; pgoff_t last_pgoff = start_pgoff; - unsigned long max_idx; + unsigned long address = vmf->address; XA_STATE(xas, &mapping->i_pages, start_pgoff); struct page *head, *page; unsigned int mmap_miss = READ_ONCE(file->f_ra.mmap_miss); + vm_fault_t ret = 0; rcu_read_lock(); - xas_for_each(&xas, head, end_pgoff) { - if (xas_retry(&xas, head)) - continue; - if (xa_is_value(head)) - goto next; + head = first_map_page(mapping, &xas, end_pgoff); + if (!head) + goto out; - /* - * Check for a locked page first, as a speculative - * reference may adversely influence page migration. - */ - if (PageLocked(head)) - goto next; - if (!page_cache_get_speculative(head)) - goto next; + if (filemap_map_pmd(vmf, head)) { + ret = VM_FAULT_NOPAGE; + goto out; + } - /* Has the page moved or been split? */ - if (unlikely(head != xas_reload(&xas))) - goto skip; + vmf->address = vma->vm_start + ((start_pgoff - vma->vm_pgoff) << PAGE_SHIFT); + vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address, &vmf->ptl); + do { page = find_subpage(head, xas.xa_index); - - if (!PageUptodate(head) || - PageReadahead(page) || - PageHWPoison(page)) - goto skip; - if (!trylock_page(head)) - goto skip; - - if (head->mapping != mapping || !PageUptodate(head)) - goto unlock; - - max_idx = DIV_ROUND_UP(i_size_read(mapping->host), PAGE_SIZE); - if (xas.xa_index >= max_idx) + if (PageHWPoison(page)) goto unlock; if (mmap_miss > 0) mmap_miss--; vmf->address += (xas.xa_index - last_pgoff) << PAGE_SHIFT; - if (vmf->pte) - vmf->pte += xas.xa_index - last_pgoff; + vmf->pte += xas.xa_index - last_pgoff; last_pgoff = xas.xa_index; - if (alloc_set_pte(vmf, page)) + + if (!pte_none(*vmf->pte)) goto unlock; + + do_set_pte(vmf, page); + /* no need to invalidate: a not-present page won't be cached */ + update_mmu_cache(vma, vmf->address, vmf->pte); unlock_page(head); - goto next; + + /* The fault is handled */ + if (vmf->address == address) + ret = VM_FAULT_NOPAGE; + continue; unlock: unlock_page(head); -skip: put_page(head); -next: - /* Huge page is mapped? No need to proceed. */ - if (pmd_trans_huge(*vmf->pmd)) - break; - } + } while ((head = next_map_page(mapping, &xas, end_pgoff)) != NULL); + pte_unmap_unlock(vmf->pte, vmf->ptl); +out: rcu_read_unlock(); + vmf->address = address; WRITE_ONCE(file->f_ra.mmap_miss, mmap_miss); + return ret; } EXPORT_SYMBOL(filemap_map_pages); diff --git a/mm/memory.c b/mm/memory.c index feff48e1465a..3e2fc2950ad7 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -3503,7 +3503,7 @@ static vm_fault_t do_anonymous_page(struct vm_fault *vmf) if (pte_alloc(vma->vm_mm, vmf->pmd)) return VM_FAULT_OOM; - /* See the comment in pte_alloc_one_map() */ + /* See comment in handle_pte_fault() */ if (unlikely(pmd_trans_unstable(vmf->pmd))) return 0; @@ -3643,66 +3643,6 @@ static vm_fault_t __do_fault(struct vm_fault *vmf) return ret; } -/* - * The ordering of these checks is important for pmds with _PAGE_DEVMAP set. - * If we check pmd_trans_unstable() first we will trip the bad_pmd() check - * inside of pmd_none_or_trans_huge_or_clear_bad(). This will end up correctly - * returning 1 but not before it spams dmesg with the pmd_clear_bad() output. - */ -static int pmd_devmap_trans_unstable(pmd_t *pmd) -{ - return pmd_devmap(*pmd) || pmd_trans_unstable(pmd); -} - -static vm_fault_t pte_alloc_one_map(struct vm_fault *vmf) -{ - struct vm_area_struct *vma = vmf->vma; - - if (!pmd_none(*vmf->pmd)) - goto map_pte; - if (vmf->prealloc_pte) { - vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); - if (unlikely(!pmd_none(*vmf->pmd))) { - spin_unlock(vmf->ptl); - goto map_pte; - } - - mm_inc_nr_ptes(vma->vm_mm); - pmd_populate(vma->vm_mm, vmf->pmd, vmf->prealloc_pte); - spin_unlock(vmf->ptl); - vmf->prealloc_pte = NULL; - } else if (unlikely(pte_alloc(vma->vm_mm, vmf->pmd))) { - return VM_FAULT_OOM; - } -map_pte: - /* - * If a huge pmd