linux-kernel - [RFC PATCH 3/5] mm: mremap: Allow new

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Message-ID: <20241210213050.2839638-4-bgeffon@google.com>
Date: Tue, 10 Dec 2024 16:30:48 -0500
From: Brian Geffon <bgeffon@...gle.com>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>, Jann Horn <jannh@...gle.com>, 
	Vlastimil Babka <vbabka@...e.cz>, "Liam R. Howlett" <Liam.Howlett@...cle.com>, linux-mm@...ck.org, 
	Marco Vanotti <mvanotti@...gle.com>, linux-kernel@...r.kernel.org, 
	Brian Geffon <bgeffon@...gle.com>
Subject: [RFC PATCH 3/5] mm: mremap: Allow new_addr to be specified as a hint

When using MREMAP_MAYMOVE previously the new_addr was ignored unless
the user specified MREMAP_FIXED. This change will allow it to be
used as a hint in that situation similar to how mmap(2) behaves.

get_unmapped_area() will handle page aligning the new address hint.

Signed-off-by: Brian Geffon <bgeffon@...gle.com>
---
 mm/mremap.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/mremap.c b/mm/mremap.c
index fdc1b0f1b38e..1d2522fba0ef 100644
--- a/mm/mremap.c
+++ b/mm/mremap.c
@@ -1205,7 +1205,7 @@ SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len,
 		if (vma->vm_flags & VM_MAYSHARE)
 			map_flags |= MAP_SHARED;
 
-		new_addr = get_unmapped_area(vma->vm_file, 0, new_len,
+		new_addr = get_unmapped_area(vma->vm_file, new_addr, new_len,
 					vma->vm_pgoff +
 					((addr - vma->vm_start) >> PAGE_SHIFT),
 					map_flags);
-- 
2.47.0.338.g60cca15819-goog