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Sun, 15 Feb 2026 22:21:17 -0800 (PST) Date: Mon, 16 Feb 2026 14:21:12 +0800 From: Kairui Song To: Barry Song <21cnbao@gmail.com> 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 Subject: Re: [PATCH v3 2/3] mm, swap: reduce indention for hibernate allocation helper Message-ID: References: <20260216-hibernate-perf-v3-0-74e025091145@tencent.com> <20260216-hibernate-perf-v3-2-74e025091145@tencent.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Rspamd-Server: rspam12 X-Stat-Signature: 9hjn9ymroq7h4tmp7nw19rw5ejkc45yn X-Rspamd-Queue-Id: BC40E40008 X-Rspam-User: X-HE-Tag: 1771222879-323468 X-HE-Meta: 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 ASCzDLQE Fp0KjRrFR+56NpyZDOArNiVbOzRhDW+BGkofYrR003kWOedWCtZfvFHCpYPzfoOTX8h/NkFiyfqNimAKpU8YcO5JAl0Skvl0kTVtGA40awOgFrsJo4h6dkEYIWJ0MxKTfxZVc47JTF1h/Uf2CUW+ptBtWbMCfoDIz8UFvGgMzuZXp+zeOqO7tioQ4+3sJ++ncBiuASs+IVhcqae4dAsyVCcR3qqOAMX4/vMmwQENzyMIDn0IpIBdA2ZD+KIfJ1+EOnOtuRazDk7Ci42HzvKmGA+Iae8Q3NcDn+NOeouevXw+l+Xe2D4Hlxs7BxEZNu3zol+vPo2bkkz3Oy3A7ScWQ0ziIFqGOZ2Ymb6/7CzMSk7rlEJhR3hCs6djuAHUSrG7iyXoiR6JThJFYRtYy6ze2JnfDng1RX7qOkRaf7anurcToLbtpJ/eeGin8YZTGgo4H8ooyjWB4/E3qivWJxCnv43+8Coly8vSG2VMi9gTgVvxEh8mF8MmX9IL61lhh89mMmZ60 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 07:20:49AM +0800, Barry Song wrote: > On Mon, Feb 16, 2026 at 3:00 AM 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 type) > > > > /* 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. I'll post a v4 later today combined with your another suggestion. Thanks!