linux-kernel - [PATCH 5.15 540/779] mm/mmap.c: fix missing call to vm_unacct_memory in mmap

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Message-Id: <20220815180400.396206986@linuxfoundation.org>
Date:   Mon, 15 Aug 2022 20:03:04 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Miaohe Lin <linmiaohe@...wei.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.15 540/779] mm/mmap.c: fix missing call to vm_unacct_memory in mmap_region

From: Miaohe Lin <linmiaohe@...wei.com>

[ Upstream commit 7f82f922319ede486540e8746769865b9508d2c2 ]

Since the beginning, charged is set to 0 to avoid calling vm_unacct_memory
twice because vm_unacct_memory will be called by above unmap_region.  But
since commit 4f74d2c8e827 ("vm: remove 'nr_accounted' calculations from
the unmap_vmas() interfaces"), unmap_region doesn't call vm_unacct_memory
anymore.  So charged shouldn't be set to 0 now otherwise the calling to
paired vm_unacct_memory will be missed and leads to imbalanced account.

Link: https://lkml.kernel.org/r/20220618082027.43391-1-linmiaohe@huawei.com
Fixes: 4f74d2c8e827 ("vm: remove 'nr_accounted' calculations from the unmap_vmas() interfaces")
Signed-off-by: Miaohe Lin <linmiaohe@...wei.com>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 mm/mmap.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/mm/mmap.c b/mm/mmap.c
index 6bb553ed5c55..031fca1a7c65 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1878,7 +1878,6 @@ unsigned long mmap_region(struct file *file, unsigned long addr,
 
 	/* Undo any partial mapping done by a device driver. */
 	unmap_region(mm, vma, prev, vma->vm_start, vma->vm_end);
-	charged = 0;
 	if (vm_flags & VM_SHARED)
 		mapping_unmap_writable(file->f_mapping);
 free_vma:
-- 
2.35.1