1 files changed, 58 insertions, 18 deletions

diff --git a/mm/mmap.c b/mm/mmap.c
index 9d5968d1e8e3..fc41c0543d7f 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1324,6 +1324,35 @@ static inline int mlock_future_check(struct mm_struct *mm,
 	return 0;
 }
 
+static inline u64 file_mmap_size_max(struct file *file, struct inode *inode)
+{
+	if (S_ISREG(inode->i_mode))
+		return MAX_LFS_FILESIZE;
+
+	if (S_ISBLK(inode->i_mode))
+		return MAX_LFS_FILESIZE;
+
+	/* Special "we do even unsigned file positions" case */
+	if (file->f_mode & FMODE_UNSIGNED_OFFSET)
+		return 0;
+
+	/* Yes, random drivers might want more. But I'm tired of buggy drivers */
+	return ULONG_MAX;
+}
+
+static inline bool file_mmap_ok(struct file *file, struct inode *inode,
+				unsigned long pgoff, unsigned long len)
+{
+	u64 maxsize = file_mmap_size_max(file, inode);
+
+	if (maxsize && len > maxsize)
+		return false;
+	maxsize -= len;
+	if (pgoff > maxsize >> PAGE_SHIFT)
+		return false;
+	return true;
+}
+
 /*
  * The caller must hold down_write(&current->mm->mmap_sem).
  */
@@ -1409,6 +1438,9 @@ unsigned long do_mmap(struct file *file, unsigned long addr,
 		struct inode *inode = file_inode(file);
 		unsigned long flags_mask;
 
+		if (!file_mmap_ok(file, inode, pgoff, len))
+			return -EOVERFLOW;
+
 		flags_mask = LEGACY_MAP_MASK | file->f_op->mmap_supported_flags;
 
 		switch (flags & MAP_TYPE) {
@@ -3024,6 +3056,32 @@ void exit_mmap(struct mm_struct *mm)
 	/* mm's last user has gone, and its about to be pulled down */
 	mmu_notifier_release(mm);
 
+	if (unlikely(mm_is_oom_victim(mm))) {
+		/*
+		 * Manually reap the mm to free as much memory as possible.
+		 * Then, as the oom reaper does, set MMF_OOM_SKIP to disregard
+		 * this mm from further consideration.  Taking mm->mmap_sem for
+		 * write after setting MMF_OOM_SKIP will guarantee that the oom
+		 * reaper will not run on this mm again after mmap_sem is
+		 * dropped.
+		 *
+		 * Nothing can be holding mm->mmap_sem here and the above call
+		 * to mmu_notifier_release(mm) ensures mmu notifier callbacks in
+		 * __oom_reap_task_mm() will not block.
+		 *
+		 * This needs to be done before calling munlock_vma_pages_all(),
+		 * which clears VM_LOCKED, otherwise the oom reaper cannot
+		 * reliably test it.
+		 */
+		mutex_lock(&oom_lock);
+		__oom_reap_task_mm(mm);
+		mutex_unlock(&oom_lock);
+
+		set_bit(MMF_OOM_SKIP, &mm->flags);
+		down_write(&mm->mmap_sem);
+		up_write(&mm->mmap_sem);
+	}
+
 	if (mm->locked_vm) {
 		vma = mm->mmap;
 		while (vma) {
@@ -3045,24 +3103,6 @@ void exit_mmap(struct mm_struct *mm)
 	/* update_hiwater_rss(mm) here? but nobody should be looking */
 	/* Use -1 here to ensure all VMAs in the mm are unmapped */
 	unmap_vmas(&tlb, vma, 0, -1);
-
-	if (unlikely(mm_is_oom_victim(mm))) {
-		/*
-		 * Wait for oom_reap_task() to stop working on this
-		 * mm. Because MMF_OOM_SKIP is already set before
-		 * calling down_read(), oom_reap_task() will not run
-		 * on this "mm" post up_write().
-		 *
-		 * mm_is_oom_victim() cannot be set from under us
-		 * either because victim->mm is already set to NULL
-		 * under task_lock before calling mmput and oom_mm is
-		 * set not NULL by the OOM killer only if victim->mm
-		 * is found not NULL while holding the task_lock.
-		 */
-		set_bit(MMF_OOM_SKIP, &mm->flags);
-		down_write(&mm->mmap_sem);
-		up_write(&mm->mmap_sem);
-	}
 	free_pgtables(&tlb, vma, FIRST_USER_ADDRESS, USER_PGTABLES_CEILING);
 	tlb_finish_mmu(&tlb, 0, -1);