Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753190AbdHPCt4 (ORCPT ); Tue, 15 Aug 2017 22:49:56 -0400 Received: from mail-oi0-f68.google.com ([209.85.218.68]:34660 "EHLO mail-oi0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752971AbdHPCtz (ORCPT ); Tue, 15 Aug 2017 22:49:55 -0400 MIME-Version: 1.0 In-Reply-To: <20170816021339.GA23451@blaptop> References: <1502704590-3129-1-git-send-email-zhuhui@xiaomi.com> <20170816021339.GA23451@blaptop> From: Hui Zhu Date: Wed, 16 Aug 2017 10:49:14 +0800 Message-ID: Subject: Re: [PATCH v2] zsmalloc: zs_page_migrate: schedule free_work if zspage is ZS_EMPTY To: Minchan Kim Cc: Hui Zhu , "ngupta@vflare.org" , Sergey Senozhatsky , Linux Memory Management List , "linux-kernel@vger.kernel.org" Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3451 Lines: 90 Hi Minchan, 2017-08-16 10:13 GMT+08:00 Minchan Kim : > Hi Hui, > > On Mon, Aug 14, 2017 at 05:56:30PM +0800, Hui Zhu wrote: >> After commit e2846124f9a2 ("zsmalloc: zs_page_migrate: skip unnecessary > > This patch is not merged yet so the hash is invalid. > That means we may fold this patch to [1] in current mmotm. > > [1] zsmalloc-zs_page_migrate-skip-unnecessary-loops-but-not-return-ebusy-if-zspage-is-not-inuse-fix.patch > >> loops but not return -EBUSY if zspage is not inuse") zs_page_migrate >> can handle the ZS_EMPTY zspage. >> >> But I got some false in zs_page_isolate: >> if (get_zspage_inuse(zspage) == 0) { >> spin_unlock(&class->lock); >> return false; >> } > > I also realized we should make zs_page_isolate succeed on empty zspage > because we allow the empty zspage migration from now on. > Could you send a patch for that as well? OK. I will make a patch for that later. Thanks, Hui > >> The page of this zspage was migrated in before. >> >> The reason is commit e2846124f9a2 ("zsmalloc: zs_page_migrate: skip >> unnecessary loops but not return -EBUSY if zspage is not inuse") just >> handle the "page" but not "newpage" then it keep the "newpage" with >> a empty zspage inside system. >> Root cause is zs_page_isolate remove it from ZS_EMPTY list but not >> call zs_page_putback "schedule_work(&pool->free_work);". Because >> zs_page_migrate done the job without "schedule_work(&pool->free_work);" >> >> Make this patch let zs_page_migrate wake up free_work if need. >> >> Fixes: e2846124f9a2 ("zsmalloc: zs_page_migrate: skip unnecessary loops but not return -EBUSY if zspage is not inuse") >> Signed-off-by: Hui Zhu >> --- >> mm/zsmalloc.c | 13 +++++++++++-- >> 1 file changed, 11 insertions(+), 2 deletions(-) >> >> diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c >> index 62457eb..c6cc77c 100644 >> --- a/mm/zsmalloc.c >> +++ b/mm/zsmalloc.c >> @@ -2035,8 +2035,17 @@ int zs_page_migrate(struct address_space *mapping, struct page *newpage, >> * Page migration is done so let's putback isolated zspage to >> * the list if @page is final isolated subpage in the zspage. >> */ >> - if (!is_zspage_isolated(zspage)) >> - putback_zspage(class, zspage); >> + if (!is_zspage_isolated(zspage)) { >> + /* >> + * Page will be freed in following part. But newpage and >> + * zspage will stay in system if zspage is in ZS_EMPTY >> + * list. So call free_work to free it. >> + * The page and class is locked, we cannot free zspage >> + * immediately so let's defer. >> + */ > > How about this? > > /* > * Since we allow empty zspage migration, putback of zspage > * should free empty zspage. Otherwise, it could make a leak > * until upcoming free_work is done, which isn't guaranteed. > */ >> + if (putback_zspage(class, zspage) == ZS_EMPTY) >> + schedule_work(&pool->free_work); >> + } >> >> reset_page(page); >> put_page(page); >> -- >> 1.9.1 >> >> -- >> To unsubscribe, send a message with 'unsubscribe linux-mm' in >> the body to majordomo@kvack.org. For more info on Linux MM, >> see: http://www.linux-mm.org/ . >> Don't email: email@kvack.org