From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 85167C432C0 for ; Fri, 29 Nov 2019 14:40:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 61EA721736 for ; Fri, 29 Nov 2019 14:40:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726897AbfK2Okg (ORCPT ); Fri, 29 Nov 2019 09:40:36 -0500 Received: from foss.arm.com ([217.140.110.172]:48672 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726902AbfK2Okg (ORCPT ); Fri, 29 Nov 2019 09:40:36 -0500 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 140851FB; Fri, 29 Nov 2019 06:40:36 -0800 (PST) Received: from [10.1.194.43] (e112269-lin.cambridge.arm.com [10.1.194.43]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 5EF483F6C4; Fri, 29 Nov 2019 06:40:35 -0800 (PST) Subject: Re: [PATCH 2/8] drm/panfrost: Fix a race in panfrost_ioctl_madvise() To: Boris Brezillon Cc: stable@vger.kernel.org, dri-devel@lists.freedesktop.org, Rob Herring , Alyssa Rosenzweig References: <20191129135908.2439529-1-boris.brezillon@collabora.com> <20191129135908.2439529-3-boris.brezillon@collabora.com> <20191129153310.2f9c80e1@collabora.com> From: Steven Price Message-ID: Date: Fri, 29 Nov 2019 14:40:34 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.2.2 MIME-Version: 1.0 In-Reply-To: <20191129153310.2f9c80e1@collabora.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org 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. Steve >> >>> >>> The easiest solution to fix that is to protect the >>> drm_gem_shmem_madvise() call with the shrinker lock. >>> >>> Fixes: 013b65101315 ("drm/panfrost: Add madvise and shrinker support") >>> Cc: >>> Signed-off-by: Boris Brezillon >> >> Reviewed-by: Steven Price > > Thanks. > >> >>> --- >>> drivers/gpu/drm/panfrost/panfrost_drv.c | 9 ++++----- >>> 1 file changed, 4 insertions(+), 5 deletions(-) >>> >>> diff --git a/drivers/gpu/drm/panfrost/panfrost_drv.c b/drivers/gpu/drm/panfrost/panfrost_drv.c >>> index f21bc8a7ee3a..efc0a24d1f4c 100644 >>> --- a/drivers/gpu/drm/panfrost/panfrost_drv.c >>> +++ b/drivers/gpu/drm/panfrost/panfrost_drv.c >>> @@ -347,20 +347,19 @@ static int panfrost_ioctl_madvise(struct drm_device *dev, void *data, >>> return -ENOENT; >>> } >>> >>> + mutex_lock(&pfdev->shrinker_lock); >>> args->retained = drm_gem_shmem_madvise(gem_obj, args->madv); >>> >>> if (args->retained) { >>> struct panfrost_gem_object *bo = to_panfrost_bo(gem_obj); >>> >>> - mutex_lock(&pfdev->shrinker_lock); >>> - >>> if (args->madv == PANFROST_MADV_DONTNEED) >>> - list_add_tail(&bo->base.madv_list, &pfdev->shrinker_list); >>> + list_add_tail(&bo->base.madv_list, >>> + &pfdev->shrinker_list); >>> else if (args->madv == PANFROST_MADV_WILLNEED) >>> list_del_init(&bo->base.madv_list); >>> - >>> - mutex_unlock(&pfdev->shrinker_lock); >>> } >>> + mutex_unlock(&pfdev->shrinker_lock); >>> >>> drm_gem_object_put_unlocked(gem_obj); >>> return 0; >>> >> > > _______________________________________________ > dri-devel mailing list > dri-devel@lists.freedesktop.org > https://lists.freedesktop.org/mailman/listinfo/dri-devel > From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1930EC432C3 for ; Fri, 29 Nov 2019 14:40:39 +0000 (UTC) Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id E9AE921736 for ; Fri, 29 Nov 2019 14:40:38 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E9AE921736 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=dri-devel-bounces@lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 