// SPDX-License-Identifier: GPL-2.0-only/* * mm/userfaultfd.c * * Copyright (C) 2015 Red Hat, Inc. */ #include <linux/mm.h>#include <linux/sched/signal.h>#include <linux/pagemap.h>#include <linux/rmap.h>#include <linux/swap.h>#include <linux/swapops.h>#include <linux/userfaultfd_k.h>#include <linux/mmu_notifier.h>#include <linux/hugetlb.h>#include <linux/shmem_fs.h>#include <asm/tlbflush.h>#include "internal.h" static __always_inlinestruct vm_area_struct *find_dst_vma(struct mm_struct *dst_mm, unsigned long dst_start, unsigned long len){ /* * Make sure that the dst range is both valid and fully within a * single existing vma. */ struct vm_area_struct *dst_vma; dst_vma = find_vma(dst_mm, dst_start); if (!dst_vma) return NULL; if (dst_start < dst_vma->vm_start || dst_start + len > dst_vma->vm_end) return NULL; /* * Check the vma is registered in uffd, this is required to * enforce the VM_MAYWRITE check done at uffd registration * time. */ if (!dst_vma->vm_userfaultfd_ctx.ctx) return NULL; return dst_vma;} static int mcopy_atomic_pte(struct mm_struct *dst_mm, pmd_t *dst_pmd, struct vm_area_struct *dst_vma, unsigned long dst_addr, unsigned long src_addr, struct page **pagep, bool wp_copy){ pte_t _dst_pte, *dst_pte; spinlock_t *ptl; void *page_kaddr; int ret; struct page *page; pgoff_t offset, max_off; struct inode *inode; if (!*pagep) { ret = -ENOMEM; page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, dst_vma, dst_addr); if (!page) goto out; page_kaddr = kmap_atomic(page); ret = copy_from_user(page_kaddr, (const void __user *) src_addr, PAGE_SIZE); kunmap_atomic(page_kaddr); /* fallback to copy_from_user outside mmap_lock */ if (unlikely(ret)) { ret = -ENOENT; *pagep = page; /* don't free the page */ goto out; } } else { page = *pagep; *pagep = NULL; } /* * The memory barrier inside __SetPageUptodate makes sure that * preceding stores to the page contents become visible before * the set_pte_at() write. */ __SetPageUptodate(page); ret = -ENOMEM; if (mem_cgroup_charge(page, dst_mm, GFP_KERNEL)) goto out_release; _dst_pte = pte_mkdirty(mk_pte(page, dst_vma->vm_page_prot)); if (dst_vma->vm_flags & VM_WRITE) { if (wp_copy) _dst_pte = pte_mkuffd_wp(_dst_pte); else _dst_pte = pte_mkwrite(_dst_pte); } dst_pte = pte_offset_map_lock(dst_mm, dst_pmd, dst_addr, &ptl); if (dst_vma->vm_file) { /* the shmem MAP_PRIVATE case requires checking the i_size */ inode = dst_vma->vm_file->f_inode; offset = linear_page_index(dst_vma, dst_addr); max_off = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE); ret = -EFAULT; if (unlikely(offset >= max_off)) goto out_release_uncharge_unlock; } ret = -EEXIST; if (!pte_none(*dst_pte)) goto out_release_uncharge_unlock; inc_mm_counter(dst_mm, MM_ANONPAGES); page_add_new_anon_rmap(page, dst_vma, dst_addr, false); lru_cache_add_inactive_or_unevictable(page, dst_vma); set_pte_at(dst_mm, dst_addr, dst_pte, _dst_pte); /* No need to invalidate - it was non-present before */ update_mmu_cache(dst_vma, dst_addr, dst_pte); pte_unmap_unlock(dst_pte, ptl); ret = 0;out: return ret;out_release_uncharge_unlock: pte_unmap_unlock(dst_pte, ptl);out_release: put_page(page); goto out;} static int mfill_zeropage_pte(struct mm_struct *dst_mm, pmd_t *dst_pmd, struct vm_area_struct *dst_vma, unsigned long dst_addr){ pte_t _dst_pte, *dst_pte; spinlock_t *ptl; int ret; pgoff_t offset, max_off; struct inode *inode; _dst_pte = pte_mkspecial(pfn_pte(my_zero_pfn(dst_addr), dst_vma->vm_page_prot)); dst_pte = pte_offset_map_lock(dst_mm, dst_pmd, dst_addr, &ptl); if (dst_vma->vm_file) { /* the