On Thu, Feb 8, 2024 at 11:29 AM Johannes Weiner <hannes@xxxxxxxxxxx> wrote: > > On Mon, Feb 05, 2024 at 09:08:05AM +0800, Zhongkun He wrote: > > On Mon, Feb 5, 2024 at 2:46 AM Matthew Wilcox <willy@xxxxxxxxxxxxx> 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.
