The patch titled
Subject: mm: anonymous shared memory naming
has been added to the -mm mm-unstable branch. Its filename is
mm-anonymous-shared-memory-naming.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-anonymous-shared-memory-naming.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next via the mm-everything
branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there every 2-3 working days
------------------------------------------------------
From: Pasha Tatashin <pasha.tatashin@xxxxxxxxxx>
Subject: mm: anonymous shared memory naming
Date: Mon, 7 Nov 2022 18:47:15 +0000
Since commit 9a10064f5625 ("mm: add a field to store names for private
anonymous memory"), name for private anonymous memory, but not shared
anonymous, can be set. However, naming shared anonymous memory just as
useful for tracking purposes.
Extend the functionality to be able to set names for shared anon.
Sample output:
/* Create shared anonymous segmenet */
anon_shmem = mmap(NULL, SIZE, PROT_READ | PROT_WRITE,
MAP_SHARED | MAP_ANONYMOUS, -1, 0);
/* Name the segment: "MY-NAME" */
rv = prctl(PR_SET_VMA, PR_SET_VMA_ANON_NAME,
anon_shmem, SIZE, "MY-NAME");
cat /proc/<pid>/maps (and smaps):
7fc8e2b4c000-7fc8f2b4c000 rw-s 00000000 00:01 1024 [anon_shmem:MY-NAME]
Link: https://lkml.kernel.org/r/20221107184715.3950621-1-pasha.tatashin@xxxxxxxxxx
Signed-off-by: Pasha Tatashin <pasha.tatashin@xxxxxxxxxx>
Cc: Arnd Bergmann <arnd@xxxxxxxx>
Cc: Bagas Sanjaya <bagasdotme@xxxxxxxxx>
Cc: Colin Cross <ccross@xxxxxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Jonathan Corbet <corbet@xxxxxxx>
Cc: "Kirill A . Shutemov" <kirill@xxxxxxxxxxxxx>
Cc: Liam Howlett <liam.howlett@xxxxxxxxxx>
Cc: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Cc: Mike Rapoport <rppt@xxxxxxxxxx>
Cc: Paul Gortmaker <paul.gortmaker@xxxxxxxxxxxxx>
Cc: Peter Xu <peterx@xxxxxxxxxx>
Cc: Sean Christopherson <seanjc@xxxxxxxxxx>
Cc: Vincent Whitchurch <vincent.whitchurch@xxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Cc: xu xin <cgel.zte@xxxxxxxxx>
Cc: Yang Shi <shy828301@xxxxxxxxx>
Cc: Yu Zhao <yuzhao@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
Documentation/filesystems/proc.rst | 8 +++++---
fs/proc/task_mmu.c | 14 ++++++++++----
include/linux/mm.h | 2 ++
include/linux/mm_types.h | 27 +++++++++++++--------------
mm/madvise.c | 7 ++-----
mm/shmem.c | 20 ++++++++++++++++++--
6 files changed, 50 insertions(+), 28 deletions(-)
--- a/Documentation/filesystems/proc.rst~mm-anonymous-shared-memory-naming
+++ a/Documentation/filesystems/proc.rst
@@ -426,14 +426,16 @@ with the memory region, as the case woul
The "pathname" shows the name associated file for this mapping. If the mapping
is not associated with a file:
- ============= ====================================
+ =================== ===========================================
[heap] the heap of the program
[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
- ============= ====================================
+ [anon_shmem:<name>] an anonymous shared memory mapping that has
+ been named by userspace
+ =================== ===========================================
or if empty, the mapping is anonymous.
--- a/fs/proc/task_mmu.c~mm-anonymous-shared-memory-naming
+++ a/fs/proc/task_mmu.c
@@ -277,6 +277,7 @@ show_map_vma(struct seq_file *m, struct
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
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
@@ -300,7 +302,14 @@ show_map_vma(struct seq_file *m, struct
*/
if (file) {
seq_pad(m, ' ');
- seq_file_path(m, file, "\n");
+ /*
+ * If user named this anon shared memory via
+ * prctl(PR_SET_VMA ..., use the provided name.
+ */
+ if (anon_name)
+ seq_printf(m, "[anon_shmem:%s]", anon_name->name);
+ else
+ seq_file_path(m, file, "\n");
goto done;
}
@@ -312,8 +321,6 @@ show_map_vma(struct seq_file *m, struct
name = arch_vma_name(vma);
if (!name) {
- struct anon_vma_name *anon_name;
-
if (!mm) {
name = "[vdso]";
goto done;
@@ -330,7 +337,6 @@ show_map_vma(struct seq_file *m, struct
goto done;
}
- anon_name = anon_vma_name(vma);
if (anon_name) {
seq_pad(m, ' ');
seq_printf(m, "[anon:%s]", anon_name->name);
--- a/include/linux/mm.h~mm-anonymous-shared-memory-naming
+++ a/include/linux/mm.h
@@ -700,8 +700,10 @@ static inline unsigned long vma_iter_add
* 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);
--- a/include/linux/mm_types.h~mm-anonymous-shared-memory-naming
+++ a/include/linux/mm_types.h
@@ -515,21 +515,11 @@ 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
@@ -539,6 +529,7 @@ 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. */
@@ -550,6 +541,14 @@ 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
--- a/mm/madvise.c~mm-anonymous-shared-memory-naming
+++ a/mm/madvise.c
@@ -95,9 +95,6 @@ struct anon_vma_name *anon_vma_name(stru
{
mmap_assert_locked(vma->vm_mm);
- if (vma->vm_file)
- return NULL;
-
return vma->anon_name;
}
@@ -183,7 +180,7 @@ success:
* 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
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,
--- a/mm/shmem.c~mm-anonymous-shared-memory-naming
+++ a/mm/shmem.c
@@ -237,11 +237,17 @@ static const struct inode_operations shm
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);
@@ -3988,6 +3994,15 @@ static const struct vm_operations_struct
#endif
};
+static const struct vm_operations_struct shmem_anon_vm_ops = {
+ .fault = shmem_fault,
+ .map_pages = filemap_map_pages,
+#ifdef CONFIG_NUMA
+ .set_policy = shmem_set_policy,
+ .get_policy = shmem_get_policy,
+#endif
+};
+
int shmem_init_fs_context(struct fs_context *fc)
{
struct shmem_options *ctx;
@@ -4163,6 +4178,7 @@ void shmem_truncate_range(struct inode *
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
@@ -4268,7 +4284,7 @@ int shmem_zero_setup(struct vm_area_stru
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;
}
_
Patches currently in -mm which might be from pasha.tatashin@xxxxxxxxxx are
mm-anonymous-shared-memory-naming.patch
