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Message-ID: <9493177b-c435-9adc-cdfc-e45b91f02e77@redhat.com>
Date:   Wed, 31 May 2023 09:46:37 +0200
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Subject: Re: [PATCH -V3 4/5] swap: remove get/put_swap_device() in
 __swap_duplicate()
Content-Language: en-US
To:     Huang Ying <ying.huang@intel.com>,
        Andrew Morton <akpm@linux-foundation.org>
Cc:     linux-mm@kvack.org, linux-kernel@vger.kernel.org,
        Yosry Ahmed <yosryahmed@google.com>,
        Hugh Dickins <hughd@google.com>,
        Johannes Weiner <hannes@cmpxchg.org>,
        Matthew Wilcox <willy@infradead.org>,
        Michal Hocko <mhocko@suse.com>,
        Minchan Kim <minchan@kernel.org>,
        Tim Chen <tim.c.chen@linux.intel.com>,
        Yang Shi <shy828301@gmail.com>, Yu Zhao <yuzhao@google.com>,
        Chris Li <chrisl@kernel.org>
References: <20230529061355.125791-1-ying.huang@intel.com>
 <20230529061355.125791-5-ying.huang@intel.com>
From:   David Hildenbrand <david@redhat.com>
Organization: Red Hat
In-Reply-To: <20230529061355.125791-5-ying.huang@intel.com>
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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@intel.com>
> Reviewed-by: Yosry Ahmed <yosryahmed@google.com>
> Cc: David Hildenbrand <david@redhat.com>
> 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>
> Cc: Chris Li <chrisl@kernel.org>
> ---

Reviewed-by: David Hildenbrand <david@redhat.com>

-- 
Thanks,

David / dhildenb