From: Davidlohr Bueso <dave@stgolabs.net>
Date: Sat, 13 Dec 2014 00:54:42 +0000 (-0800)
Subject: mm/memory.c: share the i_mmap_rwsem
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=c8475d144abb1e62958cc5ec281d2a9e161c1946;p=GitHub%2FLineageOS%2FG12%2Fandroid_kernel_amlogic_linux-4.9.git

mm/memory.c: share the i_mmap_rwsem

The unmap_mapping_range family of functions do the unmapping of user pages
(ultimately via zap_page_range_single) without touching the actual
interval tree, thus share the lock.

Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Acked-by: Hugh Dickins <hughd@google.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

diff --git a/mm/memory.c b/mm/memory.c
index 039fab699a1a..5afdb5b8d4e2 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2377,12 +2377,12 @@ void unmap_mapping_range(struct address_space *mapping,
 		details.last_index = ULONG_MAX;
 
 
-	i_mmap_lock_write(mapping);
+	i_mmap_lock_read(mapping);
 	if (unlikely(!RB_EMPTY_ROOT(&mapping->i_mmap)))
 		unmap_mapping_range_tree(&mapping->i_mmap, &details);
 	if (unlikely(!list_empty(&mapping->i_mmap_nonlinear)))
 		unmap_mapping_range_list(&mapping->i_mmap_nonlinear, &details);
-	i_mmap_unlock_write(mapping);
+	i_mmap_unlock_read(mapping);
 }
 EXPORT_SYMBOL(unmap_mapping_range);