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>

1 files changed, 7 insertions, 6 deletions

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;