Message-ID: <acygwc7cwbwpl6imyzeupkqdfba7gu6grs25ekrscvmncmbi54@dnlwlmwlz7lb>
Date: Mon, 9 Feb 2026 19:03:22 +0000
From: "Liam R. Howlett" <Liam.Howlett@...cle.com>
To: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>,
        Jarkko Sakkinen <jarkko@...nel.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Thomas Gleixner <tglx@...nel.org>, Ingo Molnar <mingo@...hat.com>,
        Borislav Petkov <bp@...en8.de>, x86@...nel.org,
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        Yury Norov <yury.norov@...il.com>,
        Rasmus Villemoes <linux@...musvillemoes.dk>, linux-sgx@...r.kernel.org,
        linux-kernel@...r.kernel.org, nvdimm@...ts.linux.dev,
        linux-cxl@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        intel-gfx@...ts.freedesktop.org, linux-fsdevel@...r.kernel.org,
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        Jason Gunthorpe <jgg@...dia.com>
Subject: Re: [PATCH v2 06/13] mm: update hugetlbfs to use VMA flags on
 mmap_prepare

* Lorenzo Stoakes <lorenzo.stoakes@...cle.com> [260122 16:06]:
> In order to update all mmap_prepare users to utilising the new VMA flags
> type vma_flags_t and associated helper functions, we start by updating
> hugetlbfs which has a lot of additional logic that requires updating to
> make this change.
> 
> This is laying the groundwork for eliminating the vm_flags_t from struct
> vm_area_desc and using vma_flags_t only, which further lays the ground for
> removing the deprecated vm_flags_t type altogether.
> 
> No functional changes intended.
> 
> Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>

Reviewed-by: Liam R. Howlett <Liam.Howlett@...cle.com>

> ---
>  fs/hugetlbfs/inode.c           | 14 +++++++-------
>  include/linux/hugetlb.h        |  6 +++---
>  include/linux/hugetlb_inline.h | 10 ++++++++++
>  ipc/shm.c                      | 12 +++++++-----
>  mm/hugetlb.c                   | 22 +++++++++++-----------
>  mm/memfd.c                     |  4 ++--
>  mm/mmap.c                      |  2 +-
>  7 files changed, 41 insertions(+), 29 deletions(-)
> 
> diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c
> index 3b4c152c5c73..95a5b23b4808 100644
> --- a/fs/hugetlbfs/inode.c
> +++ b/fs/hugetlbfs/inode.c
> @@ -109,7 +109,7 @@ static int hugetlbfs_file_mmap_prepare(struct vm_area_desc *desc)
>  	loff_t len, vma_len;
>  	int ret;
>  	struct hstate *h = hstate_file(file);
> -	vm_flags_t vm_flags;
> +	vma_flags_t vma_flags;
>  
>  	/*
>  	 * vma address alignment (but not the pgoff alignment) has
> @@ -119,7 +119,7 @@ static int hugetlbfs_file_mmap_prepare(struct vm_area_desc *desc)
>  	 * way when do_mmap unwinds (may be important on powerpc
>  	 * and ia64).
>  	 */
> -	desc->vm_flags |= VM_HUGETLB | VM_DONTEXPAND;
> +	vma_desc_set_flags(desc, VMA_HUGETLB_BIT, VMA_DONTEXPAND_BIT);
>  	desc->vm_ops = &hugetlb_vm_ops;
>  
>  	/*
> @@ -148,23 +148,23 @@ static int hugetlbfs_file_mmap_prepare(struct vm_area_desc *desc)
>  
>  	ret = -ENOMEM;
>  
> -	vm_flags = desc->vm_flags;
> +	vma_flags = desc->vma_flags;
>  	/*
>  	 * for SHM_HUGETLB, the pages are reserved in the shmget() call so skip
>  	 * reserving here. Note: only for SHM hugetlbfs file, the inode
>  	 * flag S_PRIVATE is set.
>  	 */
>  	if (inode->i_flags & S_PRIVATE)
> -		vm_flags |= VM_NORESERVE;
> +		vma_flags_set(&vma_flags, VMA_NORESERVE_BIT);
>  
>  	if (hugetlb_reserve_pages(inode,
>  			desc->pgoff >> huge_page_order(h),
>  			len >> huge_page_shift(h), desc,
> -			vm_flags) < 0)
> +			vma_flags) < 0)
>  		goto out;
>  
>  	ret = 0;
> -	if ((desc->vm_flags & VM_WRITE) && inode->i_size < len)
> +	if (vma_desc_test_flags(desc, VMA_WRITE_BIT) && inode->i_size < len)
>  		i_size_write(inode, len);
>  out:
>  	inode_unlock(inode);
> @@ -1527,7 +1527,7 @@ static int get_hstate_idx(int page_size_log)
>   * otherwise hugetlb_reserve_pages reserves one less hugepages than intended.