shmem MAP_PRIVATE case requires checking the i_size */ inode = dst_vma->vm_file->f_inode; offset = linear_page_index(dst_vma, dst_addr); max_off = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE); ret = -EFAULT; if (unlikely(offset >= max_off)) goto out_unlock; } ret = -EEXIST; if (!pte_none(*dst_pte)) goto out_unlock; set_pte_at(dst_mm, dst_addr, dst_pte, _dst_pte); /* No need to invalidate - it was non-present before */ update_mmu_cache(dst_vma, dst_addr, dst_pte); ret = 0;out_unlock: pte_unmap_unlock(dst_pte, ptl); return ret;} static pmd_t *mm_alloc_pmd(struct mm_struct *mm, unsigned long address){ pgd_t *pgd; p4d_t *p4d; pud_t *pud; pgd = pgd_offset(mm, address); p4d = p4d_alloc(mm, pgd, address); if (!p4d) return NULL; pud = pud_alloc(mm, p4d, address); if (!pud) return NULL; /* * Note that we didn't run this because the pmd was * missing, the *pmd may be already established and in * turn it may also be a trans_huge_pmd. */ return pmd_alloc(mm, pud, address);} #ifdef CONFIG_HUGETLB_PAGE/* * __mcopy_atomic processing for HUGETLB vmas. Note that this routine is * called with mmap_lock held, it will release mmap_lock before returning. */static __always_inline ssize_t __mcopy_atomic_hugetlb(struct mm_struct *dst_mm, struct vm_area_struct *dst_vma, unsigned long dst_start, unsigned long src_start, unsigned long len, bool zeropage){ int vm_alloc_shared = dst_vma->vm_flags & VM_SHARED; int vm_shared = dst_vma->vm_flags & VM_SHARED; ssize_t err; pte_t *dst_pte; unsigned long src_addr, dst_addr; long copied; struct page *page; unsigned long vma_hpagesize; pgoff_t idx; u32 hash; struct address_space *mapping; /* * There is no default zero huge page for all huge page sizes as * supported by hugetlb. A PMD_SIZE huge pages may exist as used * by THP. Since we can not reliably insert a zero page, this * feature is not supported. */ if (zeropage) { mmap_read_unlock(dst_mm); return -EINVAL; } src_addr = src_start; dst_addr = dst_start; copied = 0; page = NULL; vma_hpagesize = vma_kernel_pagesize(dst_vma); /* * Validate alignment based on huge page size */ err = -EINVAL; if (dst_start & (vma_hpagesize - 1) || len & (vma_hpagesize - 1)) goto out_unlock; retry: /* * On routine entry dst_vma is set. If we had to drop mmap_lock and * retry, dst_vma will be set to NULL and we must lookup again. */ if (!dst_vma) { err = -ENOENT; dst_vma = find_dst_vma(dst_mm, dst_start, len); if (!dst_vma || !is_vm_hugetlb_page(dst_vma)) goto out_unlock; err = -EINVAL; if (vma_hpagesize != vma_kernel_pagesize(dst_vma)) goto out_unlock; vm_shared = dst_vma->vm_flags & VM_SHARED; } /* * If not shared, ensure the dst_vma has a anon_vma. */ err = -ENOMEM; if (!vm_shared) { if (unlikely(anon_vma_prepare(dst_vma))) goto out_unlock; } while (src_addr < src_start + len) { pte_t dst_pteval; BUG_ON(dst_addr >= dst_start + len); /* * Serialize via i_mmap_rwsem and hugetlb_fault_mutex. * i_mmap_rwsem ensures the dst_pte remains valid even * in the case of shared pmds. fault mutex prevents * races with other faulting threads. */ mapping = dst_vma->vm_file->f_mapping; i_mmap_lock_read(mapping); idx = linear_page_index(dst_vma, dst_addr); hash = hugetlb_fault_mutex_hash(mapping, idx); mutex_lock(&hugetlb_fault_mutex_table[hash]); err = -ENOMEM; dst_pte = huge_pte_alloc(dst_mm, dst_addr, vma_hpagesize); if (!dst_pte) { mutex_unlock(&hugetlb_fault_mutex_table[hash]); i_mmap_unlock_read(mapping); goto out_unlock; } err = -EEXIST; dst_pteval = huge_ptep_get(dst_pte); if (!huge_pte_none(dst_pteval)) { mutex_unlock(&hugetlb_fault_mutex_table[hash]); i_mmap_unlock_read(mapping); goto out_unlock; } err = hugetlb_mcopy_atomic_pte(dst_mm, dst_pte, dst_vma, dst_addr, src_addr, &page); mutex_unlock(&hugetlb_fault_mutex_table[hash]); i_mmap_unlock_read(mapping); vm_alloc_shared = vm_shared; cond_resched(); if (unlikely(err == -ENOENT)) { mmap_read_unlock(dst_mm); BUG_ON(!page); err = copy_huge_page_from_user(page, (const void __user *)src_addr, vma_hpagesize / PAGE_SIZE, true); if (unlikely(err)) { err = -EFAULT; goto out; } mmap_read_lock(dst_mm); dst_vma = NULL; goto retry; } else BUG_ON(page); if (!err) { dst_addr += vma_hpagesize; src_addr += vma_hpagesize; copied += vma_hpagesize; if (fatal_signal_pending(current)) err = -EINTR; } if (err) break; } out_unlock: mmap_read_unlock(dst_mm);out: if (page) { /* * We encountered an error and are about to free a newly * allocated huge page. * * Reservation handling is very subtle, and is different for * private and shared mappings. See the routine * restore_reserve_on_error for details. Unfortunately, we * can not call restore_reserve_on_error now as it would * require holding mmap_lock. * * If a reservation for the page existed in the reservation * map of a private mapping, the map was modified to indicate * the reservation was consumed when the page was allocated. * We clear the PagePrivate flag now so that the global * reserve count will not be incremented in free_huge_page. * The reservation map will still indicate the reservation * was consumed and possibly prevent later page allocation. * This is better than leaking a global reservation. If no * reservation existed, it is still safe to clear PagePrivate * as no adjustments to reservation counts were made during * allocation. * * The reservation map for shared mappings indicates which * pages have reservations. When a huge page is allocated * for an address with a reservation, no change is made to * the reserve map. In this case PagePrivate will be set * to indicate that the global reservation count should be * incremented when the page is freed. This is the desired * behavior. However, when a huge page is allocated for an * address without a reservation a reservation entry is added * to the reservation map, and PagePrivate will not be set. * When the page is freed, the global reserve count will NOT * be incremented and it will appear as though we have leaked * reserved page. In this case, set PagePrivate so that the * global reserve count will be incremented to match the * reservation map entry which was created. * * Note that vm_alloc_shared is based on the flags of the vma * for which the page was originally allocated. dst_vma could * be different or NULL on error. */ if (vm_alloc_shared) SetPagePrivate(page); else ClearPagePrivate(page); put_page(page); } BUG_ON(copied < 0); BUG_ON(err > 0); BUG_ON(!copied && !err); return copied ? copied : err;}#else /* !CONFIG_HUGETLB_PAGE *//* fail at build time if gcc attempts to use this */extern ssize_t __mcopy_atomic_hugetlb(struct mm_struct *dst_mm, struct vm_area_struct *dst_vma, unsigned long dst_start, unsigned long src_start, unsigned long len, bool zeropage);#endif /* CONFIG_HUGETLB_PAGE */ static __always_inline ssize_t mfill_atomic_pte(struct mm_struct *dst_mm, pmd_t *dst_pmd, struct vm_area_struct *dst_vma, unsigned long dst_addr, unsigned long src_addr, struct page **page, bool zeropage, bool wp_copy){ ssize_t err; /* * The normal page fault path for a shmem will invoke the * fault, fill the hole in the file and COW it right away. The * result generates plain anonymous memory. So when we are * asked to fill an hole in a MAP_PRIVATE shmem mapping, we'll * generate anonymous memory directly without actually filling * the hole. For the MAP_PRIVATE case the robustness check * only happens in the pagetable (to verify it's still none) * and not in the radix tree. */ if (!