linux-kernel - [PATCH 14/17] memremap: simplify duplicate region handling in devm_memremap

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Message-Id: <20171229075406.1936-15-hch@lst.de>
Date:   Fri, 29 Dec 2017 08:54:03 +0100
From:   Christoph Hellwig <hch@....de>
To:     Dan Williams <dan.j.williams@...el.com>
Cc:     Jérôme Glisse <jglisse@...hat.com>,
        Logan Gunthorpe <logang@...tatee.com>,
        Michal Hocko <mhocko@...nel.org>, linux-nvdimm@...ts.01.org,
        linuxppc-dev@...ts.ozlabs.org, x86@...nel.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH 14/17] memremap: simplify duplicate region handling in devm_memremap_pages

__radix_tree_insert already checks for duplicates and returns -EEXIST in
that case, so remove the duplicate (and racy) duplicates check.

Signed-off-by: Christoph Hellwig <hch@....de>
Reviewed-by: Logan Gunthorpe <logang@...tatee.com>
---
 kernel/memremap.c | 11 -----------
 1 file changed, 11 deletions(-)

diff --git a/kernel/memremap.c b/kernel/memremap.c
index b09517439dec..12e78528fea4 100644
--- a/kernel/memremap.c
+++ b/kernel/memremap.c
@@ -396,17 +396,6 @@ void *devm_memremap_pages(struct device *dev, struct resource *res,
 	align_end = align_start + align_size - 1;
 
 	foreach_order_pgoff(res, order, pgoff) {
-		struct dev_pagemap *dup;
-
-		rcu_read_lock();
-		dup = find_dev_pagemap(res->start + PFN_PHYS(pgoff));
-		rcu_read_unlock();
-		if (dup) {
-			dev_err(dev, "%s: %pr collides with mapping for %s\n",
-					__func__, res, dev_name(dup->dev));
-			error = -EBUSY;
-			break;
-		}
 		error = __radix_tree_insert(&pgmap_radix,
 				PHYS_PFN(res->start) + pgoff, order, page_map);
 		if (error) {
-- 
2.14.2