3 * Copyright (C) 1992, 1993 Krishna Balasubramanian
4 * Many improvements/fixes by Bruno Haible.
5 * Replaced `struct shm_desc' by `struct vm_area_struct', July 1994.
6 * Fixed the shm swap deallocation (shm_unuse()), August 1998 Andrea Arcangeli.
8 * /proc/sysvipc/shm support (c) 1999 Dragos Acostachioaie <dragos@iname.com>
9 * BIGMEM support, Andrea Arcangeli <andrea@suse.de>
10 * SMP thread shm, Jean-Luc Boyard <jean-luc.boyard@siemens.fr>
11 * HIGHMEM support, Ingo Molnar <mingo@redhat.com>
12 * Make shmmax, shmall, shmmni sysctl'able, Christoph Rohland <cr@sap.com>
13 * Shared /dev/zero support, Kanoj Sarcar <kanoj@sgi.com>
14 * Move the mm functionality over to mm/shmem.c, Christoph Rohland <cr@sap.com>
16 * support for audit of ipc object properties and permission changes
17 * Dustin Kirkland <dustin.kirkland@us.ibm.com>
21 * Pavel Emelianov <xemul@openvz.org>
24 #include <linux/slab.h>
26 #include <linux/hugetlb.h>
27 #include <linux/shm.h>
28 #include <linux/init.h>
29 #include <linux/file.h>
30 #include <linux/mman.h>
31 #include <linux/shmem_fs.h>
32 #include <linux/security.h>
33 #include <linux/syscalls.h>
34 #include <linux/audit.h>
35 #include <linux/capability.h>
36 #include <linux/ptrace.h>
37 #include <linux/seq_file.h>
38 #include <linux/mutex.h>
39 #include <linux/nsproxy.h>
40 #include <linux/mount.h>
42 #include <asm/uaccess.h>
46 struct shm_file_data {
48 struct ipc_namespace *ns;
50 const struct vm_operations_struct *vm_ops;
53 #define shm_file_data(file) (*((struct shm_file_data **)&(file)->private_data))
55 static const struct file_operations shm_file_operations;
56 static struct vm_operations_struct shm_vm_ops;
58 static struct ipc_ids init_shm_ids;
60 #define shm_ids(ns) (*((ns)->ids[IPC_SHM_IDS]))
62 #define shm_lock(ns, id) \
63 ((struct shmid_kernel*)ipc_lock(&shm_ids(ns),id))
64 #define shm_unlock(shp) \
65 ipc_unlock(&(shp)->shm_perm)
66 #define shm_get(ns, id) \
67 ((struct shmid_kernel*)ipc_get(&shm_ids(ns),id))
68 #define shm_buildid(ns, id, seq) \
69 ipc_buildid(&shm_ids(ns), id, seq)
71 static int newseg (struct ipc_namespace *ns, key_t key,
72 int shmflg, size_t size);
73 static void shm_open(struct vm_area_struct *vma);
74 static void shm_close(struct vm_area_struct *vma);
75 static void shm_destroy (struct ipc_namespace *ns, struct shmid_kernel *shp);
77 static int sysvipc_shm_proc_show(struct seq_file *s, void *it);
80 static void __ipc_init __shm_init_ns(struct ipc_namespace *ns, struct ipc_ids *ids)
82 ns->ids[IPC_SHM_IDS] = ids;
83 ns->shm_ctlmax = SHMMAX;
