mm, dev_pagemap: Do not clear ->mapping on final put

MEMORY_DEVICE_FS_DAX relies on typical page semantics whereby ->mapping
is only ever cleared by truncation, not final put.

Without this fix dax pages may forget their mapping association at the
end of every page pin event.

Move this atypical behavior that HMM wants into the HMM ->page_free()
callback.

Cc: <[email protected]>
Cc: Jan Kara <[email protected]>
Cc: Jérôme Glisse <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Ross Zwisler <[email protected]>
Fixes: d2c997c0f145 ("fs, dax: use page->mapping...")
Signed-off-by: Dan Williams <[email protected]>
Acked-by: Jérôme Glisse <[email protected]>
Signed-off-by: Dave Jiang <[email protected]>

0 files changed, 0 insertions, 0 deletions