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From: Bijan Mottahedeh <[email protected]>
To: Jens Axboe <[email protected]>
Cc: [email protected]
Subject: Re: [RFC 1/2] io_uring: disallow overlapping ranges for buffer registration
Date: Fri, 12 Jun 2020 11:22:38 -0700	[thread overview]
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>

On 6/12/2020 8:16 AM, Jens Axboe wrote:
> On 6/11/20 8:23 PM, Bijan Mottahedeh wrote:
>> Buffer registration is expensive in terms of cpu/mem overhead and there
>> seems no good reason to allow overlapping ranges.
> There's also no good reason to disallow it imho, so not sure we should
> be doing that.
>

My concern was about a malicious user without CAP_IPC_LOCK abusing its 
memlock limit and repeatedly register the same buffer as that would tie 
up cpu/mem resources to pin up to 1TB of memory, but maybe the argument 
is that the user should have not been granted that large of memlock 
limit?  Also, without any restrictions, there are a huge number of ways 
overlapping ranges could be specified, creating a very large validation 
matrix.  What the use cases for that flexibility are though, I don't know.

--bijan

  reply	other threads:[~2020-06-12 18:24 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-12  2:23 [RFC 0/2] io_uring: disallow overlapping ranges for buffer registration Bijan Mottahedeh
2020-06-12  2:23 ` [RFC 1/2] " Bijan Mottahedeh
2020-06-12 15:16   ` Jens Axboe
2020-06-12 18:22     ` Bijan Mottahedeh [this message]
2020-06-14 15:56       ` Jens Axboe
2020-06-12  2:23 ` [RFC 2/2] io_uring: report pinned memory usage Bijan Mottahedeh
2020-06-12 15:16   ` Jens Axboe
2020-06-12 15:19     ` Jens Axboe
2020-06-12 15:50       ` Jens Axboe
2020-06-13  4:43       ` Bijan Mottahedeh
2020-06-14 15:57         ` Jens Axboe

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