linux-kernel - [PATCH v3 2/3] mm: vmalloc: Switch to find_unlink_vmap_area() in vm_unmap

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Message-Id: <20221222190022.134380-2-urezki@gmail.com>
Date:   Thu, 22 Dec 2022 20:00:21 +0100
From:   "Uladzislau Rezki (Sony)" <urezki@...il.com>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     linux-mm@...ck.org, LKML <linux-kernel@...r.kernel.org>,
        Baoquan He <bhe@...hat.com>,
        Lorenzo Stoakes <lstoakes@...il.com>,
        Christoph Hellwig <hch@...radead.org>,
        Matthew Wilcox <willy@...radead.org>,
        Nicholas Piggin <npiggin@...il.com>,
        Uladzislau Rezki <urezki@...il.com>,
        Oleksiy Avramchenko <oleksiy.avramchenko@...y.com>,
        Christoph Hellwig <hch@....de>
Subject: [PATCH v3 2/3] mm: vmalloc: Switch to find_unlink_vmap_area() in vm_unmap_ram()

Switch from find_vmap_area() to find_unlink_vmap_area() to prevent
a double access to the vmap_area_lock: one for finding area, second
time is for unlinking from a tree.

Reviewed-by: Christoph Hellwig <hch@....de>
Signed-off-by: Uladzislau Rezki (Sony) <urezki@...il.com>
---
 mm/vmalloc.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index eb91ecaa7277..70e5000b9d68 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -2252,7 +2252,7 @@ void vm_unmap_ram(const void *mem, unsigned int count)
 		return;
 	}
 
-	va = find_vmap_area(addr);
+	va = find_unlink_vmap_area(addr);
 	BUG_ON(!va);
 	debug_check_no_locks_freed((void *)va->va_start,
 				    (va->va_end - va->va_start));
-- 
2.30.2