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Wong" To: Christoph Hellwig Cc: "Pankaj Raghav (Samsung)" , hch@lst.de, willy@infradead.org, mcgrof@kernel.org, akpm@linux-foundation.org, brauner@kernel.org, chandan.babu@oracle.com, david@fromorbit.com, 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: <20240509150828.GK360919@frogsfrogsfrogs> References: <20240507145811.52987-1-kernel@pankajraghav.com> <20240508113949.pwyeavrc2rrwsxw2@quentin> <20240509123107.hhi3lzjcn5svejvk@quentin> <20240509125514.2i3a7yo657frjqwq@quentin> <20240509143250.GF360919@frogsfrogsfrogs> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Stat-Signature: j1wezqozszn4ymm4t6w3wpw3ndmsejep X-Rspam-User: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 0C0624001C X-HE-Tag: 1715267313-349902 X-HE-Meta: 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 NYjMSr3v iUX2Ae4tr6VAEeuyry/M39Fj/TeY+bjwGY43vIJlKg/qdihKxuJLHhvnkMocr8GpD4Nedd6h7farY/1k15K5szMlH65JS9h81MxJKnGnJ6DFwZwfm5FoaLH7paWZ70lbPL9yj3mV45zIRyJg4aFfkMsG5gF1poatr5LwGVHdNoLuEcn71xoGHZGat4q7HQvT5TM0XLcmDYOr/RN3mSR9YO3HALHBp4PDjK6lc7i41EKpFzb7YWKmgW/bcJoKavwurIuZ6x12dawCweugorcO0Ha11/bimGoUbaKdXcG3AxnPSG7dc6T2J/2asXw== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000027, 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 Thu, May 09, 2024 at 08:05:24AM -0700, Christoph Hellwig wrote: > On Thu, May 09, 2024 at 07:32:50AM -0700, Darrick J. Wong wrote: > > On Thu, May 09, 2024 at 05:58:23AM -0700, Christoph Hellwig wrote: > > > On Thu, May 09, 2024 at 12:55:14PM +0000, Pankaj Raghav (Samsung) wrote: > > > > We might still fail here during mount. My question is: do we also fail > > > > the mount if folio_alloc fails? > > > > > > Yes. Like any other allocation that fails at mount time. > > > > How hard is it to fallback to regular zero-page if you can't allocate > > the zero-hugepage? > > We'd need the bio allocation and bio_add_page loop. Not the end > of the world, but also a bit annoying. If we do that we might as > well just do it unconditionally. > > > I think most sysadmins would rather mount with > > reduced zeroing performance than get an ENOMEM. > > If you don't have 2MB free for the zero huge folio, are you going to > do useful things with your large block size XFS file system which > only makes sense for giant storage sizes? Oh. Right, this is for bs>ps. For that case it makes sense to fail the mount. I was only thinking about bs<=ps with large folios, where it doesn't. (Would we use the zero-hugepage for large folios on a 4k fsblock fs?) --D