(dst_vma->vm_flags & VM_SHARED)) { if (!zeropage) err = mcopy_atomic_pte(dst_mm, dst_pmd, dst_vma, dst_addr, src_addr, page, wp_copy); else err = mfill_zeropage_pte(dst_mm, dst_pmd, dst_vma, dst_addr); } else { VM_WARN_ON_ONCE(wp_copy); if (!zeropage) err = shmem_mcopy_atomic_pte(dst_mm, dst_pmd, dst_vma, dst_addr, src_addr, page); else err = shmem_mfill_zeropage_pte(dst_mm, dst_pmd, dst_vma, dst_addr); } return err;} static __always_inline ssize_t __mcopy_atomic(struct mm_struct *dst_mm, unsigned long dst_start, unsigned long src_start, unsigned long len, bool zeropage, bool *mmap_changing, __u64 mode){ struct vm_area_struct *dst_vma; ssize_t err; pmd_t *dst_pmd; unsigned long src_addr, dst_addr; long copied; struct page *page; bool wp_copy; /* * Sanitize the command parameters: */ BUG_ON(dst_start & ~PAGE_MASK); BUG_ON(len & ~PAGE_MASK); /* Does the address range wrap, or is the span zero-sized? */ BUG_ON(src_start + len <= src_start); BUG_ON(dst_start + len <= dst_start); src_addr = src_start; dst_addr = dst_start; copied = 0; page = NULL;retry: mmap_read_lock(dst_mm); /* * If memory mappings are changing because of non-cooperative * operation (e.g. mremap) running in parallel, bail out and * request the user to retry later */ err = -EAGAIN; if (mmap_changing && READ_ONCE(*mmap_changing)) goto out_unlock; /* * Make sure the vma is not shared, that the dst range isLines 1–500 of 691. Load more
// SPDX-License-Identifier: GPL-2.0-only /* * mm/userfaultfd.c * * Copyright (C) 2015 Red Hat, Inc. */ #include <linux/mm.h> #include <linux/sched/signal.h> #include <linux/pagemap.h> #include <linux/rmap.h> #include <linux/swap.h> #include <linux/swapops.h> #include <linux/userfaultfd_k.h> #include <linux/mmu_notifier.h> #include <linux/hugetlb.h> #include <linux/shmem_fs.h> #include <asm/tlbflush.h> #include "internal.h" static __always_inline struct vm_area_struct *find_dst_vma(struct mm_struct *dst_mm, unsigned long dst_start, unsigned long len) { /* * Make sure that the dst range is both valid and fully within a * single existing vma. */ struct vm_area_struct *dst_vma; dst_vma = find_vma(dst_mm, dst_start); if (!dst_vma) return NULL; if (dst_start < dst_vma->vm_start || dst_start + len > dst_vma->vm_end) return NULL; /* * Check the vma is registered in uffd, this is required to * enforce the VM_MAYWRITE check done at uffd registration * time. */ if (!dst_vma->vm_userfaultfd_ctx.ctx) return NULL; return dst_vma; } static int mcopy_atomic_pte(struct mm_struct *dst_mm, pmd_t *dst_pmd, struct vm_area_struct *dst_vma, unsigned long dst_addr, unsigned long src_addr, struct page **pagep, bool wp_copy) { pte_t _dst_pte, *dst_pte; spinlock_t *ptl; void *page_kaddr; int ret; struct page *page; pgoff_t offset, max_off; struct inode *inode; if (!