mm-fix-race-between-madv_free-reclaim-and-blkdev-direct-io-read-v4

mm-fix-race-between-madv_free-reclaim-and-blkdev-direct-io-read-v4

v4: - fixed Fixes: tag to first support, after tests on v4.5;
      updated commit message/reproducer section with results.
    - tested on v5.17-rc3 and v4.5.
    - shorten comment line; remove inner braces in the check.
      (Thanks: Christoph Hellwig <hch@infradead.org>)
    - clarify comment about __remove_mapping()
      (Thanks: Yu Zhao <yuzhao@google.com>)

Link: https://lkml.kernel.org/r/20220209202659.183418-1-mfo@canonical.com
Fixes: 854e9ed09ded ("mm: support madvise(MADV_FREE)")
Signed-off-by: Mauricio Faria de Oliveira <mfo@canonical.com>
Reviewed-by: "Huang, Ying" <ying.huang@intel.com>
Cc: Dan Hill <daniel.hill@canonical.com>
Cc: Dan Streetman <dan.streetman@canonical.com>
Cc: Dongdong Tao <dongdong.tao@canonical.com>
Cc: Gavin Guo <gavin.guo@canonical.com>
Cc: Gerald Yang <gerald.yang@canonical.com>
Cc: Heitor Alves de Siqueira <halves@canonical.com>
Cc: Ioanna Alifieraki <ioanna-maria.alifieraki@canonical.com>
Cc: Jay Vosburgh <jay.vosburgh@canonical.com>
Cc: Matthew Ruffell <matthew.ruffell@canonical.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Ponnuvel Palaniyappan <ponnuvel.palaniyappan@canonical.com>
Cc: Yang Shi <shy828301@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>