linux-kernel - Re: [PATCH v2 bpf-next] mm: mmap: increase sockets maximum memory size pgoff for 32bits

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Date:   Tue, 13 Aug 2019 12:12:29 +0300
From:   Ivan Khoronzhuk <ivan.khoronzhuk@...aro.org>
To:     Magnus Karlsson <magnus.karlsson@...il.com>
Cc:     Björn Töpel <bjorn.topel@...el.com>,
        linux-mm@...ck.org, Xdp <xdp-newbies@...r.kernel.org>,
        Network Development <netdev@...r.kernel.org>,
        bpf <bpf@...r.kernel.org>, linux-kernel@...r.kernel.org,
        akpm@...ux-foundation.org, Alexei Starovoitov <ast@...nel.org>,
        "Karlsson, Magnus" <magnus.karlsson@...el.com>
Subject: Re: [PATCH v2 bpf-next] mm: mmap: increase sockets maximum memory
 size pgoff for 32bits

On Tue, Aug 13, 2019 at 10:02:54AM +0200, Magnus Karlsson wrote:
>On Mon, Aug 12, 2019 at 2:45 PM Ivan Khoronzhuk
><ivan.khoronzhuk@...aro.org> wrote:
>>
>> The AF_XDP sockets umem mapping interface uses XDP_UMEM_PGOFF_FILL_RING
>> and XDP_UMEM_PGOFF_COMPLETION_RING offsets. The offsets seems like are
>> established already and are part of configuration interface.
>>
>> But for 32-bit systems, while AF_XDP socket configuration, the values
>> are to large to pass maximum allowed file size verification.
>> The offsets can be tuned ofc, but instead of changing existent
>> interface - extend max allowed file size for sockets.
>
>Can you use mmap2() instead that takes a larger offset (2^44) even on
>32-bit systems?

That's for mmap2.

>
>/Magnus
>
>> Signed-off-by: Ivan Khoronzhuk <ivan.khoronzhuk@...aro.org>
>> ---
>>
>> Based on bpf-next/master
>>
>> v2..v1:
>>         removed not necessarily #ifdev as ULL and UL for 64 has same size
>>
>>  mm/mmap.c | 3 +++
>>  1 file changed, 3 insertions(+)
>>
>> diff --git a/mm/mmap.c b/mm/mmap.c
>> index 7e8c3e8ae75f..578f52812361 100644
>> --- a/mm/mmap.c
>> +++ b/mm/mmap.c
>> @@ -1358,6 +1358,9 @@ static inline u64 file_mmap_size_max(struct file *file, struct inode *inode)
>>         if (S_ISBLK(inode->i_mode))
>>                 return MAX_LFS_FILESIZE;
>>
>> +       if (S_ISSOCK(inode->i_mode))
>> +               return MAX_LFS_FILESIZE;
>> +
>>         /* Special "we do even unsigned file positions" case */
>>         if (file->f_mode & FMODE_UNSIGNED_OFFSET)
>>                 return 0;
>> --
>> 2.17.1
>>

-- 
Regards,
Ivan Khoronzhuk