84 ns->shm_ctlall = SHMALL;
85 ns->shm_ctlmni = SHMMNI;
90 static void do_shm_rmid(struct ipc_namespace *ns, struct shmid_kernel *shp)
93 shp->shm_perm.mode |= SHM_DEST;
94 /* Do not find it any more */
95 shp->shm_perm.key = IPC_PRIVATE;
102 int shm_init_ns(struct ipc_namespace *ns)
106 ids = kmalloc(sizeof(struct ipc_ids), GFP_KERNEL);
110 __shm_init_ns(ns, ids);
114 void shm_exit_ns(struct ipc_namespace *ns)
117 struct shmid_kernel *shp;
119 mutex_lock(&shm_ids(ns).mutex);
120 for (i = 0; i <= shm_ids(ns).max_id; i++) {
121 shp = shm_lock(ns, i);
125 do_shm_rmid(ns, shp);
127 mutex_unlock(&shm_ids(ns).mutex);
129 ipc_fini_ids(ns->ids[IPC_SHM_IDS]);
130 kfree(ns->ids[IPC_SHM_IDS]);
131 ns->ids[IPC_SHM_IDS] = NULL;
135 void __init shm_init (void)
137 __shm_init_ns(&init_ipc_ns, &init_shm_ids);
138 ipc_init_proc_interface("sysvipc/shm",
139 " key shmid perms size cpid lpid nattch uid gid cuid cgid atime dtime ctime\n",
140 IPC_SHM_IDS, sysvipc_shm_proc_show);
143 static inline int shm_checkid(struct ipc_namespace *ns,
144 struct shmid_kernel *s, int id)
146 if (ipc_checkid(&shm_ids(ns), &s->shm_perm, id))
151 static inline struct shmid_kernel *shm_rmid(struct ipc_namespace *ns, int id)
153 return (struct shmid_kernel *)ipc_rmid(&shm_ids(ns), id);
156 static inline int shm_addid(struct ipc_namespace *ns, struct shmid_kernel *shp)
158 return ipc_addid(&shm_ids(ns), &shp->shm_perm, ns->shm_ctlmni);
163 /* This is called by fork, once for every shm attach. */
164 static void shm_open(struct vm_area_struct *vma)
166 struct file *file = vma->vm_file;
167 struct shm_file_data *sfd = shm_file_data(file);
168 struct shmid_kernel *shp;
170 shp = shm_lock(sfd->ns, sfd->id);
172 shp->shm_atim = get_seconds();
173 shp->shm_lprid = current->tgid;
179 * shm_destroy - free the struct shmid_kernel
181 * @shp: struct to free
183 * It has to be called with shp and shm_ids.mutex locked,
184 * but returns with shp unlocked and freed.
186 static void shm_destroy(struct ipc_namespace *ns, struct shmid_kernel *shp)
188 ns->shm_tot -= (shp->shm_segsz + PAGE_SIZE - 1) >> PAGE_SHIFT;
189 shm_rmid(ns, shp->id);
191 if (!is_file_hugepages(shp->shm_file))
192 shmem_lock(shp->shm_file, 0, shp->mlock_user);
194 user_shm_unlock(shp->shm_file->f_path.dentry->d_inode->i_size,
196 fput (shp->shm_file);
197 security_shm_free(shp);
202 * remove the attach descriptor vma.
203 * free memory for segment if it is marked destroyed.
204 * The descriptor has already been removed from the current->mm->mmap list
205 * and will later be kfree()d.
