Re: [PATCH v2] dma-buf: set SB_I_NOEXEC and SB_I_NODEV on the pseudo filesystem

[John Hubbard]

On 5/24/26 10:55 PM, Christoph Hellwig wrote:
> On Fri, May 22, 2026 at 06:11:17PM -0700, John Hubbard wrote:
>> The dma-buf pseudo filesystem dispenses S_ANON_INODE inodes via
>> alloc_anon_inode() but never sets SB_I_NOEXEC on its superblock.
>> Since commit 1e7ab6f67824 ("anon_inode: rework assertions") in 6.17,
>> path_noexec() warns on exactly that combination, so an mmap() on any
>> dma-buf fd trips the warning:
> 
> Just as last time this came up, we really should set this higher up.
> There isn't really a reason why pseudofses should not set SB_I_NOEXEC
> by default.
> 

Ha, I see now that there is some history to this.

After looking at the email history and the code, it does seem like
the time is right to do that. I'm testing out a tiny series to set
these flags in init_pseudo(), and then to *not* redundantly set them
elsewhere, I'll post it shortly.

thanks,
-- 
John Hubbard