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[212.51.149.96]) by smtp.gmail.com with ESMTPSA id k8sm6431399wrl.3.2019.11.29.12.07.35 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 29 Nov 2019 12:07:35 -0800 (PST) Date: Fri, 29 Nov 2019 21:07:33 +0100 From: Daniel Vetter To: Steven Price Cc: Boris Brezillon , Rob Herring , dri-devel@lists.freedesktop.org, stable@vger.kernel.org, Alyssa Rosenzweig Subject: Re: [PATCH 2/8] drm/panfrost: Fix a race in panfrost_ioctl_madvise() Message-ID: <20191129200733.GQ624164@phenom.ffwll.local> References: <20191129135908.2439529-1-boris.brezillon@collabora.com> <20191129135908.2439529-3-boris.brezillon@collabora.com> <20191129153310.2f9c80e1@collabora.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Operating-System: Linux phenom 5.3.0-2-amd64 User-Agent: Mutt/1.12.2 (2019-09-21) Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org On Fri, Nov 29, 2019 at 02:40:34PM +0000, Steven Price wrote: > On 29/11/2019 14:33, Boris Brezillon wrote: > > On Fri, 29 Nov 2019 14:24:48 +0000 > > Steven Price wrote: > > > >> On 29/11/2019 13:59, Boris Brezillon wrote: > >>> If 2 threads change the MADVISE property of the same BO in parallel we > >>> might end up with an shmem->madv value that's inconsistent with the > >>> presence of the BO in the shrinker list. > >> > >> I'm a bit worried from the point of view of user space sanity that you > >> observed this - but clearly the kernel should be robust! > > > > It's not something I observed, just found the race by inspecting the > > code, and I thought it was worth fixing it. > > Good! ;) Your cover letter referring to a "debug session" made me think > you'd actually hit all these. Time for some igt to make sure this is actually correct? -Daniel -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch From mboxrd@z Thu Jan 1 00:00:00 1970 From: Daniel Vetter Subject: Re: [PATCH 2/8] drm/panfrost: Fix a race in panfrost_ioctl_madvise() Date: Fri, 29 Nov 2019 21:07:33 +0100 Message-ID: <20191129200733.GQ624164@phenom.ffwll.local> References: <20191129135908.2439529-1-boris.brezillon@collabora.com> <20191129135908.2439529-3-boris.brezillon@collabora.com> <20191129153310.2f9c80e1@collabora.com> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Return-path: Received: from mail-wm1-x342.google.com (mail-wm1-x342.google.com [IPv6:2a00:1450:4864:20::342]) by gabe.freedesktop.org (Postfix) with ESMTPS id A2B3B6E970 for ; Fri, 29 Nov 2019 20:07:37 +0000 (UTC) Received: by mail-wm1-x342.google.com with SMTP id p9so267488wmc.2 for ; Fri, 29 Nov 2019 12:07:37 -0800 (PST) Content-Disposition: inline In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" To: Steven Price Cc: stable@vger.kernel.org, Boris Brezillon , dri-devel@lists.freedesktop.org, Rob Herring , Alyssa Rosenzweig List-Id: dri-devel@lists.freedesktop.org T24gRnJpLCBOb3YgMjksIDIwMTkgYXQgMDI6NDA6MzRQTSArMDAwMCwgU3RldmVuIFByaWNlIHdy b3RlOgo+IE9uIDI5LzExLzIwMTkgMTQ6MzMsIEJvcmlzIEJyZXppbGxvbiB3cm90ZToKPiA+IE9u IEZyaSwgMjkgTm92IDIwMTkgMTQ6MjQ6NDggKzAwMDAKPiA+IFN0ZXZlbiBQcmljZSA8c3RldmVu LnByaWNlQGFybS5jb20+IHdyb3RlOgo+ID4gCj4gPj4gT24gMjkvMTEvMjAxOSAxMzo1OSwgQm9y aXMgQnJlemlsbG9uIHdyb3RlOgo+ID4+PiBJZiAyIHRocmVhZHMgY2hhbmdlIHRoZSBNQURWSVNF IHByb3BlcnR5IG9mIHRoZSBzYW1lIEJPIGluIHBhcmFsbGVsIHdlCj4gPj4+IG1pZ2h0IGVuZCB1 cCB3aXRoIGFuIHNobWVtLT5tYWR2IHZhbHVlIHRoYXQncyBpbmNvbnNpc3RlbnQgd2l0aCB0aGUK PiA+Pj4gcHJlc2VuY2Ugb2YgdGhlIEJPIGluIHRoZSBzaHJpbmtlciBsaXN0LiAgCj4gPj4KPiA+ PiBJJ20gYSBiaXQgd29ycmllZCBmcm9tIHRoZSBwb2ludCBvZiB2aWV3IG9mIHVzZXIgc3BhY2Ug c2FuaXR5IHRoYXQgeW91Cj4gPj4gb2JzZXJ2ZWQgdGhpcyAtIGJ1dCBjbGVhcmx5IHRoZSBrZXJu ZWwgc2hvdWxkIGJlIHJvYnVzdCEKPiA+IAo+ID4gSXQncyBub3Qgc29tZXRoaW5nIEkgb2JzZXJ2 ZWQsIGp1c3QgZm91bmQgdGhlIHJhY2UgYnkgaW5zcGVjdGluZyB0aGUKPiA+IGNvZGUsIGFuZCBJ IHRob3VnaHQgaXQgd2FzIHdvcnRoIGZpeGluZyBpdC4KPiAKPiBHb29kISA7KSBZb3VyIGNvdmVy IGxldHRlciByZWZlcnJpbmcgdG8gYSAiZGVidWcgc2Vzc2lvbiIgbWFkZSBtZSB0aGluawo+IHlv dSdkIGFjdHVhbGx5IGhpdCBhbGwgdGhlc2UuCgpUaW1lIGZvciBzb21lIGlndCB0byBtYWtlIHN1 cmUgdGhpcyBpcyBhY3R1YWxseSBjb3JyZWN0PwotRGFuaWVsCi0tIApEYW5pZWwgVmV0dGVyClNv ZnR3YXJlIEVuZ2luZWVyLCBJbnRlbCBDb3Jwb3JhdGlvbgpodHRwOi8vYmxvZy5mZndsbC5jaApf X19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fXwpkcmktZGV2ZWwg bWFpbGluZyBsaXN0CmRyaS1kZXZlbEBsaXN0cy5mcmVlZGVza3RvcC5vcmcKaHR0cHM6Ly9saXN0 cy5mcmVlZGVza3RvcC5vcmcvbWFpbG1hbi9saXN0aW5mby9kcmktZGV2ZWw=