Re: [PATCH -V3 4/5] swap: remove get/put_swap_device() in __swap_duplicate()

From: David Hildenbrand
Date: Wed May 31 2023 - 03:47:35 EST

On 29.05.23 08:13, Huang Ying wrote:
__swap_duplicate() is called by

- swap_shmem_alloc(): the folio in swap cache is locked.

- copy_nonpresent_pte() -> swap_duplicate() and try_to_unmap_one() ->
swap_duplicate(): the page table lock is held.

- __read_swap_cache_async() -> swapcache_prepare(): enclosed with
get/put_swap_device() in __read_swap_cache_async() already.

So, it's safe to remove get/put_swap_device() in __swap_duplicate().

Signed-off-by: "Huang, Ying" <ying.huang@xxxxxxxxx>
Reviewed-by: Yosry Ahmed <yosryahmed@xxxxxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Minchan Kim <minchan@xxxxxxxxxx>
Cc: Tim Chen <tim.c.chen@xxxxxxxxxxxxxxx>
Cc: Yang Shi <shy828301@xxxxxxxxx>
Cc: Yu Zhao <yuzhao@xxxxxxxxxx>
Cc: Chris Li <chrisl@xxxxxxxxxx>

Reviewed-by: David Hildenbrand <david@xxxxxxxxxx>


David / dhildenb