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d=pankajraghav.com; s=MBO0001; t=1715168394; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=W8b5b6l3GLCsDlk5O+ejhQUOklplNdWM3AwYuWOI24c=; b=JzBIM3HhX422tEgKrZjkDJsc26SpEUMYwBHDAqX7Kfq+NZTVCy4SI7U9rrUMzHOttYsWq3 eFRQNzWLuKFRE3k8cq/gkjEO9wbr2EnCBNf2L5luPvZFJgot1pDngkSbmD+S13TVCgtkWm bdkTv9WMLn4147PK7nL+qNltl1D9hDx6C2duc8QvhUccVbWSFtvbMJ2FqD58XwFR3RsO2J 8OI1utieoGx5XklFcqCEqaWXmX90f8YJyGS6WWZI35srhu+QdOnC/yC0Q96bOwELTm3bhk qrz/6IASRjGL5WlC4jQPlPTFux6muRM6XBJWPteLnm2AauVdvxc3BiVChd2qyQ== Date: Wed, 8 May 2024 11:39:49 +0000 From: "Pankaj Raghav (Samsung)" To: Christoph Hellwig Cc: hch@lst.de, willy@infradead.org, mcgrof@kernel.org, akpm@linux-foundation.org, brauner@kernel.org, chandan.babu@oracle.com, david@fromorbit.com, djwong@kernel.org, gost.dev@samsung.com, hare@suse.de, john.g.garry@oracle.com, linux-block@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-xfs@vger.kernel.org, p.raghav@samsung.com, ritesh.list@gmail.com, ziy@nvidia.com Subject: Re: [RFC] iomap: use huge zero folio in iomap_dio_zero Message-ID: <20240508113949.pwyeavrc2rrwsxw2@quentin> References: <20240503095353.3798063-8-mcgrof@kernel.org> <20240507145811.52987-1-kernel@pankajraghav.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 2015D180028 X-Stat-Signature: bfa5eebs5s3jhaqefqbkq5rinkmxtjb4 X-Rspam-User: X-HE-Tag: 1715168397-553201 X-HE-Meta: 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 jvLJ+rJq 6a3xthXYZVVjv4vRhJ6RXFRU9/blNo/Xn719IoKvMEY3IJrGWLPH345Icr1GxhYgIoF8rvDxUAZZu/jjSuWe26NK4bD3BfNoyJh2d8dqD3I/g1hT0jpLIMVB4kgoYaZxIp/Kb5L+cxLwa0+ELUvrHcQcBO97xfnBTC10UDS7HvXJ+WkYjWXK1C61J7wQH42H87AaDJt/Jm0/s30X9aEFYvR8YAZI1WXIUhBui+1PryR864pJGflMJKuUmrGw1JmalGeaL7RtkAQydSMPO2X3l/1dw7dZuc5rCN7qK2i5wZSP3lVBqYkDc3a0/WA== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000099, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, May 07, 2024 at 09:11:51AM -0700, Christoph Hellwig wrote: > On Tue, May 07, 2024 at 04:58:12PM +0200, Pankaj Raghav (Samsung) wrote: > > + if (len > PAGE_SIZE) { > > + folio = mm_get_huge_zero_folio(current->mm); > > I don't think the mm_struct based interfaces work well here, as I/O > completions don't come in through the same mm. You'll want to use > lower level interfaces like get_huge_zero_page and use them at > mount time. At the moment, we can get a reference to the huge zero folio only through the mm interface. Even if change the lower level interface to return THP, it can still fail at the mount time and we will need the fallback right? > > > + if (!folio) > > + folio = zero_page_folio; > > And then don't bother with a fallback. > -- Pankaj Raghav