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Sun, 15 Feb 2026 23:37:29 -0800 (PST) MIME-Version: 1.0 References: <20260216-hibernate-perf-v3-0-74e025091145@tencent.com> <20260216-hibernate-perf-v3-2-74e025091145@tencent.com> In-Reply-To: From: Barry Song <21cnbao@gmail.com> Date: Mon, 16 Feb 2026 15:37:18 +0800 X-Gm-Features: AaiRm51YL07XwCLRpDnl1bzYmcZGhOriLqlRjp6yzM2ZWVDai3YuU-_kptZhK_U Message-ID: Subject: Re: [PATCH v3 2/3] mm, swap: reduce indention for hibernate allocation helper To: Kairui Song Cc: kasong@tencent.com, linux-mm@kvack.org, Andrew Morton , Chris Li , Kemeng Shi , Nhat Pham , Baoquan He , Carsten Grohmann , "Rafael J. Wysocki" , linux-kernel@vger.kernel.org, "open list:SUSPEND TO RAM" , Carsten Grohmann Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 5CF85100005 X-Stat-Signature: ai1q1y68hy8f4w7awqsz8bgaihfpb4hs X-Rspam-User: X-HE-Tag: 1771227450-483028 X-HE-Meta: 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 ji2bEpmt oLI60CP50BJEAR5cs2OPMAZI7WAXbl71M3X0GdFsIB0rVblQh7iOoWmKGfi5p4MLBxEiJuAzjhTSkDvh7p4rlY9RzJUyKVGKzBjEl+DudHuhdhFIjKQJwt17aP8QTgjz1coY+W4QQ8WTBxU5KoWjHk4PjRHRwYiYINGC6SHlndGqQT8toQenDadauWUnmlIn3iA8xN/Kxxh8QE8nYOCpw0gIobgIWk3xbazJQNLNW2o0RJqkafHenWzs5sCNr7uduhID9c72sJkgV6QX9K03KqIUa+ln/6EYrY3xy5ZTxerd+dhAF8mLQAo9D13qMQhD28McJ9eaIV8XfTunFtmczHyaNlymxIqjYSfL9yileYMeVlnnta9BarvkfRckVRsLGI5bK54NG1vp4ExLukx1j4HiwWj5h9e77WIzUwu6/TqiJ6ZkMn5fo04d38LHDlU+k9xhcF1qBuFxpFGn/1ir0zEz6eA== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, Feb 16, 2026 at 2:21=E2=80=AFPM Kairui Song wrot= e: > > On Mon, Feb 16, 2026 at 07:20:49AM +0800, Barry Song wrote: > > On Mon, Feb 16, 2026 at 3:00=E2=80=AFAM Kairui Song via B4 Relay > > wrote: > > > > > > From: Kairui Song > > > > > > It doesn't have to check the device flag, as the allocator will also > > > check the device flag and refuse to allocate if the device is not > > > writable. This might cause a trivial waste of CPU cycles of hibernate > > > allocation raced with swapoff, but that is very unlikely to happen. > > > Removing the check on the common path should be more helpful. > > > > > > Signed-off-by: Kairui Song > > > --- > > > mm/swapfile.c | 38 ++++++++++++++++++-------------------- > > > 1 file changed, 18 insertions(+), 20 deletions(-) > > > > > > diff --git a/mm/swapfile.c b/mm/swapfile.c > > > index 32e0e7545ab8..0d1b17c99221 100644 > > > --- a/mm/swapfile.c > > > +++ b/mm/swapfile.c > > > @@ -1936,27 +1936,25 @@ swp_entry_t swap_alloc_hibernation_slot(int t= ype) > > > > > > /* This is called for allocating swap entry, not cache */ > > > if (get_swap_device_info(si)) { > > > > > > I guess we could further reduce indentation by doing: > > if (!get_swap_device_info(si)) > > goto fail; > > > > Agree, I think we can make it even simpler by having: > > /* Return empty entry if device is not usable (swapoff or full) */ > if (!si || !get_swap_device_info(si)) > return entry; > > Then the `fail` label is also gone. Yes, this looks even nicer to me. :-) > > I'll post a v4 later today combined with your another suggestion. Thanks!