207 static void shm_close(struct vm_area_struct *vma)
209 struct file * file = vma->vm_file;
210 struct shm_file_data *sfd = shm_file_data(file);
211 struct shmid_kernel *shp;
212 struct ipc_namespace *ns = sfd->ns;
214 mutex_lock(&shm_ids(ns).mutex);
215 /* remove from the list of attaches of the shm segment */
216 shp = shm_lock(ns, sfd->id);
218 shp->shm_lprid = current->tgid;
219 shp->shm_dtim = get_seconds();
221 if(shp->shm_nattch == 0 &&
222 shp->shm_perm.mode & SHM_DEST)
223 shm_destroy(ns, shp);
226 mutex_unlock(&shm_ids(ns).mutex);
229 struct page *shm_nopage(struct vm_area_struct *vma, unsigned long address,
232 struct file *file = vma->vm_file;
233 struct shm_file_data *sfd = shm_file_data(file);
235 return sfd->vm_ops->nopage(vma, address, type);
239 int shm_set_policy(struct vm_area_struct *vma, struct mempolicy *new)
241 struct file *file = vma->vm_file;
242 struct shm_file_data *sfd = shm_file_data(file);
244 if (sfd->vm_ops->set_policy)
245 err = sfd->vm_ops->set_policy(vma, new);
249 struct mempolicy *shm_get_policy(struct vm_area_struct *vma, unsigned long addr)
251 struct file *file = vma->vm_file;
252 struct shm_file_data *sfd = shm_file_data(file);
253 struct mempolicy *pol = NULL;
255 if (sfd->vm_ops->get_policy)
256 pol = sfd->vm_ops->get_policy(vma, addr);
258 pol = vma->vm_policy;
263 static int shm_mmap(struct file * file, struct vm_area_struct * vma)
265 struct shm_file_data *sfd = shm_file_data(file);
268 ret = sfd->file->f_op->mmap(sfd->file, vma);
271 sfd->vm_ops = vma->vm_ops;
272 vma->vm_ops = &shm_vm_ops;
278 static int shm_release(struct inode *ino, struct file *file)
280 struct shm_file_data *sfd = shm_file_data(file);
283 shm_file_data(file) = NULL;
289 static unsigned long shm_get_unmapped_area(struct file *file,
290 unsigned long addr, unsigned long len, unsigned long pgoff,
293 struct shm_file_data *sfd = shm_file_data(file);
294 return sfd->file->f_op->get_unmapped_area(sfd->file, addr, len, pgoff,
298 #define shm_get_unmapped_area NULL
301 static const struct file_operations shm_file_operations = {
303 .release = shm_release,
304 .get_unmapped_area = shm_get_unmapped_area,
307 static struct vm_operations_struct shm_vm_ops = {
308 .open = shm_open, /* callback for a new vm-area open */
309 .close = shm_close, /* callback for when the vm-area is released */
310 .nopage = shm_nopage,
311 #if defined(CONFIG_NUMA)
312 .set_policy = shm_set_policy,
313 .get_policy = shm_get_policy,
317 static int newseg (struct ipc_namespace *ns, key_t key, int shmflg, size_t size)
320 struct shmid_kernel *shp;
321 int numpages = (size + PAGE_SIZE -1) >> PAGE_SHIFT;
326 if (size < SHMMIN || size > ns->shm_ctlmax)
329 if (ns->shm_tot + numpages > ns->shm_ctlall)
332 shp = ipc_rcu_alloc(sizeof(*shp));
336 shp->shm_perm.key = key;
337 shp->shm_perm.mode = (shmflg & S_IRWXUGO);
338 shp->mlock_user = NULL;
340 shp->shm_perm.security = NULL;
341 error = security_shm_alloc(shp);
347 if (shmflg & SHM_HUGETLB) {
348 /* hugetlb_zero_setup takes care of mlock user accounting */
349 file = hugetlb_zero_setup(size);
350 shp->mlock_user = current->user;
352 int acctflag = VM_ACCOUNT;
