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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: 48b4800 ("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]>
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