/* SPDX-License-Identifier: GPL-2.0 */
/*
 * Official Linux v6.18: include/linux/mm_types.h
 * Complete struct; source lines 813-917.
 * Body unchanged. Kernel dependencies and configuration are required.
 * Source URL, SHA, commit, and license: provenance.json; GPL-2.0.txt.
 */

struct vm_area_struct {
	/* The first cache line has the info for VMA tree walking. */

	union {
		struct {
			/* VMA covers [vm_start; vm_end) addresses within mm */
			unsigned long vm_start;
			unsigned long vm_end;
		};
		freeptr_t vm_freeptr; /* Pointer used by SLAB_TYPESAFE_BY_RCU */
	};

	/*
	 * The address space we belong to.
	 * Unstable RCU readers are allowed to read this.
	 */
	struct mm_struct *vm_mm;
	pgprot_t vm_page_prot;          /* Access permissions of this VMA. */

	/*
	 * Flags, see mm.h.
	 * To modify use vm_flags_{init|reset|set|clear|mod} functions.
	 */
	union {
		const vm_flags_t vm_flags;
		vm_flags_t __private __vm_flags;
	};

#ifdef CONFIG_PER_VMA_LOCK
	/*
	 * Can only be written (using WRITE_ONCE()) while holding both:
	 *  - mmap_lock (in write mode)
	 *  - vm_refcnt bit at VMA_LOCK_OFFSET is set
	 * Can be read reliably while holding one of:
	 *  - mmap_lock (in read or write mode)
	 *  - vm_refcnt bit at VMA_LOCK_OFFSET is set or vm_refcnt > 1
	 * Can be read unreliably (using READ_ONCE()) for pessimistic bailout
	 * while holding nothing (except RCU to keep the VMA struct allocated).
	 *
	 * This sequence counter is explicitly allowed to overflow; sequence
	 * counter reuse can only lead to occasional unnecessary use of the
	 * slowpath.
	 */
	unsigned int vm_lock_seq;
#endif
	/*
	 * A file's MAP_PRIVATE vma can be in both i_mmap tree and anon_vma
	 * list, after a COW of one of the file pages.	A MAP_SHARED vma
	 * can only be in the i_mmap tree.  An anonymous MAP_PRIVATE, stack
	 * or brk vma (with NULL file) can only be in an anon_vma list.
	 */
	struct list_head anon_vma_chain; /* Serialized by mmap_lock &
					  * page_table_lock */
	struct anon_vma *anon_vma;	/* Serialized by page_table_lock */

	/* Function pointers to deal with this struct. */
	const struct vm_operations_struct *vm_ops;

	/* Information about our backing store: */
	unsigned long vm_pgoff;		/* Offset (within vm_file) in PAGE_SIZE
					   units */
	struct file * vm_file;		/* File we map to (can be NULL). */
	void * vm_private_data;		/* was vm_pte (shared mem) */

#ifdef CONFIG_SWAP
	atomic_long_t swap_readahead_info;
#endif
#ifndef CONFIG_MMU
	struct vm_region *vm_region;	/* NOMMU mapping region */
#endif
#ifdef CONFIG_NUMA
	struct mempolicy *vm_policy;	/* NUMA policy for the VMA */
#endif
#ifdef CONFIG_NUMA_BALANCING
	struct vma_numab_state *numab_state;	/* NUMA Balancing state */
#endif
#ifdef CONFIG_PER_VMA_LOCK
	/* Unstable RCU readers are allowed to read this. */
	refcount_t vm_refcnt ____cacheline_aligned_in_smp;
#ifdef CONFIG_DEBUG_LOCK_ALLOC
	struct lockdep_map vmlock_dep_map;
#endif
#endif
	/*
	 * For areas with an address space and backing store,
	 * linkage into the address_space->i_mmap interval tree.
	 *
	 */
	struct {
		struct rb_node rb;
		unsigned long rb_subtree_last;
	} shared;
#ifdef CONFIG_ANON_VMA_NAME
	/*
	 * For private and shared anonymous mappings, a pointer to a null
	 * terminated string containing the name given to the vma, or NULL if
	 * unnamed. Serialized by mmap_lock. Use anon_vma_name to access.
	 */
	struct anon_vma_name *anon_name;
#endif
	struct vm_userfaultfd_ctx vm_userfaultfd_ctx;
#ifdef __HAVE_PFNMAP_TRACKING
	struct pfnmap_track_ctx *pfnmap_track_ctx;
#endif
} __randomize_layout;