Commit 5c26f6ac authored by Suren Baghdasaryan's avatar Suren Baghdasaryan Committed by Linus Torvalds
Browse files

mm: refactor vm_area_struct::anon_vma_name usage code 

Avoid mixing strings and their anon_vma_name referenced pointers by
using struct anon_vma_name whenever possible.  This simplifies the code
and allows easier sharing of anon_vma_name structures when they
represent the same name.

[surenb@google.com: fix comment]

Link: https://lkml.kernel.org/r/20220223153613.835563-1-surenb@google.com
Link: https://lkml.kernel.org/r/20220224231834.1481408-1-surenb@google.com


Signed-off-by: default avatarSuren Baghdasaryan <surenb@google.com>
Suggested-by: default avatarMatthew Wilcox <willy@infradead.org>
Suggested-by: default avatarMichal Hocko <mhocko@suse.com>
Acked-by: default avatarMichal Hocko <mhocko@suse.com>
Cc: Colin Cross <ccross@google.com>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Alexey Gladkov <legion@kernel.org>
Cc: Sasha Levin <sashal@kernel.org>
Cc: Chris Hyser <chris.hyser@oracle.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Peter Collingbourne <pcc@google.com>
Cc: Xiaofeng Cao <caoxiaofeng@yulong.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Cyrill Gorcunov <gorcunov@gmail.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent ff712a62

fs/proc/task_mmu.c

+3 −3
Original line number Diff line number Diff line
@@ -309,7 +309,7 @@ show_map_vma(struct seq_file *m, struct vm_area_struct *vma) 


	name = arch_vma_name(vma);

	if (!name) {

		const char *anon_name;

		struct anon_vma_name *anon_name;



		if (!mm) {

			name = "[vdso]";
@@ -327,10 +327,10 @@ show_map_vma(struct seq_file *m, struct vm_area_struct *vma) 
			goto done;

		}



		anon_name = vma_anon_name(vma);

		anon_name = anon_vma_name(vma);

		if (anon_name) {

			seq_pad(m, ' ');

			seq_printf(m, "[anon:%s]", anon_name);

			seq_printf(m, "[anon:%s]", anon_name->name);

		}

	}

fs/userfaultfd.c

+3 −3
Original line number Diff line number Diff line
@@ -878,7 +878,7 @@ static int userfaultfd_release(struct inode *inode, struct file *file) 
				 new_flags, vma->anon_vma,

				 vma->vm_file, vma->vm_pgoff,

				 vma_policy(vma),

				 NULL_VM_UFFD_CTX, vma_anon_name(vma));

				 NULL_VM_UFFD_CTX, anon_vma_name(vma));

		if (prev)

			vma = prev;

		else
@@ -1438,7 +1438,7 @@ static int userfaultfd_register(struct userfaultfd_ctx *ctx, 
				 vma->anon_vma, vma->vm_file, vma->vm_pgoff,

				 vma_policy(vma),

				 ((struct vm_userfaultfd_ctx){ ctx }),

				 vma_anon_name(vma));

				 anon_vma_name(vma));

		if (prev) {

			vma = prev;

			goto next;
@@ -1615,7 +1615,7 @@ static int userfaultfd_unregister(struct userfaultfd_ctx *ctx, 
		prev = vma_merge(mm, prev, start, vma_end, new_flags,

				 vma->anon_vma, vma->vm_file, vma->vm_pgoff,

				 vma_policy(vma),

				 NULL_VM_UFFD_CTX, vma_anon_name(vma));

				 NULL_VM_UFFD_CTX, anon_vma_name(vma));

		if (prev) {

			vma = prev;

			goto next;

include/linux/mm.h

+4 −3
Original line number Diff line number Diff line
@@ -2626,7 +2626,7 @@ static inline int vma_adjust(struct vm_area_struct *vma, unsigned long start, 
extern struct vm_area_struct *vma_merge(struct mm_struct *,

	struct vm_area_struct *prev, unsigned long addr, unsigned long end,

	unsigned long vm_flags, struct anon_vma *, struct file *, pgoff_t,

	struct mempolicy *, struct vm_userfaultfd_ctx, const char *);

	struct mempolicy *, struct vm_userfaultfd_ctx, struct anon_vma_name *);

extern struct anon_vma *find_mergeable_anon_vma(struct vm_area_struct *);

extern int __split_vma(struct mm_struct *, struct vm_area_struct *,

	unsigned long addr, int new_below);
@@ -3372,11 +3372,12 @@ static inline int seal_check_future_write(int seals, struct vm_area_struct *vma) 


#ifdef CONFIG_ANON_VMA_NAME

int madvise_set_anon_name(struct mm_struct *mm, unsigned long start,

			  unsigned long len_in, const char *name);

			  unsigned long len_in,

			  struct anon_vma_name *anon_name);

#else

static inline int

madvise_set_anon_name(struct mm_struct *mm, unsigned long start,

		      unsigned long len_in, const char *name) {

		      unsigned long len_in, struct anon_vma_name *anon_name) {

	return 0;

}

#endif

include/linux/mm_inline.h

+59 −28
Original line number Diff line number Diff line
@@ -140,50 +140,81 @@ static __always_inline void del_page_from_lru_list(struct page *page, 


#ifdef CONFIG_ANON_VMA_NAME

/*

 * mmap_lock should be read-locked when calling vma_anon_name() and while using

 * the returned pointer.

