linux-kernel - Re: [PATCH v2 0/6] gfs2: Fix mmap + page fault deadlocks

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Message-ID: <YPXdHGAH7FbXnAj6@zeniv-ca.linux.org.uk>
Date:   Mon, 19 Jul 2021 20:14:20 +0000
From:   Al Viro <viro@...iv.linux.org.uk>
To:     Andreas Gruenbacher <agruenba@...hat.com>
Cc:     Linus Torvalds <torvalds@...ux-foundation.org>,
        Jan Kara <jack@...e.cz>, Matthew Wilcox <willy@...radead.org>,
        Christoph Hellwig <hch@...radead.org>,
        cluster-devel@...hat.com, linux-fsdevel@...r.kernel.org,
        linux-kernel@...r.kernel.org, ocfs2-devel@....oracle.com
Subject: Re: [PATCH v2 0/6] gfs2: Fix mmap + page fault deadlocks

On Mon, Jul 19, 2021 at 12:39:26AM +0200, Andreas Gruenbacher wrote:
> Hi Linus et al.,
> 
> here's an update to the gfs2 mmap + page faults fix that implements
> Linus's suggestion of disabling page faults while we're holding the
> inode glock.
> 
> This passes fstests except for test generic/095, which fails due to an
> independent bug in the iov_iter code.  I'm currently trying to get
> initial feedback from Al and Christoph on that.
> 
> Any feedback would be welcome.

What tree is that against?  Because in mainline your #5 sure as hell
won't apply...

There uio.h has
enum iter_type {
        /* iter types */
        ITER_IOVEC,
        ITER_KVEC,
        ITER_BVEC,
        ITER_PIPE,
        ITER_XARRAY,
        ITER_DISCARD,
};

and your series assumes

enum iter_type {
        /* iter types */
        ITER_IOVEC = 4,
        ITER_KVEC = 8,
        ITER_BVEC = 16,
        ITER_PIPE = 32,
        ITER_DISCARD = 64,
};

What had that been tested with?