From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Zijlstra Subject: Re: [RFC PATCH v9 03/13] mm: Add support for eXclusive Page Frame Ownership (XPFO) Date: Thu, 4 Apr 2019 09:21:52 +0200 Message-ID: <20190404072152.GN4038@hirez.programming.kicks-ass.net> References: Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: Khalid Aziz Cc: catalin.marinas-5wv7dgnIgG8@public.gmane.org, will.deacon-5wv7dgnIgG8@public.gmane.org, steven.sistare-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org, hch-jcswGhMUV9g@public.gmane.org, tycho-E0fblnxP3wo@public.gmane.org, ak-VuQAYsv1563Yd54FQh9/CA@public.gmane.org, aneesh.kumar-tEXmvtCZX7AybS5Ee8rs3A@public.gmane.org, jmorris-gx6/JNMH7DfYtjvyW6yDsg@public.gmane.org, rientjes-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org, anthony.yznaga-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org, riel-ebMLmSuQjDVBDgjK7y7TUQ@public.gmane.org, npiggin-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org, rppt-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org, luto-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, tglx-hfZtesqFncYOwBW4kG4KsQ@public.gmane.org, gregkh-hQyY1W1yCW8ekmWlsbkhG0B+6BGkLq7r@public.gmane.org, rdunlap-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, jrdr.linux-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org, jkosina-AlSwsSmVLrQ@public.gmane.org, joe-6d6DIl74uiNBDgjK7y7TUQ@public.gmane.org, arunks-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org, akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org, dwmw-vV1OtcyAfmbQXOPxS62xeg@public.gmane.org, mark.rutland-5wv7dgnIgG8@public.gmane.org, linux-doc-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, keith.busch-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org, joao.m.martins-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org, hpa-YMNOUZJC4hwAvxtiuMwx3w@public.gmane.org, brgl-ARrdPY/1zhM@public.gmane.org, konrad.wilk-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org, jsteckli-ebkRAfMGSJGzQB+pC5nmwQ@public.gmane.org, jroedel-l3A5Bk7waGM@public.gmane.org, keescook-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org, zhangshaokun-C8/M+/jPZTeaMJb+Lgu22Q@public.gmane.org, boris.ostrovsky-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org, chris.hyser-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, Khalid Aziz List-Id: iommu@lists.linux-foundation.org On Wed, Apr 03, 2019 at 11:34:04AM -0600, Khalid Aziz wrote: > diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h > index 2c471a2c43fa..d17d33f36a01 100644 > --- a/include/linux/mm_types.h > +++ b/include/linux/mm_types.h > @@ -204,6 +204,14 @@ struct page { > #ifdef LAST_CPUPID_NOT_IN_PAGE_FLAGS > int _last_cpupid; > #endif > + > +#ifdef CONFIG_XPFO > + /* Counts the number of times this page has been kmapped. */ > + atomic_t xpfo_mapcount; > + > + /* Serialize kmap/kunmap of this page */ > + spinlock_t xpfo_lock; NAK, see ALLOC_SPLIT_PTLOCKS spinlock_t can be _huge_ (CONFIG_PROVE_LOCKING=y), also are you _really_ sure you want spinlock_t and not raw_spinlock_t ? For CONFIG_PREEMPT_FULL spinlock_t turns into a rtmutex. > +#endif Growing the page-frame by 8 bytes (in the good case) is really sad, that's a _lot_ of memory. > } _struct_page_alignment;