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De Francesco" , Andrew Morton , Sebastian Andrzej Siewior , Alexander Potapenko , Andrey Konovalov , Tony Luck , Bagas Sanjaya , David Sterba , Kees Cook , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Thomas Gleixner , Al Viro Subject: Re: [PATCH] mm/highmem: Align-down to page the address for kunmap_flush_on_unmap() Message-ID: References: <20230126143346.12086-1-fmdefrancesco@gmail.com> <63d2d97bce4c7_63e3f29442@iweiny-mobl.notmuch> <804f9617-cdad-d3cb-f4c0-7d99d12f49d6@gmx.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <804f9617-cdad-d3cb-f4c0-7d99d12f49d6@gmx.de> X-Rspam-User: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 6939B1C0006 X-Stat-Signature: znshfbpkck5y8k9y617j58zn7yjaqqdr X-HE-Tag: 1674766190-28995 X-HE-Meta: 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 wRA9nNDk w+2zUjvCKn/6WTZQyZtTGgIurPlWH2+t8zCcJmwIy0da3itk2+M8DraUpgtV++KfAq4wTMy5iut6xrv/jJlH+7TU0Rok3pCtvxDrsyAdmCbGKpo6/PWWolWMmsmUsSza1QX2clV3d+I8E1FvsCyBHmhUMp4TGpNIK9IIo1aklUk/ZTcVaxTVVidyZjn80dxBymiwky5nyfX2qt+Y= 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 Thu, Jan 26, 2023 at 09:37:08PM +0100, Helge Deller wrote: > > This 'fixes' looks correct to me. I don't know how many folks are running > > highmem with parisc but if they are I am sure they would appreciate the > > extra knowledge. > > It seems nobody is running highmem on parisc, because it can't be enabled. > AFAICS, it's not in any parisc related Kconfig file. But this isn't being used for highmem on parisc; it's being used for cache coherency. > > I do wonder if this should be cc'ed to stable to ensure it gets > > backported? Helge do you think there is a need for that? > > For correctness I think it's nevertheless good to backport it. I cc'd stable on my version of this patch, and included a Fixes tag to indicate how far back to backport it. > That would be another possibility: > > diff --git a/arch/parisc/include/asm/cacheflush.h b/arch/parisc/include/asm/cacheflush.h > index 0bdee6724132..ce5d1f8a23bd 100644 > --- a/arch/parisc/include/asm/cacheflush.h > +++ b/arch/parisc/include/asm/cacheflush.h > @@ -77,6 +77,7 @@ void flush_anon_page(struct vm_area_struct *vma, struct page *page, unsigned lon > #define ARCH_HAS_FLUSH_ON_KUNMAP > static inline void kunmap_flush_on_unmap(const void *addr) > { > + addr = PTR_ALIGN_DOWN(addr, PAGE_SIZE); I considered that, but thought it a shame to do it here when all the other users are passing in a page-aligned address.