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Mon, 23 Mar 2026 23:49:57 -0700 (PDT) Date: Tue, 24 Mar 2026 14:49:52 +0800 From: Kairui Song To: Youngjun Park Cc: "Rafael J . Wysocki" , Andrew Morton , Chris Li , Kairui Song , Pavel Machek , Kemeng Shi , Nhat Pham , Baoquan He , Barry Song , Usama Arif , linux-pm@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH v8 2/2] mm/swap: remove redundant swap device reference in alloc/free Message-ID: References: <20260323160822.1409904-1-youngjun.park@lge.com> <20260323160822.1409904-3-youngjun.park@lge.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260323160822.1409904-3-youngjun.park@lge.com> X-Rspamd-Queue-Id: DC2A44000B X-Stat-Signature: 1ach5tspihnw3wkg8tquz5jx3g6oxzjc X-Rspam-User: X-Rspamd-Server: rspam10 X-HE-Tag: 1774334998-246407 X-HE-Meta: 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 +H1KbqZd HfDMZ91li2XQPs8kQKrwR1p3iWwqa82wC/SwXm9zPPHeIZz07oER9K3q+FP9D/lDUz6wgVGSX6JcSctpOdVc7xocWf81n01JZz8hn+r36vpZnbDss8hmFIrrprsJa+tJjL6Ox7s3ySD1l//CpN1OwwrbDe66uqwVqpZyGu0aKIygzFZxaOTT0Ir0IwBqnzSjjCAnvV0SrzRfbO4vHlIrA+GQGQdFTQt4jOGWTQfZCIw/mV56GuNi8fAQ1jpR8zHqc+bGnFkfeZHVhRmoHSIysqPxJSuitwpmh3pL2MyiiB7XWMO8UzE75YO05JQWQtJ8JBLjKBA0ppdVHi4e56KbIeB1j/YopaN7td9s8Cj5+wIM5peOdpBYA6vqhwSdgM1+opr/s7ZJRvveptSWhgzo/3PhIPaiNADFozNZ+2Q4Q4S1/mOfiZXgT+FNXEDCUEdSYf/yn+Yuq4byrVvW28k6X17d54oTrh5UXUBwo Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, Mar 24, 2026 at 01:08:22AM +0800, Youngjun Park wrote: > In the previous commit, uswsusp was modified to pin the swap device > when the swap type is determined, ensuring the device remains valid > throughout the hibernation I/O path. > > Therefore, it is no longer necessary to repeatedly get and put the swap > device reference for each swap slot allocation and free operation. > > For hibernation via the sysfs interface, user-space tasks are frozen > before swap allocation begins, so swapoff cannot race with allocation. > After resume, tasks remain frozen while swap slots are freed, so > additional reference management is not required there either. > > Remove the redundant swap device get/put operations from the > hibernation swap allocation and free paths. > > Also remove the SWP_WRITEOK check before allocation, as the cluster > allocation logic already validates the swap device state. > > Update function comments to document the caller's responsibility for > ensuring swap device stability. > > Signed-off-by: Youngjun Park > --- > mm/swapfile.c | 68 +++++++++++++++++++++++++++------------------------ > 1 file changed, 36 insertions(+), 32 deletions(-) Thanks! Reviewed-by: Kairui Song