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 X-Spam-Level: X-Spam-Status: No, score=-13.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A8947C433DB for ; Thu, 7 Jan 2021 03:12:22 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 050F12229C for ; Thu, 7 Jan 2021 03:12:21 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 050F12229C Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=bytedance.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 671798D0090; Wed, 6 Jan 2021 22:12:21 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 621876B0297; Wed, 6 Jan 2021 22:12:21 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 50F5C8D0090; Wed, 6 Jan 2021 22:12:21 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0226.hostedemail.com [216.40.44.226]) by kanga.kvack.org (Postfix) with ESMTP id 3BA396B0294 for ; Wed, 6 Jan 2021 22:12:21 -0500 (EST) Received: from smtpin14.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 0C93E180AD802 for ; Thu, 7 Jan 2021 03:12:21 +0000 (UTC) X-FDA: 77677505682.14.cry30_3f10627274e6 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin14.hostedemail.com (Postfix) with ESMTP id E96371822987A for ; Thu, 7 Jan 2021 03:12:20 +0000 (UTC) X-HE-Tag: cry30_3f10627274e6 X-Filterd-Recvd-Size: 4079 Received: from mail-pj1-f49.google.com (mail-pj1-f49.google.com [209.85.216.49]) by imf36.hostedemail.com (Postfix) with ESMTP for ; Thu, 7 Jan 2021 03:12:20 +0000 (UTC) Received: by mail-pj1-f49.google.com with SMTP id u4so1158563pjn.4 for ; Wed, 06 Jan 2021 19:12:20 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bytedance-com.20150623.gappssmtp.com; s=20150623; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=tFaQSU6zAPh4XFUMfv4Im/acDbmbkFA05vZT/8+GY7s=; b=ireGTiKbcsC3M6ko83iv9eDXH6Wr2YSly3Ds/y0S5G++26mBju5yYZ1WKJaHDfFCC9 +jbAKKr2SoqFkQjXUwiUm0AjaqPS6khLSqyJDAWAmQ6QZPG4SLO7uYml8uC0sIJR71/M EKe0j5yNudWGT+qWLzrgs2mdDS3rvlvk4UgIhOWpQSOLuyHnEjNalq7b+EnsheNc+6+j 0K7VQto+e7/jDiLEBwV+X0XGbTU8JEh4FhWefpP6h8wP41AI5n+DwawRPJ9YR1drdQP1 Gj87sAY/O7UnXuULKOF5YnvAxa11BJyeLwwC4TraM/c84aFOF79MRWsKwz8e1JWxxa88 LcPA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=tFaQSU6zAPh4XFUMfv4Im/acDbmbkFA05vZT/8+GY7s=; b=o8BxEWYEMAm3w+klLQTUCGvQxTp/aLqNaqYvm+7mEWEHAQteyLiXwAXOHGR/W6m+Zk C3gKpf/G1oOyYD7oFVNHbJrrXmeLU2uBJHcgUhOTFQJrl2syYBH6Qn8vrkNnWsW6JTnc 78WNUR4u+UXM+TX9qyb66xWSSHmpp2gHSXqvT+QCWY/OfVLObjUyTkHgbu52xT8mKJRo bZvpWRL38Eg6jGnuPNtSdtX/zPTktpKE8dRA1b8qU4Ao8V7KBuuDQMbOaUcff6B61DRZ r4rCReM5lfk9Lsfhmi/2c17jgLYw0vdzSAS2c9gxWpfLAhE36PDgSVfEf8DZwFAjtOLm QM/w== X-Gm-Message-State: AOAM532nwKEcryKdYUKGprBJJxo3RdyUJ2ys6wfgv8vEkLkLZEikqEdM FwAedSwt9RQM8ATO5GUjbptabBHg9VlEpLFXr9QjiQ== X-Google-Smtp-Source: ABdhPJwqyiEy1UwHz4mlEsLelbauSmVFuTl8jJOx4KxXEQjC6QLSOQd15b9MS5kSSgziVXrcoc0a2Ber03b6EI983pE= X-Received: by 2002:a17:902:8503:b029:dc:44f:62d8 with SMTP id bj3-20020a1709028503b02900dc044f62d8mr7387757plb.34.1609989139255; Wed, 06 Jan 2021 19:12:19 -0800 (PST) MIME-Version: 1.0 References: <20210106084739.63318-1-songmuchun@bytedance.com> <20210106084739.63318-5-songmuchun@bytedance.com> <20210106170754.GU13207@dhcp22.suse.cz> In-Reply-To: <20210106170754.GU13207@dhcp22.suse.cz> From: Muchun Song Date: Thu, 7 Jan 2021 11:11:41 +0800 Message-ID: Subject: Re: [External] Re: [PATCH v2 4/6] mm: hugetlb: add return -EAGAIN for dissolve_free_huge_page To: Michal Hocko Cc: Mike Kravetz , Andrew Morton , Naoya Horiguchi , Andi Kleen , Linux Memory Management List , LKML Content-Type: text/plain; charset="UTF-8" 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 Thu, Jan 7, 2021 at 1:07 AM Michal Hocko wrote: > > On Wed 06-01-21 16:47:37, Muchun Song wrote: > > When dissolve_free_huge_page() races with __free_huge_page(), we can > > do a retry. Because the race window is small. > > Is this a bug fix or mere optimization. I have hard time to tell from > the description. It is optimization. Thanks. > > > Signed-off-by: Muchun Song > > --- > > mm/hugetlb.c | 26 +++++++++++++++++++++----- > > 1 file changed, 21 insertions(+), 5 deletions(-) > > > > diff --git a/mm/hugetlb.c b/mm/hugetlb.c > [...] > > @@ -1825,6 +1828,14 @@ int dissolve_free_huge_page(struct page *page) > > } > > out: > > spin_unlock(&hugetlb_lock); > > + > > + /* > > + * If the freeing of the HugeTLB page is put on a work queue, we should > > + * flush the work before retrying. > > + */ > > + if (unlikely(rc == -EAGAIN)) > > + flush_work(&free_hpage_work); > > Is it safe to wait for the work to finish from this context? Yes. It is safe. > > -- > Michal Hocko > SUSE Labs