From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6619DEB8FA5 for ; Wed, 6 Sep 2023 08:08:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234667AbjIFIIp (ORCPT ); Wed, 6 Sep 2023 04:08:45 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58242 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234687AbjIFIIo (ORCPT ); Wed, 6 Sep 2023 04:08:44 -0400 Received: from out-212.mta1.migadu.com (out-212.mta1.migadu.com [IPv6:2001:41d0:203:375::d4]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4D837CF4 for ; Wed, 6 Sep 2023 01:08:12 -0700 (PDT) Content-Type: text/plain; charset=us-ascii DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1693987681; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=cqhvozPJyOZ2dLvEvaEN6mEFv0YePr1ku/O9UOlrXRU=; b=iIxpJPM73cdK4dsInHamJ3MzzFXV6/nEKenRQiyFE1arzvCbMPiQ0i1ArjNn8v6FVohm9w 2t3LqDkJ3FMfr64vBS6NYjlNxpiE90DNkWPfYyGA1p+/FJ5Mk7IKw7oF4odAO+Fm/cWbv8 /Tr6FEF2JN2NbyvLRsVZssJWtX/TDIQ= Mime-Version: 1.0 Subject: Re: [PATCH v2 07/11] hugetlb: perform vmemmap restoration on a list of pages X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Muchun Song In-Reply-To: <5e091211-9a32-8480-55fb-faff6a0fadef@linux.dev> Date: Wed, 6 Sep 2023 16:07:20 +0800 Cc: Muchun Song , Joao Martins , Oscar Salvador , David Hildenbrand , Miaohe Lin , David Rientjes , Anshuman Khandual , Naoya Horiguchi , Barry Song , Michal Hocko , Matthew Wilcox , Xiongchun Duan , Andrew Morton Content-Transfer-Encoding: quoted-printable Message-Id: <38E2F051-E00B-4104-A616-0EEB2729386F@linux.dev> References: <20230905214412.89152-1-mike.kravetz@oracle.com> <20230905214412.89152-8-mike.kravetz@oracle.com> <5e091211-9a32-8480-55fb-faff6a0fadef@linux.dev> To: Mike Kravetz , Linux-MM , LKML X-Migadu-Flow: FLOW_OUT Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > On Sep 6, 2023, at 15:33, Muchun Song wrote: >=20 >=20 >=20 > On 2023/9/6 05:44, Mike Kravetz wrote: >> When removing hugetlb pages from the pool, we first create a list >> of removed pages and then free those pages back to low level = allocators. >> Part of the 'freeing process' is to restore vmemmap for all base = pages >> if necessary. Pass this list of pages to a new routine >> hugetlb_vmemmap_restore_folios() so that vmemmap restoration can be >> performed in bulk. >>=20 >> Signed-off-by: Mike Kravetz >> --- >> mm/hugetlb.c | 3 +++ >> mm/hugetlb_vmemmap.c | 13 +++++++++++++ >> mm/hugetlb_vmemmap.h | 5 +++++ >> 3 files changed, 21 insertions(+) >>=20 >> diff --git a/mm/hugetlb.c b/mm/hugetlb.c >> index 554be94b07bd..dd2dbc256172 100644 >> --- a/mm/hugetlb.c >> +++ b/mm/hugetlb.c >> @@ -1838,6 +1838,9 @@ static void update_and_free_pages_bulk(struct = hstate *h, struct list_head *list) >> { >> struct folio *folio, *t_folio; >> + /* First restore vmemmap for all pages on list. */ >> + hugetlb_vmemmap_restore_folios(h, list); >> + >> list_for_each_entry_safe(folio, t_folio, list, lru) { >> update_and_free_hugetlb_folio(h, folio, false); >> cond_resched(); >> diff --git a/mm/hugetlb_vmemmap.c b/mm/hugetlb_vmemmap.c >> index ac5577d372fe..79de984919ef 100644 >> --- a/mm/hugetlb_vmemmap.c >> +++ b/mm/hugetlb_vmemmap.c >> @@ -481,6 +481,19 @@ int hugetlb_vmemmap_restore(const struct hstate = *h, struct page *head) >> return ret; >> } >> +/* >> + * This function will attempt to resore vmemmap for a list of = folios. There >> + * is no guarantee that restoration will be successful for all or = any folios. >> + * This is used in bulk operations, and no feedback is given to the = caller. >> + */ >> +void hugetlb_vmemmap_restore_folios(const struct hstate *h, struct = list_head *folio_list) >> +{ >> + struct folio *folio; >> + >> + list_for_each_entry(folio, folio_list, lru) >> + (void)hugetlb_vmemmap_restore(h, &folio->page); >=20 > I am curious about the purpose of "void" here, seems it it not = necessnary, > ritgh? We cound see so many palces where we do not add the void if the = caller > does not care about the return value of the callee. Another question: should we stop restoring vmemmap pages when hugetlb_vmemmap_restore() fails? In which case, I suspect there is no memory probably, there is no need to continue, right? >=20 > Thanks. >> +} >> + >> /* Return true iff a HugeTLB whose vmemmap should and can be = optimized. */ >> static bool vmemmap_should_optimize(const struct hstate *h, const = struct page *head) >> { >> diff --git a/mm/hugetlb_vmemmap.h b/mm/hugetlb_vmemmap.h >> index 036494e040ca..b4ee945dc1d4 100644 >> --- a/mm/hugetlb_vmemmap.h >> +++ b/mm/hugetlb_vmemmap.h >> @@ -12,6 +12,7 @@ >> #ifdef CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP >> int hugetlb_vmemmap_restore(const struct hstate *h, struct page = *head); >> +void hugetlb_vmemmap_restore_folios(const struct hstate *h, struct = list_head *folio_list); >> void hugetlb_vmemmap_optimize(const struct hstate *h, struct page = *head); >> void hugetlb_vmemmap_optimize_folios(struct hstate *h, struct = list_head *folio_list); >> @@ -44,6 +45,10 @@ static inline int hugetlb_vmemmap_restore(const = struct hstate *h, struct page *h >> return 0; >> } >> +static inline void hugetlb_vmemmap_restore_folios(const struct = hstate *h, struct list_head *folio_list) >> +{ >> +} >> + >> static inline void hugetlb_vmemmap_optimize(const struct hstate *h, = struct page *head) >> { >> } >=20