+ mm-mmap-not-necessary-to-check-mapping-separately.patch added to -mm tree

+ mm-mmap-not-necessary-to-check-mapping-separately.patch added to -mm tree

[akpm]

The patch titled
     Subject: mm/mmap: not necessary to check mapping separately
has been added to the -mm tree.  Its filename is
     mm-mmap-not-necessary-to-check-mapping-separately.patch

This patch should soon appear at
    https://ozlabs.org/~akpm/mmots/broken-out/mm-mmap-not-necessary-to-check-mapping-separately.patch
and later at
    https://ozlabs.org/~akpm/mmotm/broken-out/mm-mmap-not-necessary-to-check-mapping-separately.patch

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------------------------------------------------------
From: Wei Yang <richard.weiyang@linux.alibaba.com>
Subject: mm/mmap: not necessary to check mapping separately

*root* with type of struct rb_root_cached is an element of *mapping*
with type of struct address_space. This implies when we have a valid
*root* it must be a part of valid *mapping*.

So we can merge these two checks together to make the code more easy to
read and to save some cpu cycles.

Link: https://lkml.kernel.org/r/20200913133631.37781-1-richard.weiyang@linux.alibaba.com
Signed-off-by: Wei Yang <richard.weiyang@linux.alibaba.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/mmap.c |    3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

--- a/mm/mmap.c~mm-mmap-not-necessary-to-check-mapping-separately
+++ a/mm/mmap.c
@@ -895,10 +895,9 @@ again:
 			anon_vma_interval_tree_post_update_vma(next);
 		anon_vma_unlock_write(anon_vma);
 	}
-	if (mapping)
-		i_mmap_unlock_write(mapping);
 
 	if (root) {
+		i_mmap_unlock_write(mapping);
 		uprobe_mmap(vma);
 
 		if (adjust_next)
_

Patches currently in -mm which might be from richard.weiyang@linux.alibaba.com are

mm-mmap-rename-__vma_unlink_common-to-__vma_unlink.patch
mm-mmap-leverage-vma_rb_erase_ignore-to-implement-vma_rb_erase.patch
mm-mmap-leave-adjust_next-as-virtual-address-instead-of-page-frame-number.patch
mm-mmap-not-necessary-to-check-mapping-separately.patch
mm-mmap-check-on-file-instead-of-the-rb_root_cached-of-its-address_space.patch
mm-hugetlb-not-necessary-to-coalesce-regions-recursively.patch
mm-hugetlb-remove-vm_bug_onnrg-in-get_file_region_entry_from_cache.patch
mm-hugetlb-use-list_splice-to-merge-two-list-at-once.patch
mm-hugetlb-count-file_region-to-be-added-when-regions_needed-=-null.patch
mm-hugetlb-a-page-from-buddy-is-not-on-any-list.patch
mm-hugetlb-narrow-the-hugetlb_lock-protection-area-during-preparing-huge-page.patch
mm-hugetlb-take-the-free-hpage-during-the-iteration-directly.patch
mm-hugetlb-take-the-free-hpage-during-the-iteration-directly-v4.patch
mm-page_reporting-drop-stale-list-head-check-in-page_reporting_cycle.patch
bitops-simplify-get_count_order_long.patch
bitops-use-the-same-mechanism-for-get_count_order.patch