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Date:   Fri, 18 Feb 2022 04:24:20 +0000
From:   Matthew Wilcox <willy@infradead.org>
To:     Theodore Ts'o <tytso@mit.edu>
Cc:     Lee Jones <lee.jones@linaro.org>, linux-ext4@vger.kernel.org,
        Christoph Hellwig <hch@lst.de>,
        Dave Chinner <dchinner@redhat.com>,
        Goldwyn Rodrigues <rgoldwyn@suse.com>,
        "Darrick J . Wong" <darrick.wong@oracle.com>,
        Bob Peterson <rpeterso@redhat.com>,
        Damien Le Moal <damien.lemoal@wdc.com>,
        Andreas Gruenbacher <agruenba@redhat.com>,
        Ritesh Harjani <riteshh@linux.ibm.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Johannes Thumshirn <jth@kernel.org>, linux-xfs@vger.kernel.org,
        linux-fsdevel@vger.kernel.org, cluster-devel@redhat.com,
        linux-kernel@vger.kernel.org
Subject: Re: [REPORT] kernel BUG at fs/ext4/inode.c:2620 - page_buffers()
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On Thu, Feb 17, 2022 at 09:54:30PM -0500, Theodore Ts'o wrote:
> process_vm_writev() uses [un]pin_user_pages_remote() which is the same
> interface uses for RDMA.  But it's not clear this is ever supposed to
> work for memory which is mmap'ed region backed by a file.
> pin_user_pages_remote() appears to assume that it is an anonymous
> region, since the get_user_pages functions in mm/gup.c don't call
> read_page() to read data into any pages that might not be mmaped in.

... it doesn't end up calling handle_mm_fault() in faultin_page()?