mm: use rlimit helpers

Make sure compiler won't do weird things with limits.  E.g.  fetching them
twice may return 2 different values after writable limits are implemented.

I.e.  either use rlimit helpers added in
3e10e716abf3c71bdb5d86b8f507f9e72236c9cd ("resource: add helpers for
fetching rlimits") or ACCESS_ONCE if not applicable.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

4 files changed, 15 insertions, 14 deletions

diff --git a/mm/filemap.c b/mm/filemap.c
index 148b52a5bb7e..045b31c37653 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1986,7 +1986,7 @@ EXPORT_SYMBOL(iov_iter_single_seg_count);
 inline int generic_write_checks(struct file *file, loff_t *pos, size_t *count, int isblk)
 {
         struct inode *inode = file->f_mapping->host;
-        unsigned long limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur;
+        unsigned long limit = rlimit(RLIMIT_FSIZE);
 
         if (unlikely(*pos < 0))
                 return -EINVAL;
diff --git a/mm/mlock.c b/mm/mlock.c
index 2b8335a89400..8f4e2dfceec1 100644
--- a/mm/mlock.c
+++ b/mm/mlock.c
@@ -25,7 +25,7 @@ int can_do_mlock(void)
 {
         if (capable(CAP_IPC_LOCK))
                 return 1;
-        if (current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur != 0)
+        if (rlimit(RLIMIT_MEMLOCK) != 0)
                 return 1;
         return 0;
 }
@@ -487,7 +487,7 @@ SYSCALL_DEFINE2(mlock, unsigned long, start, size_t, len)
         locked = len >> PAGE_SHIFT;
         locked += current->mm->locked_vm;
 
-        lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur;
+        lock_limit = rlimit(RLIMIT_MEMLOCK);
         lock_limit >>= PAGE_SHIFT;
 
         /* check against resource limits */
@@ -550,7 +550,7 @@ SYSCALL_DEFINE1(mlockall, int, flags)
 
         down_write(&current->mm->mmap_sem);
 
-        lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur;
+        lock_limit = rlimit(RLIMIT_MEMLOCK);
         lock_limit >>= PAGE_SHIFT;
 
         ret = -ENOMEM;
@@ -584,7 +584,7 @@ int user_shm_lock(size_t size, struct user_struct *user)
         int allowed = 0;
 
         locked = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
-        lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur;
+        lock_limit = rlimit(RLIMIT_MEMLOCK);
         if (lock_limit == RLIM_INFINITY)
                 allowed = 1;
         lock_limit >>= PAGE_SHIFT;
@@ -618,12 +618,12 @@ int account_locked_memory(struct mm_struct *mm, struct rlimit *rlim,
 
         down_write(&mm->mmap_sem);
 
-        lim = rlim[RLIMIT_AS].rlim_cur >> PAGE_SHIFT;
+        lim = ACCESS_ONCE(rlim[RLIMIT_AS].rlim_cur) >> PAGE_SHIFT;
         vm   = mm->total_vm + pgsz;
         if (lim < vm)
                 goto out;
 
-        lim = rlim[RLIMIT_MEMLOCK].rlim_cur >> PAGE_SHIFT;
+        lim = ACCESS_ONCE(rlim[RLIMIT_MEMLOCK].rlim_cur) >> PAGE_SHIFT;
         vm   = mm->locked_vm + pgsz;
         if (lim < vm)
                 goto out;
diff --git a/mm/mmap.c b/mm/mmap.c
index c646618702cf..31656147128e 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -265,7 +265,7 @@ SYSCALL_DEFINE1(brk, unsigned long, brk)
          * segment grow beyond its set limit the in case where the limit is
          * not page aligned -Ram Gupta
          */
-        rlim = current->signal->rlim[RLIMIT_DATA].rlim_cur;
+        rlim = rlimit(RLIMIT_DATA);
         if (rlim < RLIM_INFINITY && (brk - mm->start_brk) +
                         (mm->end_data - mm->start_data) > rlim)
                 goto out;
@@ -967,7 +967,7 @@ unsigned long do_mmap_pgoff(struct file *file, unsigned long addr,
                 unsigned long locked, lock_limit;
                 locked = len >> PAGE_SHIFT;
                 locked += mm->locked_vm;
-                lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur;
+                lock_limit = rlimit(RLIMIT_MEMLOCK);
                 lock_limit >>= PAGE_SHIFT;
                 if (locked > lock_limit && !capable(CAP_IPC_LOCK))
                         return -EAGAIN;
@@ -1594,7 +1594,7 @@ static int acct_stack_growth(struct vm_area_struct *vma, unsigned long size, uns
                 return -ENOMEM;
 
         /* Stack limit test */
-        if (size > rlim[RLIMIT_STACK].rlim_cur)
+        if (size > ACCESS_ONCE(rlim[RLIMIT_STACK].rlim_cur))
                 return -ENOMEM;
 
         /* mlock limit tests */
@@ -1602,7 +1602,8 @@ static int acct_stack_growth(struct vm_area_struct *vma, unsigned long size, uns
                 unsigned long locked;
                 unsigned long limit;
                 locked = mm->locked_vm + grow;
-                limit = rlim[RLIMIT_MEMLOCK].rlim_cur >> PAGE_SHIFT;
+                limit = ACCESS_ONCE(rlim[RLIMIT_MEMLOCK].rlim_cur);
+                limit >>= PAGE_SHIFT;
                 if (locked > limit && !capable(CAP_IPC_LOCK))
                         return -ENOMEM;
         }
@@ -2067,7 +2068,7 @@ unsigned long do_brk(unsigned long addr, unsigned long len)
                 unsigned long locked, lock_limit;
                 locked = len >> PAGE_SHIFT;
                 locked += mm->locked_vm;
-                lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur;
+                lock_limit = rlimit(RLIMIT_MEMLOCK);
                 lock_limit >>= PAGE_SHIFT;
                 if (locked > lock_limit && !capable(CAP_IPC_LOCK))
                         return -EAGAIN;
@@ -2281,7 +2282,7 @@ int may_expand_vm(struct mm_struct *mm, unsigned long npages)
         unsigned long cur = mm->total_vm;       /* pages */
         unsigned long lim;
 
-        lim = current->signal->rlim[RLIMIT_AS].rlim_cur >> PAGE_SHIFT;
+        lim = rlimit(RLIMIT_AS) >> PAGE_SHIFT;
 
         if (cur + npages > lim)
                 return 0;
diff --git a/mm/mremap.c b/mm/mremap.c
index 845190898d59..4c4c803453f3 100644
--- a/mm/mremap.c
+++ b/mm/mremap.c
@@ -285,7 +285,7 @@ static struct vm_area_struct *vma_to_resize(unsigned long addr,
         if (vma->vm_flags & VM_LOCKED) {
                 unsigned long locked, lock_limit;
                 locked = mm->locked_vm << PAGE_SHIFT;
-                lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur;
+                lock_limit = rlimit(RLIMIT_MEMLOCK);
                 locked += new_len - old_len;
                 if (locked > lock_limit && !capable(CAP_IPC_LOCK))
                         goto Eagain;