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[198.145.29.99]) by mx.google.com with ESMTPS id c22si12194133pfr.15.2019.05.11.16.28.58 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sat, 11 May 2019 16:28:58 -0700 (PDT) Received-SPF: pass (google.com: domain of akpm@linux-foundation.org designates 198.145.29.99 as permitted sender) client-ip=198.145.29.99; Authentication-Results: mx.google.com; dkim=pass header.i=@kernel.org header.s=default header.b=nU6413kV; spf=pass (google.com: domain of akpm@linux-foundation.org designates 198.145.29.99 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org Received: from localhost.localdomain (c-73-223-200-170.hsd1.ca.comcast.net [73.223.200.170]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id E07EA2183F; Sat, 11 May 2019 23:28:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1557617338; bh=BHuLhxI5aHGVG83YqK2/hCHQq9kJO+FuJp6SI28BFfI=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=nU6413kVDb+PIGWHElsfQ6tapvlj2bCz/1bmMGpNgUPeXxkuwKNe3Dy0uTFp1NVY8 oCufa71IzIzaWeO/VIMqQoTq+iMdsqzx/TsBpN8ie3xb6RkIk7GGM5lGedl+Hb2ar0 7aa1ZW3Ce8KqrZFOGYDQ5AU7/0gQmNKz5IGJ7VEw= Date: Sat, 11 May 2019 16:28:57 -0700 From: Andrew Morton To: Michal Hocko Cc: Yafang Shao , jack@suse.cz, linux-mm@kvack.org, shaoyafang@didiglobal.com Subject: Re: [PATCH] mm/page-writeback: introduce tracepoint for wait_on_page_writeback Message-Id: <20190511162857.12e08e792b32d9cff1fb630a@linux-foundation.org> In-Reply-To: <20190428210538.GB956@dhcp22.suse.cz> References: <1556274402-19018-1-git-send-email-laoar.shao@gmail.com> <20190426112542.bf1cd9fe8e9ed7a659642643@linux-foundation.org> <20190428210538.GB956@dhcp22.suse.cz> X-Mailer: Sylpheed 3.5.1 (GTK+ 2.24.31; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit 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 Sun, 28 Apr 2019 23:05:38 +0200 Michal Hocko wrote: > On Fri 26-04-19 11:25:42, Andrew Morton wrote: > > On Fri, 26 Apr 2019 18:26:42 +0800 Yafang Shao wrote: > [...] > > > +/* > > > + * Wait for a page to complete writeback > > > + */ > > > +void wait_on_page_writeback(struct page *page) > > > +{ > > > + if (PageWriteback(page)) { > > > + trace_wait_on_page_writeback(page, page_mapping(page)); > > > + wait_on_page_bit(page, PG_writeback); > > > + } > > > +} > > > +EXPORT_SYMBOL_GPL(wait_on_page_writeback); > > > > But this is a stealth change to the wait_on_page_writeback() licensing. > > Why do we have to put that out of line in the first place? Seems like a good thing to do from a size and icache-footprint POV. wait_on_page_writeback() has a ton of callsites and the allmodconfig out-of-line version is around 600 bytes of code (gack). > Btw. wait_on_page_bit is EXPORT_SYMBOL... OK, I'll leave wait_on_page_writeback() as EXPROT_SYMBOL().