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[147.11.105.121]) by smtp.gmail.com with ESMTPSA id ot15-20020a17090b3b4f00b00280070a2613sm12310848pjb.51.2023.12.13.03.35.30 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 13 Dec 2023 03:35:33 -0800 (PST) Date: Wed, 13 Dec 2023 19:35:28 +0800 From: Kevin Hao To: David Hildenbrand Cc: "Rafael J. Wysocki" , linux-mm@kvack.org, Andrea Arcangeli , Andrew Morton , Pavel Machek Subject: Re: [PATCH] mm: ksm: Remove unnecessary try_to_freeze() Message-ID: References: <20231213090906.1070985-1-haokexin@gmail.com> <92046e20-b05e-4710-93f5-4b64d41b86b6@redhat.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="FtmWSM7KJusEBmZv" Content-Disposition: inline In-Reply-To: <92046e20-b05e-4710-93f5-4b64d41b86b6@redhat.com> X-Rspamd-Queue-Id: 68CB214000E X-Rspam-User: X-Rspamd-Server: rspam05 X-Stat-Signature: 94ownganu1tu18yio5o8t5hg9y18jzda X-HE-Tag: 1702467335-509744 X-HE-Meta: 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 G3tHT4u3 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000006, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: --FtmWSM7KJusEBmZv Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Wed, Dec 13, 2023 at 12:28:21PM +0100, David Hildenbrand wrote: > On 13.12.23 12:17, Rafael J. Wysocki wrote: > > On Wed, Dec 13, 2023 at 10:09=E2=80=AFAM Kevin Hao = wrote: > > >=20 > > > A freezable kernel thread can enter frozen state during freezing by > > > either calling try_to_freeze() or using wait_event_freezable() and its > > > variants. However, there is no need to use both methods simultaneousl= y. > >=20 > > The changelog doesn't match the patch IMV. > >=20 >=20 > Staring at the code, I think it makes sense once one spots the existing > "wait_event_freezable()" on the else path. Yes. The change from wait_event_interruptible_timeout() to wait_event_freezable_timeout() led to some confusion. In the else path, the= re is indeed a wait_event_freezable(). The complete code is as follows: static int ksm_scan_thread(void *nothing) { unsigned int sleep_ms; set_freezable(); set_user_nice(current, 5); while (!kthread_should_stop()) { mutex_lock(&ksm_thread_mutex); wait_while_offlining(); if (ksmd_should_run()) ksm_do_scan(ksm_thread_pages_to_scan); mutex_unlock(&ksm_thread_mutex); try_to_freeze(); if (ksmd_should_run()) { sleep_ms =3D READ_ONCE(ksm_thread_sleep_millisecs); wait_event_interruptible_timeout(ksm_iter_wait, sleep_ms !=3D READ_ONCE(ksm_thread_sleep_millisecs), msecs_to_jiffies(sleep_ms)); } else { wait_event_freezable(ksm_thread_wait, ksmd_should_run() || kthread_should_stop()); } } return 0; } Thanks, Kevin --FtmWSM7KJusEBmZv Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEEHc6qFoLCZqgJD98Zk1jtMN6usXEFAmV5lwAACgkQk1jtMN6u sXEbTAf+KLHxHr5lwMtAXb5tAELfKd5oQndPbzlI2gUT1/oyqODegSN1AnEGshQw m8B4oVmGPHQRRvhLPiPmjpV7VowbHdBg+6lDJg6WHPt9upgZbPPP0VKG9g7fWjBF 4tHD08i0QG9fD92FnwsMjpJqJkJXvMJcl8nhobzdhACMvA4r+Zgl6wMxBWYcbSLP lMtedo6SLf7xpaVGIDcT2c8JHuNl87t+gSGQnIUAmeP9KOA6EQO4jPii8Pv/hO/0 vR4OyNneRuFQlLij8hoLoDqFWIR1gHSy/x4/HFJkV95tvaiwDxZXoPleYgw2ID2Z 57RRwv/igJ5enVQoNVLFVTCFPnqw8A== =gln3 -----END PGP SIGNATURE----- --FtmWSM7KJusEBmZv--