>   */
>  struct file *hugetlb_file_setup(const char *name, size_t size,
> -				vm_flags_t acctflag, int creat_flags,
> +				vma_flags_t acctflag, int creat_flags,
>  				int page_size_log)
>  {
>  	struct inode *inode;
> diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
> index 94a03591990c..4e72bf66077e 100644
> --- a/include/linux/hugetlb.h
> +++ b/include/linux/hugetlb.h
> @@ -150,7 +150,7 @@ int hugetlb_mfill_atomic_pte(pte_t *dst_pte,
>  			     struct folio **foliop);
>  #endif /* CONFIG_USERFAULTFD */
>  long hugetlb_reserve_pages(struct inode *inode, long from, long to,
> -			   struct vm_area_desc *desc, vm_flags_t vm_flags);
> +			   struct vm_area_desc *desc, vma_flags_t vma_flags);
>  long hugetlb_unreserve_pages(struct inode *inode, long start, long end,
>  						long freed);
>  bool folio_isolate_hugetlb(struct folio *folio, struct list_head *list);
> @@ -529,7 +529,7 @@ static inline struct hugetlbfs_inode_info *HUGETLBFS_I(struct inode *inode)
>  }
>  
>  extern const struct vm_operations_struct hugetlb_vm_ops;
> -struct file *hugetlb_file_setup(const char *name, size_t size, vm_flags_t acct,
> +struct file *hugetlb_file_setup(const char *name, size_t size, vma_flags_t acct,
>  				int creat_flags, int page_size_log);
>  
>  static inline bool is_file_hugepages(const struct file *file)
> @@ -545,7 +545,7 @@ static inline struct hstate *hstate_inode(struct inode *i)
>  
>  #define is_file_hugepages(file)			false
>  static inline struct file *
> -hugetlb_file_setup(const char *name, size_t size, vm_flags_t acctflag,
> +hugetlb_file_setup(const char *name, size_t size, vma_flags_t acctflag,
>  		int creat_flags, int page_size_log)
>  {
>  	return ERR_PTR(-ENOSYS);
> diff --git a/include/linux/hugetlb_inline.h b/include/linux/hugetlb_inline.h
> index a27aa0162918..593f5d4e108b 100644
> --- a/include/linux/hugetlb_inline.h
> +++ b/include/linux/hugetlb_inline.h
> @@ -11,6 +11,11 @@ static inline bool is_vm_hugetlb_flags(vm_flags_t vm_flags)
>  	return !!(vm_flags & VM_HUGETLB);
>  }
>  
> +static inline bool is_vma_hugetlb_flags(const vma_flags_t *flags)
> +{
> +	return vma_flags_test(flags, VMA_HUGETLB_BIT);
> +}
> +
>  #else
>  
>  static inline bool is_vm_hugetlb_flags(vm_flags_t vm_flags)
> @@ -18,6 +23,11 @@ static inline bool is_vm_hugetlb_flags(vm_flags_t vm_flags)
>  	return false;
>  }
>  
> +static inline bool is_vma_hugetlb_flags(const vma_flags_t *flags)
> +{
> +	return false;
> +}
> +
>  #endif
>  
>  static inline bool is_vm_hugetlb_page(struct vm_area_struct *vma)
> diff --git a/ipc/shm.c b/ipc/shm.c
> index 3db36773dd10..2c7379c4c647 100644
> --- a/ipc/shm.c
> +++ b/ipc/shm.c
> @@ -707,9 +707,9 @@ static int newseg(struct ipc_namespace *ns, struct ipc_params *params)
>  	int error;
>  	struct shmid_kernel *shp;
>  	size_t numpages = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
> +	const bool has_no_reserve = shmflg & SHM_NORESERVE;
>  	struct file *file;
>  	char name[13];
> -	vm_flags_t acctflag = 0;
>  
>  	if (size < SHMMIN || size > ns->shm_ctlmax)
>  		return -EINVAL;
> @@ -738,6 +738,7 @@ static int newseg(struct ipc_namespace *ns, struct ipc_params *params)
>  
>  	sprintf(name, "SYSV%08x", key);
>  	if (shmflg & SHM_HUGETLB) {
> +		vma_flags_t acctflag = EMPTY_VMA_FLAGS;
>  		struct hstate *hs;
>  		size_t hugesize;
>  
> @@ -749,17 +750,18 @@ static int newseg(struct ipc_namespace *ns, struct ipc_params *params)
>  		hugesize = ALIGN(size, huge_page_size(hs));
>  
>  		/* hugetlb_file_setup applies strict accounting */
> -		if (shmflg & SHM_NORESERVE)
> -			acctflag = VM_NORESERVE;
> +		if (has_no_reserve)
> +			vma_flags_set(&acctflag, VMA_NORESERVE_BIT);
>  		file = hugetlb_file_setup(name, hugesize, acctflag,
>  				HUGETLB_SHMFS_INODE, (shmflg >> SHM_HUGE_SHIFT) & SHM_HUGE_MASK);
>  	} else {
> +		vm_flags_t acctflag = 0;
> +
>  		/*
>  		 * Do not allow no accounting for OVERCOMMIT_NEVER, even
>  		 * if it's asked for.
