From: liusongtang <liusongtang@huawei.com>
To: <akpm@linux-foundation.org>
Cc: <liusongtang@huawei.com>, <linux-mm@kvack.org>,
<linux-kernel@vger.kernel.org>, <nixiaoming@huawei.com>,
<young.liuyang@huawei.com>, <wangkefeng@huawei.com>
Subject: [PATCH] mm/mprotect: reduce Committed_AS if memory protection is changed to PROT_NONE
Date: Tue, 26 Apr 2022 19:27:05 +0800 [thread overview]
Message-ID: <20220426112705.3323-1-liusongtang@huawei.com> (raw)
If PROT_WRITE is set, the size of vm area will be added to Committed_AS.
However, if memory protection is changed to PROT_NONE,
the corresponding physical memory will not be used, but Committed_AS still
count the size of the PROT_NONE memory.
This patch reduce Committed_AS and free the corresponding memory if
memory protection is changed to PROT_NONE.
Signed-off-by: liusongtang <liusongtang@huawei.com>
---
mm/mprotect.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/mm/mprotect.c b/mm/mprotect.c
index b69ce7a..c3121e6 100644
--- a/mm/mprotect.c
+++ b/mm/mprotect.c
@@ -497,6 +497,12 @@ mprotect_fixup(struct vm_area_struct *vma, struct vm_area_struct **pprev,
}
success:
+ if ((newflags & (VM_READ | VM_WRITE | VM_EXEC | VM_LOCKED | VM_ACCOUNT)) == VM_ACCOUNT) {
+ zap_page_range(vma, start, end - start);
+ newflags &= ~VM_ACCOUNT;
+ vm_unacct_memory((end - start) >> PAGE_SHIFT);
+ }
+
/*
* vm_flags and vm_page_prot are protected by the mmap_lock
* held in write mode.
--
2.12.3
next reply other threads:[~2022-04-26 11:27 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-26 11:27 liusongtang [this message]
2022-04-26 20:34 ` [PATCH] mm/mprotect: reduce Committed_AS if memory protection is changed to PROT_NONE Andrew Morton
2022-04-27 6:34 ` liusongtang
2022-05-03 18:35 ` David Hildenbrand
2022-04-30 15:41 ` [mm/mprotect] 5e1e18b334: kvm-unit-tests.eventinj.fail kernel test robot
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