354 * Do not allow no accounting for OVERCOMMIT_NEVER, even
357 if ((shmflg & SHM_NORESERVE) &&
358 sysctl_overcommit_memory != OVERCOMMIT_NEVER)
360 sprintf (name, "SYSV%08x", key);
361 file = shmem_file_setup(name, size, acctflag);
363 error = PTR_ERR(file);
368 id = shm_addid(ns, shp);
372 shp->shm_cprid = current->tgid;
374 shp->shm_atim = shp->shm_dtim = 0;
375 shp->shm_ctim = get_seconds();
376 shp->shm_segsz = size;
378 shp->id = shm_buildid(ns, id, shp->shm_perm.seq);
379 shp->shm_file = file;
381 ns->shm_tot += numpages;
388 security_shm_free(shp);
393 asmlinkage long sys_shmget (key_t key, size_t size, int shmflg)
395 struct shmid_kernel *shp;
397 struct ipc_namespace *ns;
399 ns = current->nsproxy->ipc_ns;
401 mutex_lock(&shm_ids(ns).mutex);
402 if (key == IPC_PRIVATE) {
403 err = newseg(ns, key, shmflg, size);
404 } else if ((id = ipc_findkey(&shm_ids(ns), key)) == -1) {
405 if (!(shmflg & IPC_CREAT))
408 err = newseg(ns, key, shmflg, size);
409 } else if ((shmflg & IPC_CREAT) && (shmflg & IPC_EXCL)) {
412 shp = shm_lock(ns, id);
414 if (shp->shm_segsz < size)
416 else if (ipcperms(&shp->shm_perm, shmflg))
419 int shmid = shm_buildid(ns, id, shp->shm_perm.seq);
420 err = security_shm_associate(shp, shmflg);
426 mutex_unlock(&shm_ids(ns).mutex);
431 static inline unsigned long copy_shmid_to_user(void __user *buf, struct shmid64_ds *in, int version)
435 return copy_to_user(buf, in, sizeof(*in));
440 ipc64_perm_to_ipc_perm(&in->shm_perm, &out.shm_perm);
441 out.shm_segsz = in->shm_segsz;
442 out.shm_atime = in->shm_atime;
443 out.shm_dtime = in->shm_dtime;
444 out.shm_ctime = in->shm_ctime;
445 out.shm_cpid = in->shm_cpid;
446 out.shm_lpid = in->shm_lpid;
447 out.shm_nattch = in->shm_nattch;
449 return copy_to_user(buf, &out, sizeof(out));
462 static inline unsigned long copy_shmid_from_user(struct shm_setbuf *out, void __user *buf, int version)
467 struct shmid64_ds tbuf;
469 if (copy_from_user(&tbuf, buf, sizeof(tbuf)))
472 out->uid = tbuf.shm_perm.uid;
473 out->gid = tbuf.shm_perm.gid;
474 out->mode = tbuf.shm_perm.mode;
480 struct shmid_ds tbuf_old;
482 if (copy_from_user(&tbuf_old, buf, sizeof(tbuf_old)))
485 out->uid = tbuf_old.shm_perm.uid;
486 out->gid = tbuf_old.shm_perm.gid;
487 out->mode = tbuf_old.shm_perm.mode;
496 static inline unsigned long copy_shminfo_to_user(void __user *buf, struct shminfo64 *in, int version)
500 return copy_to_user(buf, in, sizeof(*in));
505 if(in->shmmax > INT_MAX)
506 out.shmmax = INT_MAX;
508 out.shmmax = (int)in->shmmax;
510 out.shmmin = in->shmmin;
511 out.shmmni = in->shmmni;
512 out.shmseg = in->shmseg;
513 out.shmall = in->shmall;
515 return copy_to_user(buf, &out, sizeof(out));
522 static void shm_get_stat(struct ipc_namespace *ns, unsigned long *rss,
530 for (i = 0; i <= shm_ids(ns).max_id; i++) {
531 struct shmid_kernel *shp;
534 shp = shm_get(ns, i);
538 inode = shp->shm_file->f_path.dentry->d_inode;
540 if (is_file_hugepages(shp->shm_file)) {
541 struct address_space *mapping = inode->i_mapping;
542 *rss += (HPAGE_SIZE/PAGE_SIZE)*mapping->nrpages;
544 struct shmem_inode_info *info = SHMEM_I(inode);
545 spin_lock(&info->lock);
