From patchwork Mon Jun 29 23:45:07 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Dave Hansen X-Patchwork-Id: 11632859 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id F0B496C1 for ; Mon, 29 Jun 2020 23:48:38 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id BAB0120781 for ; Mon, 29 Jun 2020 23:48:38 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org BAB0120781 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.intel.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id CD56E8D001A; Mon, 29 Jun 2020 19:48:37 -0400 (EDT) Delivered-To: linux-mm-outgoing@kvack.org Received: by kanga.kvack.org (Postfix, from userid 40) id C87A36B008C; Mon, 29 Jun 2020 19:48:37 -0400 (EDT) X-Original-To: int-list-linux-mm@kvack.org X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id BC4148D001A; Mon, 29 Jun 2020 19:48:37 -0400 (EDT) X-Original-To: linux-mm@kvack.org X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0163.hostedemail.com [216.40.44.163]) by kanga.kvack.org (Postfix) with ESMTP id A6E916B0089 for ; Mon, 29 Jun 2020 19:48:37 -0400 (EDT) Received: from smtpin14.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id 719FD181AC9C6 for ; Mon, 29 Jun 2020 23:48:37 +0000 (UTC) X-FDA: 76983891474.14.rail35_0303ec526e73 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin14.hostedemail.com (Postfix) with ESMTP id 4446318229818 for ; Mon, 29 Jun 2020 23:48:37 +0000 (UTC) X-Spam-Summary: 1,0,0,,d41d8cd98f00b204,dave.hansen@linux.intel.com,,RULES_HIT:30012:30045:30054:30064:30070:30090,0,RBL:134.134.136.20:@linux.intel.com:.lbl8.mailshell.net-64.95.201.95 62.18.0.100;04yfrgxgg3cb7qkauefhtns1cm9efycxfzmkqgw5jecfpeu8fmwteeppdzrkghx.mzgt73ndtmnoch71byo66dj5eunbeh64z8aq53reyppjunfhok56z1qijta5fkr.4-lbl8.mailshell.net-223.238.255.100,CacheIP:none,Bayesian:0.5,0.5,0.5,Netcheck:none,DomainCache:0,MSF:not bulk,SPF:fn,MSBL:0,DNSBL:none,Custom_rules:0:0:0,LFtime:62,LUA_SUMMARY:none X-HE-Tag: rail35_0303ec526e73 X-Filterd-Recvd-Size: 9480 Received: from mga02.intel.com (mga02.intel.com [134.134.136.20]) by imf04.hostedemail.com (Postfix) with ESMTP for ; Mon, 29 Jun 2020 23:48:36 +0000 (UTC) IronPort-SDR: sEAGDthXdJ0Op4zFpiqyRNV8IND01wJsYZOq1dMbsMjUDNnc2MYVMlVhJoIQxO7ezs/siDtoLs g/wDTueDaI4g== X-IronPort-AV: E=McAfee;i="6000,8403,9666"; a="134402965" X-IronPort-AV: E=Sophos;i="5.75,296,1589266800"; d="scan'208";a="134402965" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga007.jf.intel.com ([10.7.209.58]) by orsmga101.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 29 Jun 2020 16:48:31 -0700 IronPort-SDR: 3DjoyN++8LiPSXa9PvxNGIDMIgxrTeGxgSGD58gJlLuHdbVM4qG3L9wV8nfdlyI36qJvEFosLj aa/JJxnxt+AA== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.75,296,1589266800"; d="scan'208";a="320182264" Received: from viggo.jf.intel.com (HELO localhost.localdomain) ([10.54.77.144]) by orsmga007.jf.intel.com with ESMTP; 29 Jun 2020 16:48:31 -0700 Subject: [RFC][PATCH 2/8] mm/migrate: Defer allocating new page until needed To: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org,Dave Hansen ,kbusch@kernel.org,yang.shi@linux.alibaba.com,rientjes@google.com,ying.huang@intel.com,dan.j.williams@intel.com From: Dave Hansen Date: Mon, 29 Jun 2020 16:45:07 -0700 References: <20200629234503.749E5340@viggo.jf.intel.com> In-Reply-To: <20200629234503.749E5340@viggo.jf.intel.com> Message-Id: <20200629234507.CA0FDE19@viggo.jf.intel.com> X-Rspamd-Queue-Id: 4446318229818 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam03 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: