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[209.85.220.65]) by mx.google.com with SMTPS id d205sor780482iof.131.2019.03.29.01.56.33 for (Google Transport Security); Fri, 29 Mar 2019 01:56:33 -0700 (PDT) Received-SPF: pass (google.com: domain of laoar.shao@gmail.com designates 209.85.220.65 as permitted sender) client-ip=209.85.220.65; Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b="GU83I7/t"; spf=pass (google.com: domain of laoar.shao@gmail.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=laoar.shao@gmail.com; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=mD76T4dAek37Wg0CPxcHTAlVwwpZbdYRx32N/350cVw=; b=GU83I7/tpRYBL9XgbI1EI+GxRw+gV0pHH9Mzf6o9Y8EOkV6WbXbrN9MaQmL18dWjqE SNsi/zkLXwN72m0UfYclRR82LPhwQruHEZOA9wcUf2Yl1Lk38c6dkStD/9ZbFciQONfP c+Mcex3+6Fh/DR2El6nCzDQvcBnUXZoulmjK2ZRjon2dQysZbUr003vGXh/5yWmLChUU RwiFVBcMfPAauJBJmEz9kyA3DYis6IerQtg/JD4eVteAeJchb7nKylG35HqZEcREi3m5 Jfdw4VvqTb7sd2bv1sDmF1J1XnMXY+l9Q3lDmdt0+hKoQMMYc6nJHS8IAmEPs6YNKTVe JcCg== X-Google-Smtp-Source: APXvYqxlHm5sV8mBsA6ucD/xdolGp/3FxzBgnNEMIXmdME8cQBF5f18wkyJdCm73dxbfO5fVzwAEXPFjdzDnxUf65DU= X-Received: by 2002:a6b:e50d:: with SMTP id y13mr29863307ioc.142.1553849792889; Fri, 29 Mar 2019 01:56:32 -0700 (PDT) MIME-Version: 1.0 References: <1553848599-6124-1-git-send-email-laoar.shao@gmail.com> <60f6a5fd-e4d3-b615-6f41-cc7dd16d183c@suse.cz> In-Reply-To: From: Yafang Shao Date: Fri, 29 Mar 2019 16:55:56 +0800 Message-ID: Subject: Re: [PATCH] mm/compaction: fix missed direct_compaction setting for non-direct compaction To: Vlastimil Babka Cc: Michal Hocko , mgorman@techsingularity.net, Andrew Morton , Linux MM , shaoyafang@didiglobal.com 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 Fri, Mar 29, 2019 at 4:54 PM Vlastimil Babka wrote: > > On 3/29/19 9:48 AM, Yafang Shao wrote: > > On Fri, Mar 29, 2019 at 4:45 PM Vlastimil Babka wrote: > >> > >> On 3/29/19 9:36 AM, Yafang Shao wrote: > >>> direct_compaction is not initialized for kcompactd or manually triggered > >>> compaction (via /proc or /sys). > >> > >> It doesn't need to, this style of initialization does guarantee that any > >> field not explicitly mentioned is initialized to 0/NULL/false... and > >> this pattern is used all over the kernel. > >> > > > > Hmm. > > You mean the gcc will set the local variable to 0 ? > > Not local variable, but fields omitted in this "designated initializers" > scenario. > > > Are there any reference to this behavior ? > > https://gcc.gnu.org/onlinedocs/gcc/Designated-Inits.html > > "Omitted fields are implicitly initialized the same as for objects that > have static storage duration. " > and static objects are implicitly 0 > Got it! Many thanks for your help. Thanks Yafang