546 *rss += inode->i_mapping->nrpages;
547 *swp += info->swapped;
548 spin_unlock(&info->lock);
553 asmlinkage long sys_shmctl (int shmid, int cmd, struct shmid_ds __user *buf)
555 struct shm_setbuf setbuf;
556 struct shmid_kernel *shp;
558 struct ipc_namespace *ns;
560 if (cmd < 0 || shmid < 0) {
565 version = ipc_parse_version(&cmd);
566 ns = current->nsproxy->ipc_ns;
568 switch (cmd) { /* replace with proc interface ? */
571 struct shminfo64 shminfo;
573 err = security_shm_shmctl(NULL, cmd);
577 memset(&shminfo,0,sizeof(shminfo));
578 shminfo.shmmni = shminfo.shmseg = ns->shm_ctlmni;
579 shminfo.shmmax = ns->shm_ctlmax;
580 shminfo.shmall = ns->shm_ctlall;
582 shminfo.shmmin = SHMMIN;
583 if(copy_shminfo_to_user (buf, &shminfo, version))
585 /* reading a integer is always atomic */
586 err= shm_ids(ns).max_id;
593 struct shm_info shm_info;
595 err = security_shm_shmctl(NULL, cmd);
599 memset(&shm_info,0,sizeof(shm_info));
600 mutex_lock(&shm_ids(ns).mutex);
601 shm_info.used_ids = shm_ids(ns).in_use;
602 shm_get_stat (ns, &shm_info.shm_rss, &shm_info.shm_swp);
603 shm_info.shm_tot = ns->shm_tot;
604 shm_info.swap_attempts = 0;
605 shm_info.swap_successes = 0;
606 err = shm_ids(ns).max_id;
607 mutex_unlock(&shm_ids(ns).mutex);
608 if(copy_to_user (buf, &shm_info, sizeof(shm_info))) {
613 err = err < 0 ? 0 : err;
619 struct shmid64_ds tbuf;
621 memset(&tbuf, 0, sizeof(tbuf));
622 shp = shm_lock(ns, shmid);
626 } else if(cmd==SHM_STAT) {
628 if (shmid > shm_ids(ns).max_id)
630 result = shm_buildid(ns, shmid, shp->shm_perm.seq);
632 err = shm_checkid(ns, shp,shmid);
638 if (ipcperms (&shp->shm_perm, S_IRUGO))
640 err = security_shm_shmctl(shp, cmd);
643 kernel_to_ipc64_perm(&shp->shm_perm, &tbuf.shm_perm);
644 tbuf.shm_segsz = shp->shm_segsz;
645 tbuf.shm_atime = shp->shm_atim;
646 tbuf.shm_dtime = shp->shm_dtim;
647 tbuf.shm_ctime = shp->shm_ctim;
648 tbuf.shm_cpid = shp->shm_cprid;
649 tbuf.shm_lpid = shp->shm_lprid;
650 tbuf.shm_nattch = shp->shm_nattch;
652 if(copy_shmid_to_user (buf, &tbuf, version))
661 shp = shm_lock(ns, shmid);
666 err = shm_checkid(ns, shp,shmid);
670 err = audit_ipc_obj(&(shp->shm_perm));
674 if (!capable(CAP_IPC_LOCK)) {
676 if (current->euid != shp->shm_perm.uid &&
677 current->euid != shp->shm_perm.cuid)
679 if (cmd == SHM_LOCK &&
680 !current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur)
684 err = security_shm_shmctl(shp, cmd);
689 struct user_struct * user = current->user;
690 if (!is_file_hugepages(shp->shm_file)) {
691 err = shmem_lock(shp->shm_file, 1, user);
693 shp->shm_perm.mode |= SHM_LOCKED;
694 shp->mlock_user = user;
697 } else if (!is_file_hugepages(shp->shm_file)) {
698 shmem_lock(shp->shm_file, 0, shp->mlock_user);
699 shp->shm_perm.mode &= ~SHM_LOCKED;
700 shp->mlock_user = NULL;
708 * We cannot simply remove the file. The SVID states
709 * that the block remains until the last person
710 * detaches from it, then is deleted. A shmat() on
711 * an RMID segment is legal in older Linux and if
712 * we change it apps break...
714 * Instead we set a destroyed flag, and then blow
715 * the name away when the usage hits zero.
