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bh=A/yf/LULqe7cvpY9FNQQv9+HJYr9a5XLS/1CEJh4cUI=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=YCr1Wl0YP84wvIO2VnanRSDJFX8gKazY0fIbIaQQpeY8GwiC4hJKVKNwtW0q4LCzf t93zJ1seq5bE9yZRw83p/S4eY8irVRPlLZHE4zT70ZBfYBB8OH/X3eb29hyfK3F353 XbqPetAS+vr27HRFX6ytssh7f8WeSAZBa142EB+1TSWnufkB3VYtvjcFHm/6n9j9GZ jczUfeXFIjQA7EBXdX7DCGVMTVFYZ+tnHcgOjGY6svebxlSssNpgVxMIwRUPbwu7Dc NLTXt4JHsFOjeQllk02r4Aoh9kBaJnSVJN2MLSjmPTVdPELaClUG4Na86StyoAV/Jw Vnae3p4wKE9HA== Date: Thu, 8 Jun 2023 13:13:40 +0300 From: Mike Rapoport To: Michal Hocko Cc: Haifeng Xu , David Hildenbrand , akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm/mm_init.c: add debug messsge for dma zone Message-ID: <20230608101340.GI52412@kernel.org> References: <20230607090734.1259-1-haifeng.xu@shopee.com> <34f32148-24c3-09a3-8bec-9515139e15b1@shopee.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: A5FC2100014 X-Stat-Signature: zny4ai5yc9c6ehm94dq1i67qmtt5s6e5 X-Rspam-User: X-HE-Tag: 1686219247-261282 X-HE-Meta: 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 /c3lmuX8 Bx47dm0/DoROz8ihIlF9gYlm7xRnBdo20p6Er9rMNBJ8DBm6HdB7HImHfaUckA+V3GTIWaYDJQhq2xKCnYX6ueYiMvk96iB1T1zF5Vle7r1Fix8S721Q9cdxBJpDyxcEru4/abQMvuPwoZZH/CG3rwgmrplTpXqXrT9r+VNSHqLCSgTfZ0GM90fJ3cZKQIyF9rROHy+V9rYw+4XKeRqYdgTgAR4Yyvq6N1izRVnRB+B9KOHuUpocIz+GFBRf1oW7X2XKmvXui8K/y4eGU/Sey3UQsxRCtL8yrlxK9leFbHJjncl0ZxT+Ar/7D5NEbRrJiHyjr9NxTsrM1KQU= 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, Jun 08, 2023 at 11:18:02AM +0200, Michal Hocko wrote: > On Thu 08-06-23 15:38:48, Haifeng Xu wrote: > > > > > > On 2023/6/7 18:22, David Hildenbrand wrote: > > > On 07.06.23 12:16, Michal Hocko wrote: > > >> On Wed 07-06-23 09:07:34, Haifeng Xu wrote: > > >>> If freesize is less than dma_reserve, print warning message to report > > >>> this case. > > >> > > >> Why? > > > > > > I'd like to second that question, and add > > > > > > a) Did you run into that scenario? > > > b) What can an admin do in that case with that error messages? > > > > In theory，dma_reserve shouldn't exceed freesize, so the error messages can remind us > > to verify whether the configuration of reserved memory is correct. > > I am not really convinced this is worth touching the code TBH. The only architecture that sets the dma_reserve is x86_64 and it sets it to the number of reserved pages in DMA zone. There is no way freesize will be less than dma_reserve. I'm not sure that in general dma_reserve has some value now, but that's a completely different story. > -- > Michal Hocko > SUSE Labs -- Sincerely yours, Mike.