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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id E184CC433F5 for ; Tue, 23 Nov 2021 20:00:59 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 318C16B0072; Tue, 23 Nov 2021 15:00:44 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 2C7D76B0074; Tue, 23 Nov 2021 15:00:44 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 1B6B76B0075; Tue, 23 Nov 2021 15:00:44 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0102.hostedemail.com [216.40.44.102]) by kanga.kvack.org (Postfix) with ESMTP id 0B7716B0072 for ; Tue, 23 Nov 2021 15:00:44 -0500 (EST) Received: from smtpin24.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id BFD071802851C for ; Tue, 23 Nov 2021 20:00:33 +0000 (UTC) X-FDA: 78841262346.24.DC494D0 Received: from mail-ed1-f54.google.com (mail-ed1-f54.google.com [209.85.208.54]) by imf09.hostedemail.com (Postfix) with ESMTP id 1BC69300089F for ; Tue, 23 Nov 2021 20:00:30 +0000 (UTC) Received: by mail-ed1-f54.google.com with SMTP id t5so191715edd.0 for ; Tue, 23 Nov 2021 12:00:33 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=OLIu6dOhjs4vufgSpnksyOeHKMHxKx4U/q0KpSn1TzQ=; b=LbeTL942XWZEuXwaE+lfkR5hT8RLhRTix2/UbYTfTJQ7M7lWyzt/ZXwGiumtoCUW+e 1hOIXOn9jK0zUrXfyma9qVp0XHZFTrNoJBwajRiR8XrXu9GWaWtzy2DPRWyeLd2xnX94 oAFICe7pBHzAcZBKtRMbay0jvUEPt1Xh/ZsSTACgntbCA/C3OtsQTxKJ/kPS6+iE4yaa pSwiKRZYOnvtxOAjWom+25QCH6eslPvTTENHLz04dvU7W7lN2v10ffFlugNv87l6jAGh q+KEmX28RFSS8ZS6mZGUyWPBrLVpt8HdoRekmpU8ymomMCcpi7csSIT4Aj0svE7GOOkF aTFw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=OLIu6dOhjs4vufgSpnksyOeHKMHxKx4U/q0KpSn1TzQ=; b=hw23NvH8AuL3rhn9x3pwa9RdIhDcfBce01qk6DxTb/HLmcjbIrhjFI5sTLiTrL7K3X bf0+gLLQYXRVvbiDLrrrvrxkt6KAicuS3jY0BiaNfkCr6AMmN7R8QIhvGnz+DEbDGtAq ntbIy44YbUXXec+g6Kw1SEOyerM9nzs8cUgGvhBOsZ8iiSfvu6HVvqVFx2Jh17R4mH6q QSJBd2pdTFURBK8Qq2PESMjtquLQR9k4F7vcBizWK133d6t/ACpW5TaXMc8NFfmVuUw5 CAc5DrH+csNjUjfslzw5Gv/jQ+Tmb0HznpXnZEZsihba2yjwmxm/eDS+nSbf6W0fLFwZ NP1Q== X-Gm-Message-State: AOAM533mT41h9FYl/XITxLoJO7wCfsSp9Hlm4sDV2AX1VkB07QyUZDIo Fg9k9ZveubZUVY6TyZ3krzJaHI8fZvwiQxZ2wpw= X-Google-Smtp-Source: ABdhPJxGYJqFC7AvC31S9S38mojNSaXY0eQIavmTz6Qa3fAIaf5JamesroypEO91N4hGDq2TSg0wVUgrgR9d0SrR8PU= X-Received: by 2002:a50:a6ca:: with SMTP id f10mr13427258edc.81.1637697631969; Tue, 23 Nov 2021 12:00:31 -0800 (PST) MIME-Version: 1.0 References: <20211123190916.1738458-1-shakeelb@google.com> In-Reply-To: <20211123190916.1738458-1-shakeelb@google.com> From: Yang Shi Date: Tue, 23 Nov 2021 12:00:19 -0800 Message-ID: Subject: Re: [PATCH v2] mm: thp: update split_queue_len correctly To: Shakeel Butt Cc: David Hildenbrand , "Kirill A . Shutemov" , Zi Yan , Matthew Wilcox , Andrew Morton , Linux MM , Linux Kernel Mailing List Content-Type: text/plain; charset="UTF-8" X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 1BC69300089F X-Stat-Signature: gqjyjuf83gnjc59pqntzpjbiqch3km44 Authentication-Results: imf09.hostedemail.com; dkim=pass header.d=gmail.com header.s=20210112 header.b=LbeTL942; dmarc=pass (policy=none) header.from=gmail.com; spf=pass (imf09.hostedemail.com: domain of shy828301@gmail.com designates 209.85.208.54 as permitted sender) smtp.mailfrom=shy828301@gmail.com X-HE-Tag: 1637697630-969629 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 Tue, Nov 23, 2021 at 11:09 AM Shakeel Butt wrote: > > The deferred THPs are split on memory pressure through shrinker > callback and splitting of THP during reclaim can fail for several > reasons like unable to lock the THP, under writeback or unexpected > number of pins on the THP. Such pages are put back on the deferred split > list for consideration later. However kernel does not update the > deferred queue size on putting back the pages whose split was failed. > This patch fixes that. > > Without this patch the split_queue_len can underflow. Shrinker will > always get that there are some THPs to split even if there are not and > waste some cpu to scan the empty list. > > Fixes: 364c1eebe453 ("mm: thp: extract split_queue_* into a struct") > Signed-off-by: Shakeel Butt > --- > Changes since v1: > - updated commit message > - incorporated Yang Shi's suggestion Reviewed-by: Yang Shi > > mm/huge_memory.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/mm/huge_memory.c b/mm/huge_memory.c > index e5483347291c..d393028681e2 100644 > --- a/mm/huge_memory.c > +++ b/mm/huge_memory.c > @@ -2809,7 +2809,7 @@ static unsigned long deferred_split_scan(struct shrinker *shrink, > unsigned long flags; > LIST_HEAD(list), *pos, *next; > struct page *page; > - int split = 0; > + unsigned long split = 0; > > #ifdef CONFIG_MEMCG > if (sc->memcg) > @@ -2847,6 +2847,7 @@ static unsigned long deferred_split_scan(struct shrinker *shrink, > > spin_lock_irqsave(&ds_queue->split_queue_lock, flags); > list_splice_tail(&list, &ds_queue->split_queue); > + ds_queue->split_queue_len -= split; > spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags); > > /* > -- > 2.34.0.rc2.393.gf8c9666880-goog >