717 mutex_lock(&shm_ids(ns).mutex);
718 shp = shm_lock(ns, shmid);
722 err = shm_checkid(ns, shp, shmid);
726 err = audit_ipc_obj(&(shp->shm_perm));
730 if (current->euid != shp->shm_perm.uid &&
731 current->euid != shp->shm_perm.cuid &&
732 !capable(CAP_SYS_ADMIN)) {
737 err = security_shm_shmctl(shp, cmd);
741 do_shm_rmid(ns, shp);
742 mutex_unlock(&shm_ids(ns).mutex);
748 if (copy_shmid_from_user (&setbuf, buf, version)) {
752 mutex_lock(&shm_ids(ns).mutex);
753 shp = shm_lock(ns, shmid);
757 err = shm_checkid(ns, shp,shmid);
760 err = audit_ipc_obj(&(shp->shm_perm));
763 err = audit_ipc_set_perm(0, setbuf.uid, setbuf.gid, setbuf.mode);
767 if (current->euid != shp->shm_perm.uid &&
768 current->euid != shp->shm_perm.cuid &&
769 !capable(CAP_SYS_ADMIN)) {
773 err = security_shm_shmctl(shp, cmd);
777 shp->shm_perm.uid = setbuf.uid;
778 shp->shm_perm.gid = setbuf.gid;
779 shp->shm_perm.mode = (shp->shm_perm.mode & ~S_IRWXUGO)
780 | (setbuf.mode & S_IRWXUGO);
781 shp->shm_ctim = get_seconds();
794 mutex_unlock(&shm_ids(ns).mutex);
803 * Fix shmaddr, allocate descriptor, map shm, add attach descriptor to lists.
805 * NOTE! Despite the name, this is NOT a direct system call entrypoint. The
806 * "raddr" thing points to kernel space, and there has to be a wrapper around
809 long do_shmat(int shmid, char __user *shmaddr, int shmflg, ulong *raddr)
811 struct shmid_kernel *shp;
819 unsigned long user_addr;
820 struct ipc_namespace *ns;
821 struct shm_file_data *sfd;
828 else if ((addr = (ulong)shmaddr)) {
829 if (addr & (SHMLBA-1)) {
830 if (shmflg & SHM_RND)
831 addr &= ~(SHMLBA-1); /* round down */
833 #ifndef __ARCH_FORCE_SHMLBA
834 if (addr & ~PAGE_MASK)
838 flags = MAP_SHARED | MAP_FIXED;
840 if ((shmflg & SHM_REMAP))
846 if (shmflg & SHM_RDONLY) {
851 prot = PROT_READ | PROT_WRITE;
852 acc_mode = S_IRUGO | S_IWUGO;
853 f_mode = FMODE_READ | FMODE_WRITE;
855 if (shmflg & SHM_EXEC) {
861 * We cannot rely on the fs check since SYSV IPC does have an
862 * additional creator id...
864 ns = current->nsproxy->ipc_ns;
865 shp = shm_lock(ns, shmid);
869 err = shm_checkid(ns, shp,shmid);
874 if (ipcperms(&shp->shm_perm, acc_mode))
877 err = security_shm_shmat(shp, shmaddr, shmflg);
881 path.dentry = dget(shp->shm_file->f_path.dentry);
882 path.mnt = mntget(shp->shm_file->f_path.mnt);
884 size = i_size_read(path.dentry->d_inode);
888 sfd = kzalloc(sizeof(*sfd), GFP_KERNEL);
893 file = get_empty_filp();
897 file->f_op = &shm_file_operations;
898 file->private_data = sfd;
900 file->f_mapping = shp->shm_file->f_mapping;
901 file->f_mode = f_mode;
903 sfd->ns = get_ipc_ns(ns);
904 sfd->file = shp->shm_file;
907 down_write(¤t->mm->mmap_sem);
908 if (addr && !(shmflg & SHM_REMAP)) {
910 if (find_vma_intersection(current->mm, addr, addr + size))
913 * If shm segment goes below stack, make sure there is some
914 * space left for the stack to grow (at least 4 pages).
