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Message-ID: <CAPcyv4h_axDTmkZ35KFfCdzMoOp8V3dc6btYGq6gCj1OmLXM=g@mail.gmail.com> Date: Tue, 8 Feb 2022 19:30:11 -0800 From: Dan Williams <dan.j.williams@...el.com> To: Christoph Hellwig <hch@....de> Cc: Andrew Morton <akpm@...ux-foundation.org>, Felix Kuehling <Felix.Kuehling@....com>, Alex Deucher <alexander.deucher@....com>, Christian König <christian.koenig@....com>, "Pan, Xinhui" <Xinhui.Pan@....com>, Ben Skeggs <bskeggs@...hat.com>, Karol Herbst <kherbst@...hat.com>, Lyude Paul <lyude@...hat.com>, Jason Gunthorpe <jgg@...pe.ca>, Alistair Popple <apopple@...dia.com>, Logan Gunthorpe <logang@...tatee.com>, Ralph Campbell <rcampbell@...dia.com>, Linux Kernel Mailing List <linux-kernel@...r.kernel.org>, amd-gfx list <amd-gfx@...ts.freedesktop.org>, Maling list - DRI developers <dri-devel@...ts.freedesktop.org>, nouveau@...ts.freedesktop.org, Linux NVDIMM <nvdimm@...ts.linux.dev>, Linux MM <linux-mm@...ck.org> Subject: Re: [PATCH 7/8] mm: remove the extra ZONE_DEVICE struct page refcount On Sun, Feb 6, 2022 at 10:33 PM Christoph Hellwig <hch@....de> wrote: [..] > @@ -500,28 +482,27 @@ void free_devmap_managed_page(struct page *page) > */ > page->mapping = NULL; > page->pgmap->ops->page_free(page); > + > + /* > + * Reset the page count to 1 to prepare for handing out the page again. > + */ > + set_page_count(page, 1); Interesting. I had expected that to really fix the refcount problem that fs/dax.c would need to start taking real page references as pages were added to a mapping, just like page cache. This looks ok to me, and passes my tests. So given I'm still working my way back to fixing the references properly I'm ok for this hack to replace the more broken hack that is there presently. Reviewed-by: Dan Williams <dan.j.williams@...el.com>
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