*pagep) { ret = -ENOMEM; page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, dst_vma, dst_addr); if (!page) goto out; page_kaddr = kmap_atomic(page); ret = copy_from_user(page_kaddr, (const void __user *) src_addr, PAGE_SIZE); kunmap_atomic(page_kaddr); /* fallback to copy_from_user outside mmap_lock */ if (unlikely(ret)) { ret = -ENOENT; *pagep = page; /* don't free the page */ goto out; } } else { page = *pagep; *pagep = NULL; } /* * The memory barrier inside __SetPageUptodate makes sure that * preceding stores to the page contents become visible before * the set_pte_at() write. */ __SetPageUptodate(page); ret = -ENOMEM; if (mem_cgroup_charge(page, dst_mm, GFP_KERNEL)) goto out_release; _dst_pte = pte_mkdirty(mk_pte(page, dst_vma->vm_page_prot)); if (dst_vma->vm_flags & VM_WRITE) { if (wp_copy) _dst_pte = pte_mkuffd_wp(_dst_pte); else _dst_pte = pte_mkwrite(_dst_pte); } dst_pte = pte_offset_map_lock(dst_mm, dst_pmd, dst_addr, &ptl); if (dst_vma->vm_file) { /* the shmem MAP_PRIVATE case requires checking the i_size */ inode = dst_vma->vm_file->f_inode; offset = linear_page_index(dst_vma, dst_addr); max_off = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE); ret = -EFAULT; if (unlikely(offset >= max_off)) goto out_release_uncharge_unlock; } ret = -EEXIST; if (!pte_none(*dst_pte)) goto out_release_uncharge_unlock; inc_mm_counter(dst_mm, MM_ANONPAGES); page_add_new_anon_rmap(page, dst_vma, dst_addr, false); lru_cache_add_inactive_or_unevictable(page, dst_vma); set_pte_at(dst_mm, dst_addr, dst_pte, _dst_pte); /* No need to invalidate - it was non-present before */ update_mmu_cache(dst_vma, dst_addr, dst_pte); pte_unmap_unlock(dst_pte, ptl); ret = 0; out: return ret; out_release_uncharge_unlock: pte_unmap_unlock(dst_pte, ptl); out_release: put_page(page); goto out; } static int mfill_zeropage_pte(struct mm_struct *dst_mm, pmd_t *dst_pmd, struct vm_area_struct *dst_vma, unsigned long dst_addr) { pte_t _dst_pte, *dst_pte; spinlock_t *ptl; int ret; pgoff_t offset, max_off; struct inode *inode; _dst_pte = pte_mkspecial(pfn_pte(my_zero_pfn(dst_addr), dst_vma->vm_page_prot)); dst_pte = pte_offset_map_lock(dst_mm, dst_pmd, dst_addr, &ptl); if (dst_vma->vm_file) { /* the shmem MAP_PRIVATE case requires checking the i_size */ inode = dst_vma->vm_file->f_inode; offset = linear_page_index(dst_vma, dst_addr); max_off = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE); ret = -EFAULT; if (unlikely(offset >= max_off)) goto out_unlock; } ret = -EEXIST; if (!pte_none(*dst_pte)) goto out_unlock; set_pte_at(dst_mm, dst_addr, dst_pte, _dst_pte); /* No need to invalidate - it was non-present before */ update_mmu_cache(dst_vma, dst_addr, dst_pte); ret = 0; out_unlock: pte_unmap_unlock(dst_pte, ptl); return ret; } static pmd_t *mm_alloc_pmd(struct mm_struct *mm, unsigned long address) { pgd_t *pgd; p4d_t *p4d; pud_t *pud; pgd = pgd_offset(mm, address); p4d = p4d_alloc(mm, pgd, address); if (!p4d) return NULL; pud = pud_alloc(mm, p4d, address); if (!pud) return NULL; /* * Note that we didn't run this because the pmd was * missing, the *pmd may be already established and in * turn it may also be a trans_huge_pmd. */ return pmd_alloc(mm, pud, address); } #ifdef CONFIG_HUGETLB_PAGE /* * __mcopy_atomic processing for HUGETLB vmas. Note that this routine is * called with mmap_lock held, it will release mmap_lock before returning. */ static __always_inline ssize_t __mcopy_atomic_hugetlb(struct mm_struct *dst_mm, struct vm_area_struct *dst_vma, unsigned long dst_start, unsigned long src_start, unsigned long len, bool zeropage) { int vm_alloc_shared = dst_vma->vm_flags & VM_SHARED; int vm_shared = dst_vma->vm_flags & VM_SHARED; ssize_t err; pte_t *dst_pte; unsigned long src_addr, dst_addr; long copied; struct page *page; unsigned long vma_hpagesize; pgoff_t idx; u32 hash; struct address_space *mapping; /* * There is no default zero huge page for all huge page sizes as * supported by hugetlb. A