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Subject[PATCH] MM: use helpers for rlimits
Date
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
or ACCESS_ONCE if not applicable.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: linux-mm@kvack.org
Cc: Andrew Morton <akpm@linux-foundation.org>
---
mm/filemap.c | 2 +-
mm/mlock.c | 12 ++++++------
mm/mmap.c | 13 +++++++------
mm/mremap.c | 2 +-
4 files changed, 15 insertions(+), 14 deletions(-)
diff --git a/mm/filemap.c b/mm/filemap.c
index 96ac6b0..4450b75 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1950,7 +1950,7 @@ 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 2b8335a..8f4e2df 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 ee22989..7805ac5 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;
@@ -1599,7 +1599,7 @@ 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 */
@@ -1607,7 +1607,8 @@ 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;
}
@@ -2074,7 +2075,7 @@ 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;
@@ -2288,7 +2289,7 @@ 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 8451908..4c4c803 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;
--
1.6.5.7


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