materialized under us just retry later. Use - * pmd_trans_unstable() via pmd_devmap_trans_unstable() instead of - * pmd_trans_huge() to ensure the pmd didn't become pmd_trans_huge - * under us and then back to pmd_none, as a result of MADV_DONTNEED - * running immediately after a huge pmd fault in a different thread of - * this mm, in turn leading to a misleading pmd_trans_huge() retval. - * All we have to ensure is that it is a regular pmd that we can walk - * with pte_offset_map() and we can do that through an atomic read in - * C, which is what pmd_trans_unstable() provides. - */ - if (pmd_devmap_trans_unstable(vmf->pmd)) - return VM_FAULT_NOPAGE; - - /* - * At this point we know that our vmf->pmd points to a page of ptes - * and it cannot become pmd_none(), pmd_devmap() or pmd_trans_huge() - * for the duration of the fault. If a racing MADV_DONTNEED runs and - * we zap the ptes pointed to by our vmf->pmd, the vmf->ptl will still - * be valid and we will re-check to make sure the vmf->pte isn't - * pte_none() under vmf->ptl protection when we return to - * alloc_set_pte(). - */ - vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address, - &vmf->ptl); - return 0; -} - #ifdef CONFIG_TRANSPARENT_HUGEPAGE static void deposit_prealloc_pte(struct vm_fault *vmf) { @@ -3717,7 +3657,7 @@ static void deposit_prealloc_pte(struct vm_fault *vmf) vmf->prealloc_pte = NULL; } -static vm_fault_t do_set_pmd(struct vm_fault *vmf, struct page *page) +vm_fault_t do_set_pmd(struct vm_fault *vmf, struct page *page) { struct vm_area_struct *vma = vmf->vma; bool write = vmf->flags & FAULT_FLAG_WRITE; @@ -3775,52 +3715,17 @@ static vm_fault_t do_set_pmd(struct vm_fault *vmf, struct page *page) return ret; } #else -static vm_fault_t do_set_pmd(struct vm_fault *vmf, struct page *page) +vm_fault_t do_set_pmd(struct vm_fault *vmf, struct page *page) { - BUILD_BUG(); - return 0; + return VM_FAULT_FALLBACK; } #endif -/** - * alloc_set_pte - setup new PTE entry for given page and add reverse page - * mapping. If needed, the function allocates page table or use pre-allocated. - * - * @vmf: fault environment - * @page: page to map - * - * Caller must take care of unlocking vmf->ptl, if vmf->pte is non-NULL on - * return. - * - * Target users are page handler itself and implementations of - * vm_ops->map_pages. - * - * Return: %0 on success, %VM_FAULT_ code in case of error. - */ -vm_fault_t alloc_set_pte(struct vm_fault *vmf, struct page *page) +void do_set_pte(struct vm_fault *vmf, struct page *page) { struct vm_area_struct *vma = vmf->vma; bool write = vmf->flags & FAULT_FLAG_WRITE; pte_t entry; - vm_fault_t ret; - - if (pmd_none(*vmf->pmd) && PageTransCompound(page)) { - ret = do_set_pmd(vmf, page); - if (ret != VM_FAULT_FALLBACK) - return ret; - } - - if (!vmf->pte) { - ret = pte_alloc_one_map(vmf); - if (ret) - return ret; - } - - /* Re-check under ptl */ - if (unlikely(!pte_none(*vmf->pte))) { - update_mmu_tlb(vma, vmf->address, vmf->pte); - return VM_FAULT_NOPAGE; - } flush_icache_page(vma, page); entry = mk_pte(page, vma->vm_page_prot); @@ -3837,14 +3742,8 @@ vm_fault_t alloc_set_pte(struct vm_fault *vmf, struct page *page) page_add_file_rmap(page, false); } set_pte_at(vma->vm_mm, vmf->address, vmf->pte, entry); - - /* no need to invalidate: a not-present page won't be cached */ - update_mmu_cache(vma, vmf->address, vmf->pte); - - return 0; } - /** * finish_fault - finish page fault once we have prepared the page to fault * @@ -3862,12 +3761,12 @@ vm_fault_t alloc_set_pte(struct vm_fault *vmf, struct page *page) */ vm_fault_t finish_fault(struct vm_fault *vmf) { + struct vm_area_struct *vma = vmf->vma; struct page *page; - vm_fault_t ret = 0; + vm_fault_t ret; /* Did we COW the page? */ - if ((vmf->flags & FAULT_FLAG_WRITE) && - !