From: Andrew Morton <akpm@linux-foundation.org>
To: Miaohe Lin <linmiaohe@huawei.com>
Cc: <linux-mm@kvack.org>, <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 1/3] mm/swapfile: make security_vm_enough_memory_mm() work as expected
Date: Mon, 30 May 2022 16:02:23 -0700 [thread overview]
Message-ID: <20220530160223.63ae3bdef7420f252d7366ed@linux-foundation.org> (raw)
In-Reply-To: <20220527092626.31883-2-linmiaohe@huawei.com>
On Fri, 27 May 2022 17:26:24 +0800 Miaohe Lin <linmiaohe@huawei.com> wrote:
> security_vm_enough_memory_mm() checks whether a process has enough memory
> to allocate a new virtual mapping. And total_swap_pages is considered as
> available memory while swapoff tries to make sure there's enough memory
> that can hold the swapped out memory. But total_swap_pages contains the
> swap space that is being swapoff. So security_vm_enough_memory_mm() will
> success even if there's no memory to hold the swapped out memory because
> total_swap_pages always greater than or equal to p->pages.
>
> In order to fix it, p->pages should be retracted from total_swap_pages
> first and then check whether there's enough memory for inuse swap pages.
User-visible impact?
If I'm understanding correctly, there's a risk that this fix will cause
existing setups to newly fail when attempting swapoff()?
next prev parent reply other threads:[~2022-05-30 23:02 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-27 9:26 [PATCH 0/3] A few fixup patches for swap Miaohe Lin
2022-05-27 9:26 ` [PATCH 1/3] mm/swapfile: make security_vm_enough_memory_mm() work as expected Miaohe Lin
2022-05-30 23:02 ` Andrew Morton [this message]
2022-05-31 2:40 ` Miaohe Lin
2022-05-27 9:26 ` [PATCH 2/3] mm/swapfile: avoid confusing swap cache statistics Miaohe Lin
2022-05-30 23:04 ` Andrew Morton
2022-05-31 2:55 ` Miaohe Lin
2022-05-31 12:58 ` David Hildenbrand
2022-06-01 2:11 ` Miaohe Lin
2022-06-01 7:53 ` David Hildenbrand
2022-06-02 7:29 ` Miaohe Lin
2022-06-02 8:41 ` David Hildenbrand
2022-06-06 3:14 ` Miaohe Lin
2022-05-27 9:26 ` [PATCH 3/3] mm/swapfile: fix possible data races of inuse_pages Miaohe Lin
2022-05-31 13:02 ` David Hildenbrand
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