Hi, Minchan, When I review the patchset from Kairui, I checked the code to skip swap cache in do_swap_page() for swap device with SWP_SYNCHRONOUS_IO. Is the following race possible? Where a page is swapped out to a swap device with SWP_SYNCHRONOUS_IO and the swap count is 1. Then 2 threads of the process runs on CPU0 and CPU1 as below. CPU0 is running do_swap_page(). CPU0 CPU1 ---- ---- swap_cache_get_folio() check sync io and swap count alloc folio swap_readpage() folio_lock_or_retry() swap in the swap entry write page swap out to same swap entry pte_offset_map_lock() check pte_same() swap_free() <-- new content lost! set_pte_at() <-- stale page! folio_unlock() pte_unmap_unlock() Do I miss anything? -- Best Regards, Huang, Ying
