mm/zsmalloc.c: migration can leave pages in ZS_EMPTY indefinitely

In zs_page_migrate() we call putback_zspage() after we have finished
migrating all pages in this zspage.  However, the return value is
ignored.  If a zs_free() races in between zs_page_isolate() and
zs_page_migrate(), freeing the last object in the zspage,
putback_zspage() will leave the page in ZS_EMPTY for potentially an
unbounded amount of time.

To fix this, we need to do the same thing as zs_page_putback() does:
schedule free_work to occur.

To avoid duplicated code, move the sequence to a new
putback_zspage_deferred() function which both zs_page_migrate() and
zs_page_putback() call.

Link: http://lkml.kernel.org/r/[email protected]
Fixes: 48b4800a1c6a ("zsmalloc: page migration support")
Signed-off-by: Henry Burns <[email protected]>
Reviewed-by: Sergey Senozhatsky <[email protected]>
Cc: Henry Burns <[email protected]>
Cc: Minchan Kim <[email protected]>
Cc: Shakeel Butt <[email protected]>
Cc: Jonathan Adams <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

0 files changed, 0 insertions, 0 deletions