Re: [fuse-devel] fuse: trying to steal weird page

[Nikolaus Rath <Nikolaus@rath.org>]

On Jan 07 2019, Miklos Szeredi <miklos@szeredi.hu> wrote:
> On Wed, Dec 26, 2018 at 10:44 PM Nikolaus Rath <Nikolaus@rath.org> wrote:
>>
>> Hi,
>>
>> I am seeing relatively regular occurences of
>>
>> $ sudo dmesg | tail
>> [21929.138815] fuse: trying to steal weird page
>> [21929.138821] page=00000000a7dd2617 index=64 flags=17fffc0000000ad,
>> count=1, mapcount=0, mapping= (null)
>> [21930.647338] fuse: trying to steal weird page
>> [21930.647345] page=00000000a07f32af index=2848
>> flags=17fffc0000000ad, count=1, mapcount=0, mapping= (null)
>> [21932.338873] fuse: trying to steal weird page
>> [21932.338879] page=0000000067e3a012 index=64 flags=17fffc0000000ad,
>> count=1, mapcount=0, mapping= (null)
>> [21933.930703] fuse: trying to steal weird page
>> [21933.930710] page=00000000046feb25 index=845
>> flags=17fffc0000000ad, count=1, mapcount=0, mapping= (null)
>> [21936.163174] fuse: trying to steal weird page
>> [21936.163180] page=00000000fb80fe27 index=0 flags=17fffc0000000ad,
>> count=1, mapcount=0, mapping= (null)
>
> The page has the PG_dity and PG_waiters flags set which are
> incompatible with stealing.  page_cache_pipe_buf_steal() does
> apparently filter out dirty ones, so it's not a regular file that we
> are trying to streal the page from.  So the question is: what is the
> source of the splice()?
 
Hmm. I think it has to be a regular file. But as I mentioned in my other
email, I did have a race condition where fd's were closed
incorrectly. Is it possible that this also triggered the above,
i.e. that the fd was closed sometime during splice?


Best,
-Nikolaus

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