Commit c07aee4f authored by Huang Ying's avatar Huang Ying Committed by Andrew Morton
Browse files

swap: remove get/put_swap_device() in __swap_duplicate() 

__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().

Link: https://lkml.kernel.org/r/20230529061355.125791-5-ying.huang@intel.com


Signed-off-by: default avatar"Huang, Ying" <ying.huang@intel.com>
Reviewed-by: default avatarYosry Ahmed <yosryahmed@google.com>
Reviewed-by: default avatarDavid Hildenbrand <david@redhat.com>
Reviewed-by: default avatarChris Li (Google) <chrisl@kernel.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Yu Zhao <yuzhao@google.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 3ecdeb0f

mm/swapfile.c

+1 −4
Original line number Diff line number Diff line
@@ -3265,9 +3265,7 @@ static int __swap_duplicate(swp_entry_t entry, unsigned char usage) 
	unsigned char has_cache;

	int err;



	p = get_swap_device(entry);

	if (!p)

		return -EINVAL;

	p = swp_swap_info(entry);



	offset = swp_offset(entry);

	ci = lock_cluster_or_swap_info(p, offset);
@@ -3314,7 +3312,6 @@ static int __swap_duplicate(swp_entry_t entry, unsigned char usage) 


unlock_out:

	unlock_cluster_or_swap_info(p, ci);

	put_swap_device(p);

	return err;

}