>  		 */
> -		if  ((shmflg & SHM_NORESERVE) &&
> -				sysctl_overcommit_memory != OVERCOMMIT_NEVER)
> +		if  (has_no_reserve && sysctl_overcommit_memory != OVERCOMMIT_NEVER)
>  			acctflag = VM_NORESERVE;
>  		file = shmem_kernel_file_setup(name, size, acctflag);
>  	}
> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> index 4f4494251f5c..e6955061d751 100644
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -1193,16 +1193,16 @@ static void set_vma_resv_flags(struct vm_area_struct *vma, unsigned long flags)
>  
>  static void set_vma_desc_resv_map(struct vm_area_desc *desc, struct resv_map *map)
>  {
> -	VM_WARN_ON_ONCE(!is_vm_hugetlb_flags(desc->vm_flags));
> -	VM_WARN_ON_ONCE(desc->vm_flags & VM_MAYSHARE);
> +	VM_WARN_ON_ONCE(!is_vma_hugetlb_flags(&desc->vma_flags));
> +	VM_WARN_ON_ONCE(vma_desc_test_flags(desc, VMA_MAYSHARE_BIT));
>  
>  	desc->private_data = map;
>  }
>  
>  static void set_vma_desc_resv_flags(struct vm_area_desc *desc, unsigned long flags)
>  {
> -	VM_WARN_ON_ONCE(!is_vm_hugetlb_flags(desc->vm_flags));
> -	VM_WARN_ON_ONCE(desc->vm_flags & VM_MAYSHARE);
> +	VM_WARN_ON_ONCE(!is_vma_hugetlb_flags(&desc->vma_flags));
> +	VM_WARN_ON_ONCE(vma_desc_test_flags(desc, VMA_MAYSHARE_BIT));
>  
>  	desc->private_data = (void *)((unsigned long)desc->private_data | flags);
>  }
> @@ -1216,7 +1216,7 @@ static int is_vma_resv_set(struct vm_area_struct *vma, unsigned long flag)
>  
>  static bool is_vma_desc_resv_set(struct vm_area_desc *desc, unsigned long flag)
>  {
> -	VM_WARN_ON_ONCE(!is_vm_hugetlb_flags(desc->vm_flags));
> +	VM_WARN_ON_ONCE(!is_vma_hugetlb_flags(&desc->vma_flags));
>  
>  	return ((unsigned long)desc->private_data) & flag;
>  }
> @@ -6564,7 +6564,7 @@ long hugetlb_change_protection(struct vm_area_struct *vma,
>  long hugetlb_reserve_pages(struct inode *inode,
>  		long from, long to,
>  		struct vm_area_desc *desc,
> -		vm_flags_t vm_flags)
> +		vma_flags_t vma_flags)
>  {
>  	long chg = -1, add = -1, spool_resv, gbl_resv;
>  	struct hstate *h = hstate_inode(inode);
> @@ -6585,7 +6585,7 @@ long hugetlb_reserve_pages(struct inode *inode,
>  	 * attempt will be made for VM_NORESERVE to allocate a page
>  	 * without using reserves
>  	 */
> -	if (vm_flags & VM_NORESERVE)
> +	if (vma_flags_test(&vma_flags, VMA_NORESERVE_BIT))
>  		return 0;
>  
>  	/*
> @@ -6594,7 +6594,7 @@ long hugetlb_reserve_pages(struct inode *inode,
>  	 * to reserve the full area even if read-only as mprotect() may be
>  	 * called to make the mapping read-write. Assume !desc is a shm mapping
>  	 */
> -	if (!desc || desc->vm_flags & VM_MAYSHARE) {
> +	if (!desc || vma_desc_test_flags(desc, VMA_MAYSHARE_BIT)) {
>  		/*
>  		 * resv_map can not be NULL as hugetlb_reserve_pages is only
>  		 * called for inodes for which resv_maps were created (see
> @@ -6628,7 +6628,7 @@ long hugetlb_reserve_pages(struct inode *inode,
>  	if (err < 0)
>  		goto out_err;
>  
> -	if (desc && !(desc->vm_flags & VM_MAYSHARE) && h_cg) {
> +	if (desc && !vma_desc_test_flags(desc, VMA_MAYSHARE_BIT) && h_cg) {
>  		/* For private mappings, the hugetlb_cgroup uncharge info hangs
>  		 * of the resv_map.
