From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg0-f71.google.com (mail-pg0-f71.google.com [74.125.83.71]) by kanga.kvack.org (Postfix) with ESMTP id 1A0B26B025F for ; Mon, 14 Aug 2017 05:20:20 -0400 (EDT) Received: by mail-pg0-f71.google.com with SMTP id 16so126783508pgg.8 for ; Mon, 14 Aug 2017 02:20:20 -0700 (PDT) Received: from lgeamrelo11.lge.com (LGEAMRELO11.lge.com. [156.147.23.51]) by mx.google.com with ESMTP id y12si3868361pgs.202.2017.08.14.02.20.18 for ; Mon, 14 Aug 2017 02:20:19 -0700 (PDT) Date: Mon, 14 Aug 2017 18:20:17 +0900 From: Minchan Kim Subject: Re: [PATCH] zsmalloc: zs_page_migrate: schedule free_work if zspage is ZS_EMPTY Message-ID: <20170814092017.GH26913@bbox> References: <1502692486-27519-1-git-send-email-zhuhui@xiaomi.com> <20170814083105.GC26913@bbox> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org List-ID: To: Hui Zhu Cc: Hui Zhu , "ngupta@vflare.org" , Sergey Senozhatsky , Linux Memory Management List , "linux-kernel@vger.kernel.org" On Mon, Aug 14, 2017 at 05:11:50PM +0800, Hui Zhu wrote: > 2017-08-14 16:31 GMT+08:00 Minchan Kim : > > Hi Hui, > > > > On Mon, Aug 14, 2017 at 02:34:46PM +0800, Hui Zhu wrote: > >> After commit e2846124f9a2 ("zsmalloc: zs_page_migrate: skip unnecessary > >> loops but not return -EBUSY if zspage is not inuse") zs_page_migrate > >> can handle the ZS_EMPTY zspage. > >> > >> But it will affect the free_work free the zspage. That will make this > >> ZS_EMPTY zspage stay in system until another zspage wake up 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 > > > > This patch makes me remind why I didn't try to migrate empty zspage > > as you did e2846124f9a2. I have forgotten it toally. > > > > We cannot guarantee when the freeing of the page happens if we use > > deferred freeing in zs_page_migrate. However, we returns > > MIGRATEPAGE_SUCCESS which is totally lie. > > Without instant freeing the page, it doesn't help the migration > > situation. No? > > > > Sorry I think the reason is I didn't introduce this clear. > After I patch e2846124f9a2. I got some false in zs_page_isolate: > if (get_zspage_inuse(zspage) == 0) { > spin_unlock(&class->lock); > return false; > } > The page of this zspage was migrated in before. > > So I think e2846124f9a2 is OK that MIGRATEPAGE_SUCCESS with the "page". > But 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);" > > That is why I made the new patch. Thanks. Now I got it. Could you resend the patch with such detailed information? < snip > > >> + if (!is_zspage_isolated(zspage)) { > >> + /* > >> + * The page and class is locked, we cannot free zspage > >> + * immediately so let's defer. Please put more words about that why we should calls schedule_work in here. Thanks! > >> + */ > >> + 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 -- 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