mm/mmap.c: fix missing call to vm_unacct_memory in mmap_region

stable inclusion
from stable-v4.19.256
commit f84c69bbb3ccc544f0023c4dbbdf922c09b5d80b
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I5Q0SQ
CVE: NA

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[ 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 4f74d2c8 ("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: 4f74d2c8 ("vm: remove 'nr_accounted' calculations from the unmap_vmas() interfaces")
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Signed-off-by: Andrew Morton...