+ mm-use-helper-function-mapping_allow_writable.patch added to -mm tree

+ mm-use-helper-function-mapping_allow_writable.patch added to -mm tree

[akpm]

The patch titled
     Subject: mm: use helper function mapping_allow_writable()
has been added to the -mm tree.  Its filename is
     mm-use-helper-function-mapping_allow_writable.patch

This patch should soon appear at
    https://ozlabs.org/~akpm/mmots/broken-out/mm-use-helper-function-mapping_allow_writable.patch
and later at
    https://ozlabs.org/~akpm/mmotm/broken-out/mm-use-helper-function-mapping_allow_writable.patch

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------------------------------------------------------
From: Miaohe Lin <linmiaohe@huawei.com>
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@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Cc: Christian Brauner <christian.brauner@ubuntu.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Christian Kellner <christian@kellner.me>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Adrian Reber <areber@redhat.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Aleksa Sarai <cyphar@cyphar.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 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
@@ -558,7 +558,7 @@ 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);
_

Patches currently in -mm which might be from linmiaohe@huawei.com are

mm-swap-fix-confusing-comment-in-release_pages.patch
mm-memcontrol-correct-the-comment-of-mem_cgroup_iter.patch
mm-page_counter-correct-the-obsolete-func-name-in-the-comment-of-page_counter_try_charge.patch
mm-use-helper-function-mapping_allow_writable.patch
mm-vmstat-use-helper-macro-abs.patch
mm-fix-some-broken-comments.patch
mm-migrate-avoid-possible-unnecessary-process-right-check-in-kernel_move_pages.patch