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From: David Hildenbrand <david@redhat.com>
To: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: "Liam R. Howlett" <Liam.Howlett@oracle.com>,
	Charan Teja Kalla <quic_charante@quicinc.com>,
	akpm@linux-foundation.org, shikemeng@huaweicloud.com,
	kasong@tencent.com, nphamcs@gmail.com, bhe@redhat.com,
	baohua@kernel.org, chrisl@kernel.org, linux-mm@kvack.org,
	linux-kernel@vger.kernel.org,
	Matthew Wilcox <willy@infradead.org>
Subject: Re: [PATCH] mm: swap: check for xa_zero_entry() on vma in swapoff path
Date: Mon, 11 Aug 2025 17:51:11 +0200	[thread overview]
Message-ID: <c63b9a78-6a39-42e1-8a72-b4ce4a7025b1@redhat.com> (raw)
In-Reply-To: <e7781de2-dd05-495a-9a40-7718f04adf0e@lucifer.local>

On 11.08.25 17:48, Lorenzo Stoakes wrote:
> On Mon, Aug 11, 2025 at 05:39:32PM +0200, David Hildenbrand wrote:
>>
>>>
>>> I could make a function that frees all new vmas and destroys the tree
>>> specifically for this failure state?
>>
>> I think the problem is that some page tables were already copied, so we
>> would have to zap them as well.
> 
> This shouldn't be too much more egregious?
> 
> The issues arise when it might be an OOM issue, but if it's a fatal signal we
> can take the time to clean up.
> 
>>
>> Maybe just factoring stuff from the exit_mmap() function could be one way to
>> do it.
> 
> Is exit_mmap() a problem here? Or maybe I don't understand what you're getting
> at.

We are dropping the write lock in between, allowing for these races.

-- 
Cheers,

David / dhildenb



  reply	other threads:[~2025-08-11 15:51 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-08-08  9:21 [PATCH] mm: swap: check for xa_zero_entry() on vma in swapoff path Charan Teja Kalla
2025-08-08 12:01 ` David Hildenbrand
2025-08-08 12:04   ` David Hildenbrand
2025-08-11  9:43     ` Charan Teja Kalla
2025-08-11 12:14       ` Lorenzo Stoakes
2025-08-11 13:03         ` David Hildenbrand
2025-08-11 13:08           ` Lorenzo Stoakes
2025-08-11 13:19             ` David Hildenbrand
2025-08-11 13:22               ` Lorenzo Stoakes
2025-08-11 15:17                 ` Liam R. Howlett
2025-08-11 15:39                   ` David Hildenbrand
2025-08-11 15:48                     ` Lorenzo Stoakes
2025-08-11 15:51                       ` David Hildenbrand [this message]
2025-08-11 15:48                     ` Liam R. Howlett
2025-08-11 12:07 ` Lorenzo Stoakes
2025-08-11 16:29   ` Charan Teja Kalla

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