From mboxrd@z Thu Jan 1 00:00:00 1970 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: base64 Subject: dma-mapping: clearing GFP_ZERO flag caused crashes of Ethernet on arc/hsdk board. From: Christoph Hellwig Message-Id: <20180328075313.GA19864@lst.de> Date: Wed, 28 Mar 2018 09:53:13 +0200 To: Alexey Brodkin Cc: "andy.shevchenko@gmail.com" , "linux-kernel@vger.kernel.org" , "jesper.nilsson@axis.com" , "Eugeniy.Paltsev@synopsys.com" , "hch@lst.de" , "linux-snps-arc@lists.infradead.org" , "iommu@lists.linux-foundation.org" , "dmaengine@vger.kernel.org" , "Evgeniy.Didin@synopsys.com" , "geert@linux-m68k.org" List-ID: PiA+IFRoZSBsb2dpY2FsIHF1ZXN0aW9uIGlzIHdoeT8KPiAKPiAxLiBTZWUgdGhhdCdzIGFub3Ro ZXIgcGxhdGZvcm0gd2l0aCBBUkMgY29yZSBzbyBtYXliZSBpbiBjYXNlIG9mIEFSTQo+ICAgIERN QSBhbGxvY2F0b3IgYWxyZWFkeSB6ZXJvZXMgcGFnZXMgcmVnYXJkbGVzcyBwcm92aWRlZCBmbGFn cyAtCj4gICAgcGVyc29uYWxseSBJIGRpZG4ndCBjaGVjayB0aGF0LgoKWWVzLCBtb3N0IGFyY2hp dGVjdHVyZXMgYWx3YXlzIGNsZWFyIG1lbW9yeSByZXR1cm5lZCBieSBkbWFfYWxsb2MqLgpMb29r cyBsaWtlIGEgZmV3IGRvbid0IGFuZCBteSBjb21taXQgZ290IHRoZW0gaW4gdHJvdWJsZS4gIEFz IHVzdWFsCkknZCBwcmVmZXIgdG8gbWF0Y2ggeDg2IHNlbWFudGljcyBmb3Igbm93IHRvIGF2b2lk IHByb2JsZW1zLgoKSSdsbCBzZW5kIHBhdGNoZXMgZm9yIGFyYyBhbmQgczM5MCB3aGljaCBzZWVt IHRvIGJlIGFjdHVhbGx5IHVzZWQKaG9sZG91dHMsIGFuZCB3aWxsIGxvb2sgaWYgYW55b25lIGVs c2UgaXMgYWxzbyBhZmZlY3RlZC4KLS0tClRvIHVuc3Vic2NyaWJlIGZyb20gdGhpcyBsaXN0OiBz ZW5kIHRoZSBsaW5lICJ1bnN1YnNjcmliZSBkbWFlbmdpbmUiIGluCnRoZSBib2R5IG9mIGEgbWVz c2FnZSB0byBtYWpvcmRvbW9Admdlci5rZXJuZWwub3JnCk1vcmUgbWFqb3Jkb21vIGluZm8gYXQg IGh0dHA6Ly92Z2VyLmtlcm5lbC5vcmcvbWFqb3Jkb21vLWluZm8uaHRtbAo= From mboxrd@z Thu Jan 1 00:00:00 1970 From: "hch-jcswGhMUV9g@public.gmane.org" Subject: Re: dma-mapping: clearing GFP_ZERO flag caused crashes of Ethernet on arc/hsdk board. Date: Wed, 28 Mar 2018 09:53:13 +0200 Message-ID: <20180328075313.GA19864@lst.de> References: <1522170774.2593.9.camel@synopsys.com> <1522185558.6917.7.camel@synopsys.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <1522185558.6917.7.camel-HKixBCOQz3hWk0Htik3J/w@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: Alexey Brodkin Cc: "jesper.nilsson-VrBV9hrLPhE@public.gmane.org" , "linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org" , "Evgeniy.Didin-HKixBCOQz3hWk0Htik3J/w@public.gmane.org" , "andy.shevchenko-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org" , "geert-Td1EMuHUCqxL1ZNQvxDV9g@public.gmane.org" , "dmaengine-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "linux-snps-arc-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org" , "Eugeniy.Paltsev-HKixBCOQz3hWk0Htik3J/w@public.gmane.org" , "hch-jcswGhMUV9g@public.gmane.org" List-Id: iommu@lists.linux-foundation.org > > The logical question is why? > > 1. See that's another platform with ARC core so maybe in case of ARM > DMA allocator already zeroes pages regardless provided flags - > personally I didn't check that. Yes, most architectures always clear memory returned by dma_alloc*. Looks like a few don't and my commit got them in trouble. As usual I'd prefer to match x86 semantics for now to avoid problems. I'll send patches for arc and s390 which seem to be actually used holdouts, and will look if anyone else is also affected. From mboxrd@z Thu Jan 1 00:00:00 1970 From: hch@lst.de (hch@lst.de) Date: Wed, 28 Mar 2018 09:53:13 +0200 Subject: dma-mapping: clearing GFP_ZERO flag caused crashes of Ethernet on arc/hsdk board. In-Reply-To: <1522185558.6917.7.camel@synopsys.com> References: <1522170774.2593.9.camel@synopsys.com> <1522185558.6917.7.camel@synopsys.com> List-ID: Message-ID: <20180328075313.GA19864@lst.de> To: linux-snps-arc@lists.infradead.org > > The logical question is why? > > 1. See that's another platform with ARC core so maybe in case of ARM > DMA allocator already zeroes pages regardless provided flags - > personally I didn't check that. Yes, most architectures always clear memory returned by dma_alloc*. Looks like a few don't and my commit got them in trouble. As usual I'd prefer to match x86 semantics for now to avoid problems. I'll send patches for arc and s390 which seem to be actually used holdouts, and will look if anyone else is also affected. From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751750AbeC1HxQ (ORCPT ); Wed, 28 Mar 2018 03:53:16 -0400 Received: from verein.lst.de ([213.95.11.211]:44377 "EHLO newverein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750753AbeC1HxO (ORCPT ); Wed, 28 Mar 2018 03:53:14 -0400 Date: Wed, 28 Mar 2018 09:53:13 +0200 From: "hch@lst.de" To: Alexey Brodkin Cc: "andy.shevchenko@gmail.com" , "linux-kernel@vger.kernel.org" , "jesper.nilsson@axis.com" , "Eugeniy.Paltsev@synopsys.com" , "hch@lst.de" , "linux-snps-arc@lists.infradead.org" , "iommu@lists.linux-foundation.org" , "dmaengine@vger.kernel.org" , "Evgeniy.Didin@synopsys.com" , "geert@linux-m68k.org" Subject: Re: dma-mapping: clearing GFP_ZERO flag caused crashes of Ethernet on arc/hsdk board. Message-ID: <20180328075313.GA19864@lst.de> References: <1522170774.2593.9.camel@synopsys.com> <1522185558.6917.7.camel@synopsys.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1522185558.6917.7.camel@synopsys.com> User-Agent: Mutt/1.5.17 (2007-11-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > > The logical question is why? > > 1. See that's another platform with ARC core so maybe in case of ARM > DMA allocator already zeroes pages regardless provided flags - > personally I didn't check that. Yes, most architectures always clear memory returned by dma_alloc*. Looks like a few don't and my commit got them in trouble. As usual I'd prefer to match x86 semantics for now to avoid problems. I'll send patches for arc and s390 which seem to be actually used holdouts, and will look if anyone else is also affected.