mm: anonymous shared memory naming

Message ID	20221105025342.3130038-1-pasha.tatashin@soleen.com (mailing list archive)
State	New
Headers	show Return-Path: <owner-linux-mm@kvack.org> From: Pasha Tatashin <pasha.tatashin@soleen.com> To: corbet@lwn.net, akpm@linux-foundation.org, hughd@google.com, hannes@cmpxchg.org, david@redhat.com, vincent.whitchurch@axis.com, seanjc@google.com, rppt@kernel.org, shy828301@gmail.com, pasha.tatashin@soleen.com, paul.gortmaker@windriver.com, peterx@redhat.com, vbabka@suse.cz, Liam.Howlett@Oracle.com, ccross@google.com, willy@infradead.org, arnd@arndb.de, cgel.zte@gmail.com, yuzhao@google.com, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-doc@vger.kernel.org, linux-mm@kvack.org Subject: [PATCH] mm: anonymous shared memory naming Date: Sat, 5 Nov 2022 02:53:42 +0000 Message-Id: <20221105025342.3130038-1-pasha.tatashin@soleen.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: owner-linux-mm@kvack.org Precedence: bulk
Series	mm: anonymous shared memory naming \| expand mm: anonymous shared memory naming

diff --git a/Documentation/filesystems/proc.rst b/Documentation/filesystems/proc.rst index 898c99eae8e4..8f1e68460da5 100644 --- a/Documentation/filesystems/proc.rst +++ b/Documentation/filesystems/proc.rst @@ -431,8 +431,10 @@ is not associated with a file: [stack] the stack of the main process [vdso] the "virtual dynamic shared object", the kernel system call handler - [anon:<name>] an anonymous mapping that has been + [anon:<name>] a private anonymous mapping that has been named by userspace + path [anon_shmem:<name>] an anonymous shared memory mapping that has + been named by userspace ============= ==================================== or if empty, the mapping is anonymous. diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index 8a74cdcc9af0..d6ae75ed81ca 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -277,6 +277,7 @@ show_map_vma(struct seq_file *m, struct vm_area_struct *vma) struct mm_struct *mm = vma->vm_mm; struct file *file = vma->vm_file; vm_flags_t flags = vma->vm_flags; + struct anon_vma_name *anon_name; unsigned long ino = 0; unsigned long long pgoff = 0; unsigned long start, end; @@ -293,6 +294,7 @@ show_map_vma(struct seq_file *m, struct vm_area_struct *vma) start = vma->vm_start; end = vma->vm_end; show_vma_header_prefix(m, start, end, flags, pgoff, dev, ino); + anon_name = anon_vma_name(vma); /* * Print the dentry name for named mappings, and a @@ -301,6 +303,8 @@ show_map_vma(struct seq_file *m, struct vm_area_struct *vma) if (file) { seq_pad(m, ' '); seq_file_path(m, file, "\n"); + if (anon_name) + seq_printf(m, " [anon_shmem:%s]", anon_name->name); goto done; } @@ -312,8 +316,6 @@ show_map_vma(struct seq_file *m, struct vm_area_struct *vma) name = arch_vma_name(vma); if (!name) { - struct anon_vma_name *anon_name; - if (!mm) { name = "[vdso]"; goto done; @@ -330,7 +332,6 @@ show_map_vma(struct seq_file *m, struct vm_area_struct *vma) goto done; } - anon_name = anon_vma_name(vma); if (anon_name) { seq_pad(m, ' '); seq_printf(m, "[anon:%s]", anon_name->name); diff --git a/include/linux/mm.h b/include/linux/mm.h index 8bbcccbc5565..06b6fb3277ab 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -699,8 +699,10 @@ static inline unsigned long vma_iter_addr(struct vma_iterator *vmi) * paths in userfault. */ bool vma_is_shmem(struct vm_area_struct *vma); +bool vma_is_anon_shmem(struct vm_area_struct *vma); #else static inline bool vma_is_shmem(struct vm_area_struct *vma) { return false; } +static inline bool vma_is_anon_shmem(struct vm_area_struct *vma) { return false; } #endif int vma_is_stack_for_current(struct vm_area_struct *vma); diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h index 500e536796ca..08d8b973fb60 100644 --- a/include/linux/mm_types.h +++ b/include/linux/mm_types.h @@ -461,21 +461,11 @@ struct vm_area_struct { * For areas with an address space and backing store, * linkage into the address_space->i_mmap interval tree. * - * For private anonymous mappings, a pointer to a null terminated string - * containing the name given to the vma, or NULL if unnamed. */ - - union { - struct { - struct rb_node rb; - unsigned long rb_subtree_last; - } shared; - /* - * Serialized by mmap_sem. Never use directly because it is - * valid only when vm_file is NULL. Use anon_vma_name instead. - */ - struct anon_vma_name *anon_name; - }; + struct { + struct rb_node rb; + unsigned long rb_subtree_last; + } shared; /* * A file's MAP_PRIVATE vma can be in both i_mmap tree and anon_vma @@ -485,6 +475,7 @@ struct vm_area_struct { */ 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. */ @@ -496,6 +487,14 @@ struct vm_area_struct { struct file * vm_file; /* File we map to (can be NULL). */ void * vm_private_data; /* was vm_pte (shared mem) */ +#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_sem. Use anon_vma_name to access. + */ + struct anon_vma_name *anon_name; +#endif #ifdef CONFIG_SWAP atomic_long_t swap_readahead_info; #endif diff --git a/mm/madvise.c b/mm/madvise.c index c7105ec6d08c..255d5b485432 100644 --- a/mm/madvise.c +++ b/mm/madvise.c @@ -95,9 +95,6 @@ struct anon_vma_name *anon_vma_name(struct vm_area_struct *vma) { mmap_assert_locked(vma->vm_mm); - if (vma->vm_file) - return NULL; - return vma->anon_name; } @@ -183,7 +180,7 @@ static int madvise_update_vma(struct vm_area_struct *vma, * vm_flags is protected by the mmap_lock held in write mode. */ vma->vm_flags = new_flags; - if (!vma->vm_file) { + if (!vma->vm_file || vma_is_anon_shmem(vma)) { error = replace_anon_vma_name(vma, anon_name); if (error) return error; @@ -1273,7 +1270,7 @@ static int madvise_vma_anon_name(struct vm_area_struct *vma, int error; /* Only anonymous mappings can be named */ - if (vma->vm_file) + if (vma->vm_file && !vma_is_anon_shmem(vma)) return -EBADF; error = madvise_update_vma(vma, prev, start, end, vma->vm_flags, diff --git a/mm/shmem.c b/mm/shmem.c index c1d8b8a1aa3b..638bcb3d26bd 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -237,11 +237,17 @@ static const struct inode_operations shmem_inode_operations; static const struct inode_operations shmem_dir_inode_operations; static const struct inode_operations shmem_special_inode_operations; static const struct vm_operations_struct shmem_vm_ops; +static const struct vm_operations_struct shmem_anon_vm_ops; static struct file_system_type shmem_fs_type; +bool vma_is_anon_shmem(struct vm_area_struct *vma) +{ + return vma->vm_ops == &shmem_anon_vm_ops; +} + bool vma_is_shmem(struct vm_area_struct *vma) { - return vma->vm_ops == &shmem_vm_ops; + return vma_is_anon_shmem(vma) || vma->vm_ops == &shmem_vm_ops; } static LIST_HEAD(shmem_swaplist); @@ -3995,6 +4001,8 @@ static const struct vm_operations_struct shmem_vm_ops = { #endif }; +static const struct vm_operations_struct shmem_anon_vm_ops = shmem_vm_ops; + int shmem_init_fs_context(struct fs_context *fc) { struct shmem_options *ctx; @@ -4170,6 +4178,7 @@ void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend) EXPORT_SYMBOL_GPL(shmem_truncate_range); #define shmem_vm_ops generic_file_vm_ops +#define shmem_anon_vm_ops generic_file_vm_ops #define shmem_file_operations ramfs_file_operations #define shmem_get_inode(sb, dir, mode, dev, flags) ramfs_get_inode(sb, dir, mode, dev) #define shmem_acct_size(flags, size) 0 @@ -4275,7 +4284,7 @@ int shmem_zero_setup(struct vm_area_struct *vma) if (vma->vm_file) fput(vma->vm_file); vma->vm_file = file; - vma->vm_ops = &shmem_vm_ops; + vma->vm_ops = &shmem_anon_vm_ops; return 0; }

mm: anonymous shared memory naming

Commit Message

Comments

Patch