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Subject: Re: [PATCH v1] mm: Enable suspend-only swap spaces
To:     Evan Green <evgreen@chromium.org>,
        Andrew Morton <akpm@linux-foundation.org>
Cc:     Alex Shi <alexs@kernel.org>, Alistair Popple <apopple@nvidia.com>,
        Jens Axboe <axboe@kernel.dk>,
        Johannes Weiner <hannes@cmpxchg.org>,
        Joonsoo Kim <iamjoonsoo.kim@lge.com>,
        "Matthew Wilcox (Oracle)" <willy@infradead.org>,
        Miaohe Lin <linmiaohe@huawei.com>,
        Minchan Kim <minchan@kernel.org>,
        Stephen Rothwell <sfr@canb.auug.org.au>,
        Vlastimil Babka <vbabka@suse.cz>, linux-kernel@vger.kernel.org,
        linux-mm@kvack.org
References: <20210630100432.v1.1.I09866d90c6de14f21223a03e9e6a31f8a02ecbaf@changeid>
From:   David Hildenbrand <david@redhat.com>
Organization: Red Hat
Message-ID: <c178b1f1-73ee-d5a8-dfda-b2d53aa8d83d@redhat.com>
Date:   Mon, 5 Jul 2021 09:44:30 +0200
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On 30.06.21 19:07, Evan Green wrote:
> Currently it's not possible to enable hibernation without also enabling
> generic swap for a given swap area. These two use cases are not the
> same. For example there may be users who want to enable hibernation,
> but whose drives don't have the write endurance for generic swap
> activities.
> 
> Add a new SWAP_FLAG_NOSWAP that adds a swap region but refuses to allow
> generic swapping to it. This region can still be wired up for use in
> suspend-to-disk activities, but will never have regular pages swapped to
> it.

Just to confirm: things like /proc/meminfo won't show this "swap that's 
not actually swap" as free/total swap, correct? Maybe it's worth 
spelling the expected system behavior out here.


-- 
Thanks,

David / dhildenb