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Date: Tue, 10 Oct 2017 12:44:21 -0700
From: Andrew Morton <akpm@linux-foundation.org>
To: Matthew Wilcox <willy@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
        Johannes Thumshirn <jthumshirn@suse.de>, linux-fsdevel@vger.kernel.org,
        linux-nvdimm@lists.01.org,
        OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>,
        Ross Zwisler <ross.zwisler@linux.intel.com>,
        Toshi Kani <toshi.kani@hpe.com>, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] Fix mpage_writepage() for pages with buffers
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On Fri, 6 Oct 2017 14:15:41 -0700 Matthew Wilcox <willy@infradead.org> wrote:

> When using FAT on a block device which supports rw_page, we can hit
> BUG_ON(!PageLocked(page)) in try_to_free_buffers().  This is because we
> call clean_buffers() after unlocking the page we've written.  Introduce a
> new clean_page_buffers() which cleans all buffers associated with a page
> and call it from within bdev_write_page().

This is all pretty mature code (isn't it?).  Any idea why this bug
popped up now?