PMD_SIZE huge pages may exist as used * by THP. Since we can not reliably insert a zero page, this * feature is not supported. */ if (zeropage) { mmap_read_unlock(dst_mm); return -EINVAL; } src_addr = src_start; dst_addr = dst_start; copied = 0; page = NULL; vma_hpagesize = vma_kernel_pagesize(dst_vma); /* * Validate alignment based on huge page size */ err = -EINVAL; if (dst_start & (vma_hpagesize - 1) || len & (vma_hpagesize - 1)) goto out_unlock; retry: /* * On routine entry dst_vma is set. If we had to drop mmap_lock and * retry, dst_vma will be set to NULL and we must lookup again. */ if (!dst_vma) { err = -ENOENT; dst_vma = find_dst_vma(dst_mm, dst_start, len); if (!dst_vma || !is_vm_hugetlb_page(dst_vma)) goto out_unlock; err = -EINVAL; if (vma_hpagesize != vma_kernel_pagesize(dst_vma)) goto out_unlock; vm_shared = dst_vma->vm_flags & VM_SHARED; } /* * If not shared, ensure the dst_vma has a anon_vma. */ err = -ENOMEM; if (!vm_shared) { if (unlikely(anon_vma_prepare(dst_vma))) goto out_unlock; } while (src_addr < src_start + len) { pte_t dst_pteval; BUG_ON(dst_addr >= dst_start + len); /* * Serialize via i_mmap_rwsem and hugetlb_fault_mutex. * i_mmap_rwsem ensures the dst_pte remains valid even * in the case of shared pmds. fault mutex prevents * races with other faulting threads. */ mapping = dst_vma->vm_file->f_mapping; i_mmap_lock_read(mapping); idx = linear_page_index(dst_vma, dst_addr); hash = hugetlb_fault_mutex_hash(mapping, idx); mutex_lock(&hugetlb_fault_mutex_table[hash]); err = -ENOMEM; dst_pte = huge_pte_alloc(dst_mm, dst_addr, vma_hpagesize); if (!dst_pte) { mutex_unlock(&hugetlb_fault_mutex_table[hash]); i_mmap_unlock_read(mapping); goto out_unlock; } err = -EEXIST; dst_pteval = huge_ptep_get(dst_pte); if (!huge_pte_none(dst_pteval)) { mutex_unlock(&hugetlb_fault_mutex_table[hash]); i_mmap_unlock_read(mapping); goto out_unlock; } err = hugetlb_mcopy_atomic_pte(dst_mm, dst_pte, dst_vma, dst_addr, src_addr, &page); mutex_unlock(&hugetlb_fault_mutex_table[hash]); i_mmap_unlock_read(mapping); vm_alloc_shared = vm_shared; cond_resched(); if (unlikely(err == -ENOENT)) { mmap_read_unlock(dst_mm); BUG_ON(!page); err = copy_huge_page_from_user(page, (const void __user *)src_addr, vma_hpagesize / PAGE_SIZE, true); if (unlikely(err)) { err = -EFAULT; goto out; } mmap_read_lock(dst_mm); dst_vma = NULL; goto retry; } else BUG_ON(page); if (!err) { dst_addr += vma_hpagesize; src_addr += vma_hpagesize; copied += vma_hpagesize; if (fatal_signal_pending(current)) err = -EINTR; } if (err) break; } out_unlock: mmap_read_unlock(dst_mm); out: if (page) { /* * We encountered an error and are about to free a newly * allocated huge page. * * Reservation handling is very subtle, and is different for * private and shared mappings. See the routine * restore_reserve_on_error for details. Unfortunately, we * can not call restore_reserve_on_error now as it would * require holding mmap_lock. * * If a reservation for the page existed in the reservation * map of a private mapping, the map was modified to indicate * the reservation was consumed when the page was allocated. * We clear the PagePrivate flag now so that the global * reserve count will not be incremented in free_huge_page. * The reservation map will still indicate the reservation * was consumed and possibly prevent later page allocation. * This is better than leaking a global reservation. If no * reservation existed, it is still safe to clear PagePrivate * as no adjustments to reservation counts were made during * allocation. * * The reservation map for shared mappings indicates which * pages have reservations. When a huge page is allocated * for an address with a reservation, no change is made to * the reserve map. In this case PagePrivate will be set * to indicate that the global reservation count should be * incremented when the page is freed. This is the desired * behavior. However, when a huge page is allocated for an * address without a reservation a reservation entry is added * to the reservation map, and PagePrivate will not be set. * When the page is freed, the global reserve count will NOT * be incremented and it will appear as though we have leaked * reserved page. In this case, set PagePrivate so that the * global reserve count will be incremented to match the * reservation map entry which was created. * * Note that vm_alloc_shared is based on the flags of the vma * for which the page was originally allocated. dst_vma could * be different or NULL on error. */ if (vm_alloc_shared) SetPagePrivate(page); else ClearPagePrivate(page); put_page(page); } BUG_ON(copied < 0); BUG_ON(err > 0); BUG_ON(!copied && !err); return copied ? copied : err; } #else /* !CONFIG_HUGETLB_PAGE */ /* fail at build time if gcc attempts to use this */ extern ssize_t __mcopy_atomic_hugetlb(struct mm_struct *dst_mm, struct vm_area_struct *dst_vma, unsigned long dst_start, unsigned long src_start, unsigned long len, bool zeropage); #endif /* CONFIG_HUGETLB_PAGE */ static __always_inline ssize_t mfill_atomic_pte(struct mm_struct *dst_mm, pmd_t *dst_pmd, struct vm_area_struct *dst_vma, unsigned long dst_addr, unsigned long src_addr, struct page **page, bool zeropage, bool wp_copy) { ssize_t err; /* * The normal page fault path for a shmem will invoke the * fault, fill the hole in the file and COW it right away. The * result generates plain anonymous memory. So when we are * asked to fill an hole in a MAP_PRIVATE shmem mapping, we'll * generate anonymous memory directly without actually filling * the hole. For the MAP_PRIVATE case the robustness check * only happens in the pagetable (to verify it's still none) * and not in the radix tree. */ if (!(dst_vma->vm_flags & VM_SHARED)) { if (!zeropage) err = mcopy_atomic_pte(dst_mm, dst_pmd, dst_vma, dst_addr, src_addr, page, wp_copy); else err = mfill_zeropage_pte(dst_mm, dst_pmd, dst_vma, dst_addr); } else { VM_WARN_ON_ONCE(wp_copy); if (!zeropage) err = shmem_mcopy_atomic_pte(dst_mm, dst_pmd, dst_vma, dst_addr, src_addr, page); else err = shmem_mfill_zeropage_pte(dst_mm, dst_pmd, dst_vma, dst_addr); } return err; } static __always_inline ssize_t __mcopy_atomic(struct mm_struct *dst_mm, unsigned long dst_start, unsigned long src_start, unsigned long len, bool zeropage, bool *mmap_changing, __u64 mode) { struct vm_area_struct *dst_vma; ssize_t err; pmd_t *dst_pmd; unsigned long src_addr, dst_addr; long copied; struct page *page; bool wp_copy; /* * Sanitize the command parameters: */ BUG_ON(dst_start & ~PAGE_MASK); BUG_ON(len & ~PAGE_MASK); /* Does the address range wrap, or is the span zero-sized? */ BUG_ON(src_start + len <= src_start); BUG_ON(dst_start + len <= dst_start); src_addr = src_start; dst_addr = dst_start; copied = 0; page = NULL; retry: mmap_read_lock(dst_mm); /* * If memory mappings are changing because of non-cooperative * operation (e.g. mremap) running in parallel, bail out and * request the user to retry later */ err = -EAGAIN; if (mmap_changing && READ_ONCE(*mmap_changing)) goto out_unlock; /* * Make sure the vma is not shared, that the dst range is