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charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 4AED440005 X-Stat-Signature: mmxkst9wx5s1ifuebkqrtxjjs8fdun43 X-Rspam-User: X-HE-Tag: 1707413969-436826 X-HE-Meta: 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 uzB+2bs/ BIITEdFo2rd6J4RzexfGeq6cMTsAjz0+/aY6sLdkJPBarE6VHq2NCHV/0Gqiwb1v8eS/iYCt2k06r+Z23TvQZgLD7DLZUdqcTOdmbEQqAn2YtKhhAhnMBpyR7wDi3Kf7gSHWmlZ4CM6v0rMG5dkfk8bXmqtYb/wuit85KQNCVyeFQiik/6GOQf3z9ecm/R+osyuxNKUX4SEuntRvyjURvHulNI8pJKXMyMY3yb2a8Dedi4eRzPTkIR05wD9V55XQo4BXsmKpYTH3wHrUMQbB4um8MJuvZeajQBcW5L4dOupCAIp2N3cAQ3Gl5CEbDaihNjvRuuT1uev1byogbq8ZkHUODXaL7lAzv3unR 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 Thu, Feb 8, 2024 at 11:29=E2=80=AFAM Johannes Weiner wrote: > > On Mon, Feb 05, 2024 at 09:08:05AM +0800, Zhongkun He wrote: > > On Mon, Feb 5, 2024 at 2:46=E2=80=AFAM Matthew Wilcox wrote: > > > > > > On Sun, Feb 04, 2024 at 08:54:04PM +0800, Zhongkun He wrote: > > > > There is no need to use spinlock in this section, so > > > > remove it. > > > > > > I don't know this code at all, but the idiom is (relatively) common. > > > It waits until anybody _currently_ holding the lock has released it. > > > > > > That would, eg, make it safe to free the 'pool' memory. > > > > > > > - spin_lock(&pool->lock); > > > > - spin_unlock(&pool->lock); > > > > > > > no, please see the commit 'e774a7bc7f0adb'. > > > > spin_lock(&pool->lock); > > - if (!list_empty(&page->lru)) > > - list_del_init(&page->lru); > > spin_unlock(&pool->lock); > > > > The original purpose of this lock was to protect page->lru, > > which was removed now, so the spinlock is unnecessary. > > But pool->lock protects other stuff too? This doesn't rule out that > there is some other ordering dependency on cycling the lock before > freeing the entry. The person who would know best is the maintainer of > this code, Vitaly. Let's CC him. Thank you for your reply and look forward to hearing from Vitaly.