From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mike Kravetz Subject: Re: [PATCH v11 6/9] hugetlb_cgroup: support noreserve mappings Date: Thu, 6 Feb 2020 14:31:46 -0800 Message-ID: <6cc406e7-757f-4922-ffc0-681df3ee0d18@oracle.com> References: <20200203232248.104733-1-almasrymina@google.com> <20200203232248.104733-6-almasrymina@google.com> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=subject : to : cc : references : from : message-id : date : mime-version : in-reply-to : content-type : content-transfer-encoding; s=corp-2020-01-29; bh=1dCQzBF1Cy1VWMoh0IXhksIqAR1fyX3kpp5QSoJp0Fw=; b=cqVmZRJOQqRb+8a78dIoQFixTd3UhMeWOw931Ihmokotg1vASd711h9Hh0WWZtQijSvJ VjLFglBkrlQGbk+MA/xFbq8dH/eENq/+7+SaSI6GaQgwsJ0pDQnWOFiz4p0SuMlieQ5V UHpxaglv8zW7f7Kgj2d+tmpgK0kkqI5RfO8AJbokVnZi5GEifH3vFK2T5tW7HMJm+p17 LaAFCjGCW/5CJ45xqqdSVNNe6CcbTmOAvRnsW732CUbxTPFWNp3ZUq+ZruMW4OoisB1o Go5dXCXvufxN4N9Igk+ULW4Mghu5KdGiZ3U9oGbXquaPuf7ihzLs8oFf27tbrskOAras Dw== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=subject : to : cc : references : from : message-id : date : mime-version : in-reply-to : content-type : content-transfer-encoding; s=corp-2019-08-05; bh=1dCQzBF1Cy1VWMoh0IXhksIqAR1fyX3kpp5QSoJp0Fw=; b=QEOGG3DrrUHxV3xUm43ars+LaIjQMuvppX08nVNAFGDn9SxuhI3AbfQYuJpAefKfFkN9 Go+HaUhJwksZqQqansJcaPnpJFEOwBGP+ssuibZKLUK1hJhYDpL7aDNohKtvbwB9TP4X 0v1p29PmGJ/04u36yGb9+gw9dOulEcsvSbcDmV7LMbrFr0AeOJ5ADXVzfZbRDXMFfJhd rr0uAz+wxk0b83NFA9V4QSRhqz6QZBtABUYYN6UxhTJ3LTaDb+kXBAb8BybFx8c1m7Wc wrtH4yI103ik2kkRuU5A6qoUAG9OWSkLKXJoNSSHpU6BIpUaHFulOyYOhJGazbuuzeJ7 ig== In-Reply-To: <20200203232248.104733-6-almasrymina-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org> Content-Language: en-US Sender: cgroups-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: Content-Type: text/plain; charset="us-ascii" To: Mina Almasry Cc: shuah-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, rientjes-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org, shakeelb-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org, gthelen-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org, akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org, linux-kselftest-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org On 2/3/20 3:22 PM, Mina Almasry wrote: > Support MAP_NORESERVE accounting as part of the new counter. > > For each hugepage allocation, at allocation time we check if there is > a reservation for this allocation or not. If there is a reservation for > this allocation, then this allocation was charged at reservation time, > and we don't re-account it. If there is no reserevation for this > allocation, we charge the appropriate hugetlb_cgroup. > > The hugetlb_cgroup to uncharge for this allocation is stored in > page[3].private. We use new APIs added in an earlier patch to set this > pointer. Ah! That reminded me to look at the migration code. Turns out that none of the existing cgroup information (page[2]) is being migrated today. That is a bug. :( I'll confirm and fix in a patch separate from this series. We will need to make sure that new information added by this series in page[3] is also migrated. That would be in an earlier patch where the use of the field is