diff options
Diffstat (limited to 'mm/vma_init.c')
| -rw-r--r-- | mm/vma_init.c | 151 |
1 files changed, 151 insertions, 0 deletions
diff --git a/mm/vma_init.c b/mm/vma_init.c new file mode 100644 index 000000000000..8e53c7943561 --- /dev/null +++ b/mm/vma_init.c @@ -0,0 +1,151 @@ +// SPDX-License-Identifier: GPL-2.0-or-later + +/* + * Functions for initialisaing, allocating, freeing and duplicating VMAs. Shared + * between CONFIG_MMU and non-CONFIG_MMU kernel configurations. + */ + +#include "vma_internal.h" +#include "vma.h" + +/* SLAB cache for vm_area_struct structures */ +static struct kmem_cache *vm_area_cachep; + +void __init vma_state_init(void) +{ + struct kmem_cache_args args = { + .use_freeptr_offset = true, + .freeptr_offset = offsetof(struct vm_area_struct, vm_freeptr), + }; + + vm_area_cachep = kmem_cache_create("vm_area_struct", + sizeof(struct vm_area_struct), &args, + SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_TYPESAFE_BY_RCU| + SLAB_ACCOUNT); +} + +struct vm_area_struct *vm_area_alloc(struct mm_struct *mm) +{ + struct vm_area_struct *vma; + + vma = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL); + if (!vma) + return NULL; + + vma_init(vma, mm); + + return vma; +} + +static void vm_area_init_from(const struct vm_area_struct *src, + struct vm_area_struct *dest) +{ + dest->vm_mm = src->vm_mm; + dest->vm_ops = src->vm_ops; + dest->vm_start = src->vm_start; + dest->vm_end = src->vm_end; + dest->anon_vma = src->anon_vma; + dest->vm_pgoff = src->vm_pgoff; + dest->vm_file = src->vm_file; + dest->vm_private_data = src->vm_private_data; + vm_flags_init(dest, src->vm_flags); + memcpy(&dest->vm_page_prot, &src->vm_page_prot, + sizeof(dest->vm_page_prot)); + /* + * src->shared.rb may be modified concurrently when called from + * dup_mmap(), but the clone will reinitialize it. + */ + data_race(memcpy(&dest->shared, &src->shared, sizeof(dest->shared))); + memcpy(&dest->vm_userfaultfd_ctx, &src->vm_userfaultfd_ctx, + sizeof(dest->vm_userfaultfd_ctx)); +#ifdef CONFIG_ANON_VMA_NAME + dest->anon_name = src->anon_name; +#endif +#ifdef CONFIG_SWAP + memcpy(&dest->swap_readahead_info, &src->swap_readahead_info, + sizeof(dest->swap_readahead_info)); +#endif +#ifndef CONFIG_MMU + dest->vm_region = src->vm_region; +#endif +#ifdef CONFIG_NUMA + dest->vm_policy = src->vm_policy; +#endif +#ifdef __HAVE_PFNMAP_TRACKING + dest->pfnmap_track_ctx = NULL; +#endif +} + +#ifdef __HAVE_PFNMAP_TRACKING +static inline int vma_pfnmap_track_ctx_dup(struct vm_area_struct *orig, + struct vm_area_struct *new) +{ + struct pfnmap_track_ctx *ctx = orig->pfnmap_track_ctx; + + if (likely(!ctx)) + return 0; + + /* + * We don't expect to ever hit this. If ever required, we would have + * to duplicate the tracking. + */ + if (unlikely(kref_read(&ctx->kref) >= REFCOUNT_MAX)) + return -ENOMEM; + kref_get(&ctx->kref); + new->pfnmap_track_ctx = ctx; + return 0; +} + +static inline void vma_pfnmap_track_ctx_release(struct vm_area_struct *vma) +{ + struct pfnmap_track_ctx *ctx = vma->pfnmap_track_ctx; + + if (likely(!ctx)) + return; + + kref_put(&ctx->kref, pfnmap_track_ctx_release); + vma->pfnmap_track_ctx = NULL; +} +#else +static inline int vma_pfnmap_track_ctx_dup(struct vm_area_struct *orig, + struct vm_area_struct *new) +{ + return 0; +} +static inline void vma_pfnmap_track_ctx_release(struct vm_area_struct *vma) +{ +} +#endif + +struct vm_area_struct *vm_area_dup(struct vm_area_struct *orig) +{ + struct vm_area_struct *new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL); + + if (!new) + return NULL; + + ASSERT_EXCLUSIVE_WRITER(orig->vm_flags); + ASSERT_EXCLUSIVE_WRITER(orig->vm_file); + vm_area_init_from(orig, new); + + if (vma_pfnmap_track_ctx_dup(orig, new)) { + kmem_cache_free(vm_area_cachep, new); + return NULL; + } + vma_lock_init(new, true); + INIT_LIST_HEAD(&new->anon_vma_chain); + vma_numab_state_init(new); + dup_anon_vma_name(orig, new); + + return new; +} + +void vm_area_free(struct vm_area_struct *vma) +{ + /* The vma should be detached while being destroyed. */ + vma_assert_detached(vma); + vma_numab_state_free(vma); + free_anon_vma_name(vma); + vma_pfnmap_track_ctx_release(vma); + kmem_cache_free(vm_area_cachep, vma); +} |