From: Keith Busch Migrating pages had been allocating the new page before it was actually needed. Subsequent operations may still fail, which would have to handle cleaning up the newly allocated page when it was never used. Defer allocating the page until we are actually ready to make use of it, after locking the original page. This simplifies error handling, but should not have any functional change in behavior. This is just refactoring page migration so the main part can more easily be reused by other code. #Signed-off-by: Keith Busch Signed-off-by: Dave Hansen Cc: Keith Busch Cc: Yang Shi Cc: David Rientjes Cc: Huang Ying Cc: Dan Williams --- b/mm/migrate.c | 148 ++++++++++++++++++++++++++++----------------------------- 1 file changed, 75 insertions(+), 73 deletions(-) diff -puN mm/migrate.c~0007-mm-migrate-Defer-allocating-new-page-until-needed mm/migrate.c --- a/mm/migrate.c~0007-mm-migrate-Defer-allocating-new-page-until-needed 2020-06-29 16:34:37.896312607 -0700 +++ b/mm/migrate.c 2020-06-29 16:34:37.900312607 -0700 @@ -1014,56 +1014,17 @@ out: return rc; } -static int __unmap_and_move(struct page *page, struct page *newpage, - int force, enum migrate_mode mode) +static int __unmap_and_move(new_page_t get_new_page, + free_page_t put_new_page, + unsigned long private, struct page *page, + enum migrate_mode mode, + enum migrate_reason reason) { int rc = -EAGAIN; int page_was_mapped = 0; struct anon_vma *anon_vma = NULL; bool is_lru = !__PageMovable(page); - - if (!trylock_page(page)) { - if (!force || mode == MIGRATE_ASYNC) - goto out; - - /* - * It's not safe for direct compaction to call lock_page. - * For example, during page readahead pages are added locked - * to the LRU. Later, when the IO completes the pages are - * marked uptodate and unlocked. However, the queueing - * could be merging multiple pages for one bio (e.g. - * mpage_readpages). If an allocation happens for the - * second or third page, the process can end up locking - * the same page twice and deadlocking. Rather than - * trying to be clever about what pages can be locked, - * avoid the use of lock_page for direct compaction - * altogether. - */ - if (current->flags & PF_MEMALLOC) - goto out; - - lock_page(page); - } - - if (PageWriteback(page)) { - /* - * Only in the case of a full synchronous migration is it - * necessary to wait for PageWriteback. In the async case, - * the retry loop is too short and in the sync-light case, - * the overhead of stalling is too much - */ - switch (mode) { - case MIGRATE_SYNC: - case MIGRATE_SYNC_NO_COPY: - break; - default: - rc = -EBUSY; - goto out_unlock; - } - if (!force) - goto out_unlock; - wait_on_page_writeback(page); - } + struct page *newpage; /* * By try_to_unmap(), page->mapcount goes down to 0 here. In this case, @@ -1082,6 +1043,12 @@ static int __unmap_and_move(struct page if (PageAnon(page) && !PageKsm(page)) anon_vma = page_get_anon_vma(page); + newpage = get_new_page(page, private); + if (!newpage) { + rc = -ENOMEM; + goto out; + } + /* * Block others from accessing the new page when we get around to * establishing additional references. We are usually the only one @@ -1091,11 +1058,11 @@ static int __unmap_and_move(struct page * This is much like races on refcount of oldpage: just don't BUG(). */ if (unlikely(!trylock_page(newpage))) - goto out_unlock; + goto out_put; if (unlikely(!is_lru)) { rc = move_to_new_page(newpage, page, mode); - goto out_unlock_both; + goto out_unlock; } /* @@ -1114,7 +1081,7 @@ static int __unmap_and_move(struct page VM_BUG_ON_PAGE(PageAnon(page), page); if (page_has_private(page)) { try_to_free_buffers(page); - goto out_unlock_both; + goto out_unlock; } } else if (page_mapped(page)) { /* Establish migration ptes */ @@ -1131,15 +1098,9 @@ static int __unmap_and_move(struct page if (page_was_mapped) remove_migration_ptes(page, rc == MIGRATEPAGE_SUCCESS ? newpage : page, false); - -out_unlock_both: - unlock_page(newpage); out_unlock: - /* Drop an anon_vma reference if we took one */ - if (anon_vma) - put_anon_vma(anon_vma); - unlock_page(page); -out: + unlock_page(newpage); +out_put: /* * If migration is successful, decrease refcount of the newpage * which will not free the page because new page owner increased @@ -1150,12 +1111,20 @@ out: * state. */ if (rc == MIGRATEPAGE_SUCCESS) { + set_page_owner_migrate_reason(newpage, reason); if (unlikely(!is_lru)) put_page(newpage); else putback_lru_page(newpage); + } else if (put_new_page) { + put_new_page(newpage, private); + } else { + put_page(newpage); } - +out: + /* Drop an anon_vma reference if we took one */ + if (anon_vma) + put_anon_vma(anon_vma); return rc; } @@ -1203,8 +1172,7 @@ static ICE_noinline int unmap_and_move(n int force, enum migrate_mode mode, enum migrate_reason reason) { - int rc = MIGRATEPAGE_SUCCESS; - struct page *newpage = NULL; + int rc = -EAGAIN; if (!thp_migration_supported() && PageTransHuge(page)) return -ENOMEM; @@ -1219,17 +1187,57 @@ static ICE_noinline int unmap_and_move(n __ClearPageIsolated(page); unlock_page(page); } + rc = MIGRATEPAGE_SUCCESS; goto out; } - newpage = get_new_page(page, private); - if (!newpage) - return -ENOMEM; + if (!trylock_page(page)) { + if (!force || mode == MIGRATE_ASYNC) + return rc; - rc = __unmap_and_move(page, newpage, force, mode); - if (rc == MIGRATEPAGE_SUCCESS) - set_page_owner_migrate_reason(newpage, reason); + /* + * It's not safe for direct compaction to call lock_page. + * For example, during page readahead pages are added locked + * to the LRU. Later, when the IO completes the pages are + * marked uptodate and unlocked. However, the queueing + * could be merging multiple pages for one bio (e.g. + * mpage_readpages). If an allocation happens for the + * second or third page, the process can end up locking + * the same page twice and deadlocking. Rather than + * trying to be clever about what pages can be locked, + * avoid the use of lock_page for direct compaction + * altogether. + */ + if (current->flags & PF_MEMALLOC) + return rc; + + lock_page(page); + } + + if (PageWriteback(page)) { + /* + * Only in the case of a full synchronous migration is it + * necessary to wait for PageWriteback. In the async case, + * the retry loop is too short and in the sync-light case, + * the overhead of stalling is too much + */ + switch (mode) { + case MIGRATE_SYNC: + case MIGRATE_SYNC_NO_COPY: + break; + default: + rc = -EBUSY; + goto out_unlock; + } + if (!force) + goto out_unlock; + wait_on_page_writeback(page); + } + rc = __unmap_and_move(get_new_page, put_new_page, private, + page, mode, reason); +out_unlock: + unlock_page(page); out: if (rc != -EAGAIN) { /* @@ -1269,9 +1277,8 @@ out: if (rc != -EAGAIN) { if (likely(!__PageMovable(page))) { putback_lru_page(page); - goto put_new; + goto done; } - lock_page(page); if (PageMovable(page)) putback_movable_page(page); @@ -1280,13 +1287,8 @@ out: unlock_page(page); put_page(page); } -put_new: - if (put_new_page) - put_new_page(newpage, private); - else - put_page(newpage); } - +done: return rc; }