introduced. > > Signed-off-by: Mina Almasry > > --- > > Changes in v10: > - Refactored deferred_reserve check. > > --- > mm/hugetlb.c | 28 +++++++++++++++++++++++++++- > 1 file changed, 27 insertions(+), 1 deletion(-) > > diff --git a/mm/hugetlb.c b/mm/hugetlb.c > index 33818ccaf7e89..ec0b55ea1506e 100644 > --- a/mm/hugetlb.c > +++ b/mm/hugetlb.c > @@ -1339,6 +1339,9 @@ static void __free_huge_page(struct page *page) > clear_page_huge_active(page); > hugetlb_cgroup_uncharge_page(hstate_index(h), pages_per_huge_page(h), > page, false); > + hugetlb_cgroup_uncharge_page(hstate_index(h), pages_per_huge_page(h), > + page, true); > + When looking at the code without change markings, the two above lines look so similar my first thought is there must be a mistake. A suggestion for better code readability: - hugetlb_cgroup_uncharge_page could just take "struct hstate *h" and get both hstate_index(h) and pages_per_huge_page(h). - Perhaps make hugetlb_cgroup_uncharge_page and hugetlb_cgroup_uncharge_page_rsvd be wrappers around a common routine. Then the above would look like: hugetlb_cgroup_uncharge_page(h, page); hugetlb_cgroup_uncharge_page_rsvd(h, page); > if (restore_reserve) > h->resv_huge_pages++; > > @@ -2172,6 +2175,7 @@ struct page *alloc_huge_page(struct vm_area_struct *vma, > long gbl_chg; > int ret, idx; > struct hugetlb_cgroup *h_cg; > + bool deferred_reserve; > > idx = hstate_index(h); > /* > @@ -2209,10 +2213,20 @@ struct page *alloc_huge_page(struct vm_area_struct *vma, > gbl_chg = 1; > } > > + /* If this allocation is not consuming a reservation, charge it now. > + */ > + deferred_reserve = map_chg || avoid_reserve || !vma_resv_map(vma); > + if (deferred_reserve) { > + ret = hugetlb_cgroup_charge_cgroup(idx, pages_per_huge_page(h), > + &h_cg, true); > + if (ret) > + goto out_subpool_put; > + } > + > ret = hugetlb_cgroup_charge_cgroup(idx, pages_per_huge_page(h), &h_cg, > false); Hmmm? I'm starting to like the wrapper idea more as a way to help with readability of the bool rsvd argument. hugetlb_cgroup_charge_cgroup_rsvd() hugetlb_cgroup_charge_cgroup() At least to me it makes it easier to read. -- Mike Kravetz > if (ret) > - goto out_subpool_put; > + goto out_uncharge_cgroup_reservation; > > spin_lock(&hugetlb_lock); > /* > @@ -2236,6 +2250,14 @@ struct page *alloc_huge_page(struct vm_area_struct *vma, > } > hugetlb_cgroup_commit_charge(idx, pages_per_huge_page(h), h_cg, page, > false); > + /* If allocation is not consuming a reservation, also store the > + * hugetlb_cgroup pointer on the page. > + */ > + if (deferred_reserve) { > + hugetlb_cgroup_commit_charge(idx, pages_per_huge_page(h), h_cg, > + page, true); > + } > + > spin_unlock(&hugetlb_lock); > > set_page_private(page, (unsigned long)spool); > @@ -2261,6 +2283,10 @@ struct page *alloc_huge_page(struct vm_area_struct *vma, > out_uncharge_cgroup: > hugetlb_cgroup_uncharge_cgroup(idx, pages_per_huge_page(h), h_cg, > false); > +out_uncharge_cgroup_reservation: > + if (deferred_reserve) > + hugetlb_cgroup_uncharge_cgroup(idx, pages_per_huge_page(h), > + h_cg, true); > out_subpool_put: > if (map_chg || avoid_reserve) > hugepage_subpool_put_pages(spool, 1); > -- > 2.25.0.341.g760bfbb309-goog