From: Miaohe Lin <linmiaohe@xxxxxxxxxx>
Subject: mm: use helper function mapping_allow_writable()
Commit 4bb5f5d9395b ("mm: allow drivers to prevent new writable mappings")
changed i_mmap_writable from unsigned int to atomic_t and add the helper
function mapping_allow_writable() to atomic_inc i_mmap_writable. But it
forgot to use this helper function in dup_mmap() and __vma_link_file().
Link: https://lkml.kernel.org/r/20200917112736.7789-1-linmiaohe@xxxxxxxxxx
Signed-off-by: Miaohe Lin <linmiaohe@xxxxxxxxxx>
Cc: Christian Brauner <christian.brauner@xxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
Cc: Christian Kellner <christian@xxxxxxxxxx>
Cc: Suren Baghdasaryan <surenb@xxxxxxxxxx>
Cc: Adrian Reber <areber@xxxxxxxxxx>
Cc: Shakeel Butt <shakeelb@xxxxxxxxxx>
Cc: Aleksa Sarai <cyphar@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/fork.c | 2 +-
mm/mmap.c | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)
--- a/kernel/fork.c~mm-use-helper-function-mapping_allow_writable
+++ a/kernel/fork.c
@@ -559,7 +559,7 @@ static __latent_entropy int dup_mmap(str
atomic_dec(&inode->i_writecount);
i_mmap_lock_write(mapping);
if (tmp->vm_flags & VM_SHARED)
- atomic_inc(&mapping->i_mmap_writable);
+ mapping_allow_writable(mapping);
flush_dcache_mmap_lock(mapping);
/* insert tmp into the share list, just after mpnt */
vma_interval_tree_insert_after(tmp, mpnt,
--- a/mm/mmap.c~mm-use-helper-function-mapping_allow_writable
+++ a/mm/mmap.c
@@ -621,7 +621,7 @@ static void __vma_link_file(struct vm_ar
if (vma->vm_flags & VM_DENYWRITE)
atomic_dec(&file_inode(file)->i_writecount);
if (vma->vm_flags & VM_SHARED)
- atomic_inc(&mapping->i_mmap_writable);
+ mapping_allow_writable(mapping);
flush_dcache_mmap_lock(mapping);
vma_interval_tree_insert(vma, &mapping->i_mmap);
_