 * mmap_lock should be read-locked when calling anon_vma_name(). Caller should

 * either keep holding the lock while using the returned pointer or it should

 * raise anon_vma_name refcount before releasing the lock.

 */

extern const char *vma_anon_name(struct vm_area_struct *vma);

extern struct anon_vma_name *anon_vma_name(struct vm_area_struct *vma);

extern struct anon_vma_name *anon_vma_name_alloc(const char *name);

extern void anon_vma_name_free(struct kref *kref);



/*

 * mmap_lock should be read-locked for orig_vma->vm_mm.

 * mmap_lock should be write-locked for new_vma->vm_mm or new_vma should be

 * isolated.

 */

extern void dup_vma_anon_name(struct vm_area_struct *orig_vma,

			      struct vm_area_struct *new_vma);

/* mmap_lock should be read-locked */

static inline void anon_vma_name_get(struct anon_vma_name *anon_name)

{

	if (anon_name)

		kref_get(&anon_name->kref);

}



static inline void anon_vma_name_put(struct anon_vma_name *anon_name)

{

	if (anon_name)

		kref_put(&anon_name->kref, anon_vma_name_free);

}



static inline void dup_anon_vma_name(struct vm_area_struct *orig_vma,

				     struct vm_area_struct *new_vma)

{

	struct anon_vma_name *anon_name = anon_vma_name(orig_vma);



	if (anon_name) {

		anon_vma_name_get(anon_name);

		new_vma->anon_name = anon_name;

	}

}



static inline void free_anon_vma_name(struct vm_area_struct *vma)

{

	/*

 * mmap_lock should be write-locked or vma should have been isolated under

 * write-locked mmap_lock protection.

	 * Not using anon_vma_name because it generates a warning if mmap_lock

	 * is not held, which might be the case here.

	 */

extern void free_vma_anon_name(struct vm_area_struct *vma);

	if (!vma->vm_file)

		anon_vma_name_put(vma->anon_name);

}



/* mmap_lock should be read-locked */

static inline bool is_same_vma_anon_name(struct vm_area_struct *vma,

					 const char *name)

static inline bool anon_vma_name_eq(struct anon_vma_name *anon_name1,

				    struct anon_vma_name *anon_name2)

{

	const char *vma_name = vma_anon_name(vma);



	/* either both NULL, or pointers to same string */

	if (vma_name == name)

	if (anon_name1 == anon_name2)

		return true;



	return name && vma_name && !strcmp(name, vma_name);

	return anon_name1 && anon_name2 &&

		!strcmp(anon_name1->name, anon_name2->name);

}



#else /* CONFIG_ANON_VMA_NAME */

static inline const char *vma_anon_name(struct vm_area_struct *vma)

static inline struct anon_vma_name *anon_vma_name(struct vm_area_struct *vma)

{

	return NULL;

}



static inline struct anon_vma_name *anon_vma_name_alloc(const char *name)

{

	return NULL;

}

static inline void dup_vma_anon_name(struct vm_area_struct *orig_vma,



static inline void anon_vma_name_get(struct anon_vma_name *anon_name) {}

static inline void anon_vma_name_put(struct anon_vma_name *anon_name) {}

static inline void dup_anon_vma_name(struct vm_area_struct *orig_vma,

				     struct vm_area_struct *new_vma) {}

static inline void free_vma_anon_name(struct vm_area_struct *vma) {}

static inline bool is_same_vma_anon_name(struct vm_area_struct *vma,

					 const char *name)

static inline void free_anon_vma_name(struct vm_area_struct *vma) {}



static inline bool anon_vma_name_eq(struct anon_vma_name *anon_name1,

				    struct anon_vma_name *anon_name2)

{

	return true;

}



#endif  /* CONFIG_ANON_VMA_NAME */



static inline void init_tlb_flush_pending(struct mm_struct *mm)

include/linux/mm_types.h

+4 −1
Original line number Diff line number Diff line
@@ -416,7 +416,10 @@ struct vm_area_struct { 
			struct rb_node rb;

			unsigned long rb_subtree_last;

		} shared;

		/* Serialized by mmap_sem. */

		/*

		 * 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;

	};