>  		 */
> @@ -6665,7 +6665,7 @@ long hugetlb_reserve_pages(struct inode *inode,
>  	 * consumed reservations are stored in the map. Hence, nothing
>  	 * else has to be done for private mappings here
>  	 */
> -	if (!desc || desc->vm_flags & VM_MAYSHARE) {
> +	if (!desc || vma_desc_test_flags(desc, VMA_MAYSHARE_BIT)) {
>  		add = region_add(resv_map, from, to, regions_needed, h, h_cg);
>  
>  		if (unlikely(add < 0)) {
> @@ -6729,7 +6729,7 @@ long hugetlb_reserve_pages(struct inode *inode,
>  	hugetlb_cgroup_uncharge_cgroup_rsvd(hstate_index(h),
>  					    chg * pages_per_huge_page(h), h_cg);
>  out_err:
> -	if (!desc || desc->vm_flags & VM_MAYSHARE)
> +	if (!desc || vma_desc_test_flags(desc, VMA_MAYSHARE_BIT))
>  		/* Only call region_abort if the region_chg succeeded but the
>  		 * region_add failed or didn't run.
>  		 */
> diff --git a/mm/memfd.c b/mm/memfd.c
> index ab5312aff14b..5f95f639550c 100644
> --- a/mm/memfd.c
> +++ b/mm/memfd.c
> @@ -87,7 +87,7 @@ struct folio *memfd_alloc_folio(struct file *memfd, pgoff_t idx)
>  		gfp_mask &= ~(__GFP_HIGHMEM | __GFP_MOVABLE);
>  		idx >>= huge_page_order(h);
>  
> -		nr_resv = hugetlb_reserve_pages(inode, idx, idx + 1, NULL, 0);
> +		nr_resv = hugetlb_reserve_pages(inode, idx, idx + 1, NULL, EMPTY_VMA_FLAGS);
>  		if (nr_resv < 0)
>  			return ERR_PTR(nr_resv);
>  
> @@ -464,7 +464,7 @@ static struct file *alloc_file(const char *name, unsigned int flags)
>  	int err = 0;
>  
>  	if (flags & MFD_HUGETLB) {
> -		file = hugetlb_file_setup(name, 0, VM_NORESERVE,
> +		file = hugetlb_file_setup(name, 0, mk_vma_flags(VMA_NORESERVE_BIT),
>  					HUGETLB_ANONHUGE_INODE,
>  					(flags >> MFD_HUGE_SHIFT) &
>  					MFD_HUGE_MASK);
> diff --git a/mm/mmap.c b/mm/mmap.c
> index 8771b276d63d..038ff5f09df0 100644
> --- a/mm/mmap.c
> +++ b/mm/mmap.c
> @@ -594,7 +594,7 @@ unsigned long ksys_mmap_pgoff(unsigned long addr, unsigned long len,
>  		 * taken when vm_ops->mmap() is called
>  		 */
>  		file = hugetlb_file_setup(HUGETLB_ANON_FILE, len,
> -				VM_NORESERVE,
> +				mk_vma_flags(VMA_NORESERVE_BIT),
>  				HUGETLB_ANONHUGE_INODE,
>  				(flags >> MAP_HUGE_SHIFT) & MAP_HUGE_MASK);
>  		if (IS_ERR(file))
> -- 
> 2.52.0
> 

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