From: Wei Yang <richard.weiyang@linux.alibaba.com>
Date: Tue, 13 Oct 2020 23:54:07 +0000 (-0700)
Subject: mm/mmap: check on file instead of the rb_root_cached of its address_space
X-Git-Url: http://git.osdn.net/view?a=commitdiff_plain;h=0fc48a6e213ab8e4033d26bd8333ee8558f210f6;p=uclinux-h8%2Flinux.git

mm/mmap: check on file instead of the rb_root_cached of its address_space

In __vma_adjust(), we do the check on *root* to decide whether to adjust
the address_space.  It seems to be more meaningful to do the check on
*file* itself.  This means we are adjusting some data because it is a file
backed vma.

Since we seem to assume the address_space is valid if it is a file backed
vma, let's just replace *root* with *file* here.

Signed-off-by: Wei Yang <richard.weiyang@linux.alibaba.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Link: https://lkml.kernel.org/r/20200913133631.37781-2-richard.weiyang@linux.alibaba.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

diff --git a/mm/mmap.c b/mm/mmap.c
index 295197b75cb0..19cd69524837 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -823,7 +823,7 @@ again:
 			anon_vma_interval_tree_pre_update_vma(next);
 	}
 
-	if (root) {
+	if (file) {
 		flush_dcache_mmap_lock(mapping);
 		vma_interval_tree_remove(vma, root);
 		if (adjust_next)
@@ -844,7 +844,7 @@ again:
 		next->vm_pgoff += adjust_next >> PAGE_SHIFT;
 	}
 
-	if (root) {
+	if (file) {
 		if (adjust_next)
 			vma_interval_tree_insert(next, root);
 		vma_interval_tree_insert(vma, root);
@@ -896,7 +896,7 @@ again:
 		anon_vma_unlock_write(anon_vma);
 	}
 
-	if (root) {
+	if (file) {
 		i_mmap_unlock_write(mapping);
 		uprobe_mmap(vma);