From: Matthew Wilcox <firstname.lastname@example.org> To: Michal Hocko <email@example.com>, Andrew Morton <firstname.lastname@example.org>, Mike Kravetz <email@example.com>, Waiman Long <firstname.lastname@example.org>, email@example.com, firstname.lastname@example.org, email@example.com Subject: Re: [PATCH v2] mm/hugetlb: defer free_huge_page() to a workqueue Date: Mon, 16 Dec 2019 09:18:38 -0800 [thread overview] Message-ID: <20191216171838.GA32169@bombadil.infradead.org> (raw) In-Reply-To: <20191216161748.tgi2oictlfqy6azi@linux-p48b> On Mon, Dec 16, 2019 at 08:17:48AM -0800, Davidlohr Bueso wrote: > On Mon, 16 Dec 2019, Michal Hocko wrote: > > I am afraid that work_struct is too large to be stuffed into the struct > > page array (because of the lockdep part). > > Yeah, this needs to be done without touching struct page. > > Which is why I had done the stack allocated way in this patch, but we > cannot wait for it to complete in irq, so that's out the window. Andi > had suggested percpu allocated work items, but having played with the > idea over the weekend, I don't see how we can prevent another page being > freed on the same cpu before previous work on the same cpu is complete > (cpu0 wants to free pageA, schedules the work, in the mean time cpu0 > wants to free pageB and workerfn for pageA still hasn't been called). Why is it that we can call functions after-an-RCU-period-has-elapsed time, at returning-to-userspace time and after-exiting-hardirq-handler time easily, but the mechanism for calling a function after-we've-finished-handling-softirqs is so bloody hard to use? That's surely the major problem we need to fix.
next prev parent reply other threads:[~2019-12-16 17:18 UTC|newest] Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-12-11 19:46 [PATCH v2] hugetlbfs: Disable softIRQ when taking hugetlb_lock Waiman Long 2019-12-11 22:04 ` Mike Kravetz 2019-12-11 22:19 ` Waiman Long 2019-12-12 1:11 ` Mike Kravetz 2019-12-12 6:06 ` Davidlohr Bueso 2019-12-12 6:30 ` Davidlohr Bueso 2019-12-12 19:04 ` [PATCH v2] mm/hugetlb: defer free_huge_page() to a workqueue Davidlohr Bueso 2019-12-12 19:22 ` Mike Kravetz 2019-12-12 19:36 ` Davidlohr Bueso 2019-12-12 20:52 ` Waiman Long 2019-12-12 21:04 ` Waiman Long 2019-12-16 13:26 ` Michal Hocko 2019-12-16 15:38 ` Waiman Long 2019-12-16 18:44 ` Waiman Long 2019-12-17 9:00 ` Michal Hocko 2019-12-17 18:05 ` Mike Kravetz 2019-12-18 12:18 ` hugetlbfs testing coverage (was: Re: [PATCH v2] mm/hugetlb: defer free_huge_page() to a workqueue) Michal Hocko 2019-12-12 21:01 ` [PATCH v2] mm/hugetlb: defer free_huge_page() to a workqueue Waiman Long 2019-12-16 13:37 ` Michal Hocko 2019-12-16 16:17 ` Waiman Long 2019-12-16 16:17 ` Davidlohr Bueso 2019-12-16 17:18 ` Matthew Wilcox [this message] 2019-12-16 19:08 ` Mike Kravetz 2019-12-16 19:13 ` Waiman Long 2019-12-12 21:32 ` [PATCH v2] hugetlbfs: Disable softIRQ when taking hugetlb_lock Andi Kleen 2019-12-12 22:42 ` Davidlohr Bueso 2019-12-11 23:05 ` Andi Kleen
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