916 if (addr < current->mm->start_stack &&
917 addr > current->mm->start_stack - size - PAGE_SIZE * 5)
921 user_addr = do_mmap (file, addr, size, prot, flags, 0);
924 if (IS_ERR_VALUE(user_addr))
925 err = (long)user_addr;
927 up_write(¤t->mm->mmap_sem);
932 mutex_lock(&shm_ids(ns).mutex);
933 shp = shm_lock(ns, shmid);
936 if(shp->shm_nattch == 0 &&
937 shp->shm_perm.mode & SHM_DEST)
938 shm_destroy(ns, shp);
941 mutex_unlock(&shm_ids(ns).mutex);
958 asmlinkage long sys_shmat(int shmid, char __user *shmaddr, int shmflg)
963 err = do_shmat(shmid, shmaddr, shmflg, &ret);
966 force_successful_syscall_return();
971 * detach and kill segment if marked destroyed.
972 * The work is done in shm_close.
974 asmlinkage long sys_shmdt(char __user *shmaddr)
976 struct mm_struct *mm = current->mm;
977 struct vm_area_struct *vma, *next;
978 unsigned long addr = (unsigned long)shmaddr;
980 int retval = -EINVAL;
982 if (addr & ~PAGE_MASK)
985 down_write(&mm->mmap_sem);
988 * This function tries to be smart and unmap shm segments that
989 * were modified by partial mlock or munmap calls:
990 * - It first determines the size of the shm segment that should be
991 * unmapped: It searches for a vma that is backed by shm and that
992 * started at address shmaddr. It records it's size and then unmaps
994 * - Then it unmaps all shm vmas that started at shmaddr and that
995 * are within the initially determined size.
996 * Errors from do_munmap are ignored: the function only fails if
997 * it's called with invalid parameters or if it's called to unmap
998 * a part of a vma. Both calls in this function are for full vmas,
999 * the parameters are directly copied from the vma itself and always
1000 * valid - therefore do_munmap cannot fail. (famous last words?)
1003 * If it had been mremap()'d, the starting address would not
1004 * match the usual checks anyway. So assume all vma's are
1005 * above the starting address given.
1007 vma = find_vma(mm, addr);
1010 next = vma->vm_next;
1013 * Check if the starting address would match, i.e. it's
1014 * a fragment created by mprotect() and/or munmap(), or it
1015 * otherwise it starts at this address with no hassles.
1017 if ((vma->vm_ops == &shm_vm_ops) &&
1018 (vma->vm_start - addr)/PAGE_SIZE == vma->vm_pgoff) {
1021 size = vma->vm_file->f_path.dentry->d_inode->i_size;
1022 do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start);
1024 * We discovered the size of the shm segment, so
1025 * break out of here and fall through to the next
1026 * loop that uses the size information to stop
1027 * searching for matching vma's.
1037 * We need look no further than the maximum address a fragment
1038 * could possibly have landed at. Also cast things to loff_t to
1039 * prevent overflows and make comparisions vs. equal-width types.
1041 size = PAGE_ALIGN(size);
1042 while (vma && (loff_t)(vma->vm_end - addr) <= size) {
1043 next = vma->vm_next;
1045 /* finding a matching vma now does not alter retval */
1046 if ((vma->vm_ops == &shm_vm_ops) &&
1047 (vma->vm_start - addr)/PAGE_SIZE == vma->vm_pgoff)
1049 do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start);
1053 up_write(&mm->mmap_sem);
1057 #ifdef CONFIG_PROC_FS
1058 static int sysvipc_shm_proc_show(struct seq_file *s, void *it)
1060 struct shmid_kernel *shp = it;
1063 #define SMALL_STRING "%10d %10d %4o %10u %5u %5u %5d %5u %5u %5u %5u %10lu %10lu %10lu\n"
1064 #define BIG_STRING "%10d %10d %4o %21u %5u %5u %5d %5u %5u %5u %5u %10lu %10lu %10lu\n"
1066 if (sizeof(size_t) <= sizeof(int))
1067 format = SMALL_STRING;
1069 format = BIG_STRING;
1070 return seq_printf(s, format,