linux-kernel - Re: Change in splice() behaviour after 5.10?

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Message-ID: <7F3B484F-9555-486A-B19A-5A8EB6442988@kernel.org>
Date: Mon, 03 Jun 2024 22:43:31 -0700
From: Kees Cook <kees@...nel.org>
To: Christoph Hellwig <hch@....de>, Terry Tritton <terry.tritton@...aro.org>
CC: hch@....de, "ttritton@...gle.com" <ttritton@...gle.com>, edliaw@...gle.com,
 keescook@...omium.org, linux-kernel@...r.kernel.org,
 linux-fsdevel@...r.kernel.org, Jens Axboe <axboe@...nel.dk>
Subject: Re: Change in splice() behaviour after 5.10?

On June 3, 2024 9:50:30 PM PDT, Christoph Hellwig <hch@....de> wrote:
>On Mon, Jun 03, 2024 at 10:59:15AM +0100, Terry Tritton wrote:
>> Hi,
>> We've found a change in behaviour while testing the splice07 LTP test.
>> In versions before 5.10 the test will hang on certain combinations but after
>> 5.10 the splice call will return.
>> I bisected the change to the following commit:
>>     36e2c7421f02a22f71c9283e55fdb672a9eb58e7
>>     fs: don't allow splice read/write without explicit ops
>> 
>> There has been some discussion on the LTP github page already:
>>     https://github.com/linux-test-project/ltp/issues/1156
>
>In that case the return probably is an error because epoll doesn't
>support read_iter/write_iter and thus completely expected.
>
>If the underlying bug hasn't been fix in the mean time that probably
>means it will be back if Jens' conversion of all misc file operations
>to the iter based ones every gets merged.
>
>If you are interested more in this please discuss it on the relevant
>mailing lists instead of in private mail.

Eh? LKML is in CC...

I've added fsdevel and Jens now too, though. 

-Kees

-- 
Kees Cook