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Tsirkin" , David Hildenbrand , Jason Wang , Dave Hansen , Michal Hocko , Liang Li , linux-mm@kvack.org, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org References: <20210106034918.GA1154@open-light-1.localdomain> From: Mike Kravetz Message-ID: <3bfdbe48-5818-7470-4c3b-96e62d387fb4@oracle.com> Date: Thu, 7 Jan 2021 14:04:37 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.1.1 MIME-Version: 1.0 In-Reply-To: <20210106034918.GA1154@open-light-1.localdomain> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9857 signatures=668683 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 mlxlogscore=999 phishscore=0 suspectscore=0 spamscore=0 bulkscore=0 adultscore=0 mlxscore=0 malwarescore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2009150000 definitions=main-2101070125 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9857 signatures=668683 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 adultscore=0 bulkscore=0 spamscore=0 impostorscore=0 phishscore=0 lowpriorityscore=0 suspectscore=0 priorityscore=1501 mlxscore=0 malwarescore=0 clxscore=1015 mlxlogscore=999 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2009150000 definitions=main-2101070125 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: On 1/5/21 7:49 PM, Liang Li wrote: > hugetlb manages its page in hstate's free page list, not in buddy > system, this patch try to make it works for hugetlbfs. It canbe > used for memory overcommit in virtualization and hugetlb pre zero > out. I am not looking closely at the hugetlb changes yet. There seem to be higher level questions about page reporting/etc. Once those are sorted, I will be happy to take a closer look. One quick question below. > --- a/mm/hugetlb.c > +++ b/mm/hugetlb.c > @@ -41,6 +41,7 @@ > #include > #include > #include > +#include "page_reporting.h" > #include "internal.h" > > int hugetlb_max_hstate __read_mostly; > @@ -1028,6 +1029,9 @@ static void enqueue_huge_page(struct hstate *h, struct page *page) > list_move(&page->lru, &h->hugepage_freelists[nid]); > h->free_huge_pages++; > h->free_huge_pages_node[nid]++; > + if (hugepage_reported(page)) > + __ClearPageReported(page); > + hugepage_reporting_notify_free(h->order); > } > > static struct page *dequeue_huge_page_node_exact(struct hstate *h, int nid) > @@ -5531,6 +5535,21 @@ follow_huge_pgd(struct mm_struct *mm, unsigned long address, pgd_t *pgd, int fla > return pte_page(*(pte_t *)pgd) + ((address & ~PGDIR_MASK) >> PAGE_SHIFT); > } > > +void isolate_free_huge_page(struct page *page, struct hstate *h, int nid) > +{ > + VM_BUG_ON_PAGE(!PageHead(page), page); > + > + list_move(&page->lru, &h->hugepage_activelist); > + set_page_refcounted(page); > +} > + > +void putback_isolate_huge_page(struct hstate *h, struct page *page) > +{ > + int nid = page_to_nid(page); > + > + list_move(&page->lru, &h->hugepage_freelists[nid]); > +} The above routines move pages between the free and active lists without any update to free page counts. How does that work? Will the number of entries on the free list get out of sync with the free_huge_pages counters? -- Mike Kravetz