(vmf->vma->vm_flags & VM_SHARED)) + if ((vmf->flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED)) page = vmf->cow_page; else page = vmf->page; @@ -3876,12 +3775,38 @@ vm_fault_t finish_fault(struct vm_fault *vmf) * check even for read faults because we might have lost our CoWed * page */ - if (!(vmf->vma->vm_flags & VM_SHARED)) - ret = check_stable_address_space(vmf->vma->vm_mm); - if (!ret) - ret = alloc_set_pte(vmf, page); - if (vmf->pte) - pte_unmap_unlock(vmf->pte, vmf->ptl); + if (!(vma->vm_flags & VM_SHARED)) { + ret = check_stable_address_space(vma->vm_mm); + if (ret) + return ret; + } + + if (pmd_none(*vmf->pmd)) { + if (PageTransCompound(page)) { + ret = do_set_pmd(vmf, page); + if (ret != VM_FAULT_FALLBACK) + return ret; + } + + if (unlikely(pte_alloc(vma->vm_mm, vmf->pmd))) + return VM_FAULT_OOM; + } + + /* See comment in handle_pte_fault() */ + if (pmd_devmap_trans_unstable(vmf->pmd)) + return 0; + + vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, + vmf->address, &vmf->ptl); + ret = 0; + /* Re-check under ptl */ + if (likely(pte_none(*vmf->pte))) + do_set_pte(vmf, page); + else + ret = VM_FAULT_NOPAGE; + + update_mmu_tlb(vma, vmf->address, vmf->pte); + pte_unmap_unlock(vmf->pte, vmf->ptl); return ret; } @@ -3951,13 +3876,12 @@ static vm_fault_t do_fault_around(struct vm_fault *vmf) pgoff_t start_pgoff = vmf->pgoff; pgoff_t end_pgoff; int off; - vm_fault_t ret = 0; nr_pages = READ_ONCE(fault_around_bytes) >> PAGE_SHIFT; mask = ~(nr_pages * PAGE_SIZE - 1) & PAGE_MASK; - vmf->address = max(address & mask, vmf->vma->vm_start); - off = ((address - vmf->address) >> PAGE_SHIFT) & (PTRS_PER_PTE - 1); + address = max(address & mask, vmf->vma->vm_start); + off = ((vmf->address - address) >> PAGE_SHIFT) & (PTRS_PER_PTE - 1); start_pgoff -= off; /* @@ -3965,7 +3889,7 @@ static vm_fault_t do_fault_around(struct vm_fault *vmf) * the vma or nr_pages from start_pgoff, depending what is nearest. */ end_pgoff = start_pgoff - - ((vmf->address >> PAGE_SHIFT) & (PTRS_PER_PTE - 1)) + + ((address >> PAGE_SHIFT) & (PTRS_PER_PTE - 1)) + PTRS_PER_PTE - 1; end_pgoff = min3(end_pgoff, vma_pages(vmf->vma) + vmf->vma->vm_pgoff - 1, start_pgoff + nr_pages - 1); @@ -3973,31 +3897,11 @@ static vm_fault_t do_fault_around(struct vm_fault *vmf) if (pmd_none(*vmf->pmd)) { vmf->prealloc_pte = pte_alloc_one(vmf->vma->vm_mm); if (!vmf->prealloc_pte) - goto out; + return VM_FAULT_OOM; smp_wmb(); /* See comment in __pte_alloc() */ } - vmf->vma->vm_ops->map_pages(vmf, start_pgoff, end_pgoff); - - /* Huge page is mapped? Page fault is solved */ - if (pmd_trans_huge(*vmf->pmd)) { - ret = VM_FAULT_NOPAGE; - goto out; - } - - /* ->map_pages() haven't done anything useful. Cold page cache? */ - if (!vmf->pte) - goto out; - - /* check if the page fault is solved */ - vmf->pte -= (vmf->address >> PAGE_SHIFT) - (address >> PAGE_SHIFT); - if (!pte_none(*vmf->pte)) - ret = VM_FAULT_NOPAGE; - pte_unmap_unlock(vmf->pte, vmf->ptl); -out: - vmf->address = address; - vmf->pte = NULL; - return ret; + return vmf->vma->vm_ops->map_pages(vmf, start_pgoff, end_pgoff); } static vm_fault_t do_read_fault(struct vm_fault *vmf) @@ -4353,7 +4257,18 @@ static vm_fault_t handle_pte_fault(struct vm_fault *vmf) */ vmf->pte = NULL; } else { - /* See comment in pte_alloc_one_map() */ + /* + * If a huge pmd materialized under us just retry later. Use + * pmd_trans_unstable() via pmd_devmap_trans_unstable() instead + * of pmd_trans_huge() to ensure the pmd didn't become + * pmd_trans_huge under us and then back to pmd_none, as a + * result of MADV_DONTNEED running immediately after a huge pmd + * fault in a different thread of this mm, in turn leading to a + * misleading pmd_trans_huge() retval. All we have to ensure is + * that it is a regular pmd that we can walk with + * pte_offset_map() and we can do that through an atomic read + * in C, which is what pmd_trans_unstable() provides. + */ if (pmd_devmap_trans_unstable(vmf->pmd)) return 0; /*