4728C6E925; Fri, 29 Nov 2019 14:40:38 +0000 (UTC) Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by gabe.freedesktop.org (Postfix) with ESMTP id 6AB2C6E925 for ; Fri, 29 Nov 2019 14:40:36 +0000 (UTC) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 140851FB; Fri, 29 Nov 2019 06:40:36 -0800 (PST) Received: from [10.1.194.43] (e112269-lin.cambridge.arm.com [10.1.194.43]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 5EF483F6C4; Fri, 29 Nov 2019 06:40:35 -0800 (PST) Subject: Re: [PATCH 2/8] drm/panfrost: Fix a race in panfrost_ioctl_madvise() To: Boris Brezillon References: <20191129135908.2439529-1-boris.brezillon@collabora.com> <20191129135908.2439529-3-boris.brezillon@collabora.com> <20191129153310.2f9c80e1@collabora.com> From: Steven Price Message-ID: Date: Fri, 29 Nov 2019 14:40:34 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.2.2 MIME-Version: 1.0 In-Reply-To: <20191129153310.2f9c80e1@collabora.com> Content-Language: en-US X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Rob Herring , dri-devel@lists.freedesktop.org, stable@vger.kernel.org, Alyssa Rosenzweig Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" Message-ID: <20191129144034.mX4LIuTfa_dswG5nNxrNEDWBCPXd8k_VG9mObbicHts@z> T24gMjkvMTEvMjAxOSAxNDozMywgQm9yaXMgQnJlemlsbG9uIHdyb3RlOgo+IE9uIEZyaSwgMjkg Tm92IDIwMTkgMTQ6MjQ6NDggKzAwMDAKPiBTdGV2ZW4gUHJpY2UgPHN0ZXZlbi5wcmljZUBhcm0u Y29tPiB3cm90ZToKPiAKPj4gT24gMjkvMTEvMjAxOSAxMzo1OSwgQm9yaXMgQnJlemlsbG9uIHdy b3RlOgo+Pj4gSWYgMiB0aHJlYWRzIGNoYW5nZSB0aGUgTUFEVklTRSBwcm9wZXJ0eSBvZiB0aGUg c2FtZSBCTyBpbiBwYXJhbGxlbCB3ZQo+Pj4gbWlnaHQgZW5kIHVwIHdpdGggYW4gc2htZW0tPm1h ZHYgdmFsdWUgdGhhdCdzIGluY29uc2lzdGVudCB3aXRoIHRoZQo+Pj4gcHJlc2VuY2Ugb2YgdGhl IEJPIGluIHRoZSBzaHJpbmtlciBsaXN0LiAgCj4+Cj4+IEknbSBhIGJpdCB3b3JyaWVkIGZyb20g dGhlIHBvaW50IG9mIHZpZXcgb2YgdXNlciBzcGFjZSBzYW5pdHkgdGhhdCB5b3UKPj4gb2JzZXJ2 ZWQgdGhpcyAtIGJ1dCBjbGVhcmx5IHRoZSBrZXJuZWwgc2hvdWxkIGJlIHJvYnVzdCEKPiAKPiBJ dCdzIG5vdCBzb21ldGhpbmcgSSBvYnNlcnZlZCwganVzdCBmb3VuZCB0aGUgcmFjZSBieSBpbnNw ZWN0aW5nIHRoZQo+IGNvZGUsIGFuZCBJIHRob3VnaHQgaXQgd2FzIHdvcnRoIGZpeGluZyBpdC4K Ckdvb2QhIDspIFlvdXIgY292ZXIgbGV0dGVyIHJlZmVycmluZyB0byBhICJkZWJ1ZyBzZXNzaW9u IiBtYWRlIG1lIHRoaW5rCnlvdSdkIGFjdHVhbGx5IGhpdCBhbGwgdGhlc2UuCgpTdGV2ZQoKPj4K Pj4+Cj4+PiBUaGUgZWFzaWVzdCBzb2x1dGlvbiB0byBmaXggdGhhdCBpcyB0byBwcm90ZWN0IHRo ZQo+Pj4gZHJtX2dlbV9zaG1lbV9tYWR2aXNlKCkgY2FsbCB3aXRoIHRoZSBzaHJpbmtlciBsb2Nr Lgo+Pj4KPj4+IEZpeGVzOiAwMTNiNjUxMDEzMTUgKCJkcm0vcGFuZnJvc3Q6IEFkZCBtYWR2aXNl IGFuZCBzaHJpbmtlciBzdXBwb3J0IikKPj4+IENjOiA8c3RhYmxlQHZnZXIua2VybmVsLm9yZz4K Pj4+IFNpZ25lZC1vZmYtYnk6IEJvcmlzIEJyZXppbGxvbiA8Ym9yaXMuYnJlemlsbG9uQGNvbGxh Ym9yYS5jb20+ICAKPj4KPj4gUmV2aWV3ZWQtYnk6IFN0ZXZlbiBQcmljZSA8c3RldmVuLnByaWNl QGFybS5jb20+Cj4gCj4gVGhhbmtzLgo+IAo+Pgo+Pj4gLS0tCj4+PiAgZHJpdmVycy9ncHUvZHJt L3BhbmZyb3N0L3BhbmZyb3N0X2Rydi5jIHwgOSArKysrLS0tLS0KPj4+ICAxIGZpbGUgY2hhbmdl ZCwgNCBpbnNlcnRpb25zKCspLCA1IGRlbGV0aW9ucygtKQo+Pj4KPj4+IGRpZmYgLS1naXQgYS9k cml2ZXJzL2dwdS9kcm0vcGFuZnJvc3QvcGFuZnJvc3RfZHJ2LmMgYi9kcml2ZXJzL2dwdS9kcm0v cGFuZnJvc3QvcGFuZnJvc3RfZHJ2LmMKPj4+IGluZGV4IGYyMWJjOGE3ZWUzYS4uZWZjMGEyNGQx ZjRjIDEwMDY0NAo+Pj4gLS0tIGEvZHJpdmVycy9ncHUvZHJtL3BhbmZyb3N0L3BhbmZyb3N0X2Ry di5jCj4+PiArKysgYi9kcml2ZXJzL2dwdS9kcm0vcGFuZnJvc3QvcGFuZnJvc3RfZHJ2LmMKPj4+ IEBAIC0zNDcsMjAgKzM0NywxOSBAQCBzdGF0aWMgaW50IHBhbmZyb3N0X2lvY3RsX21hZHZpc2Uo c3RydWN0IGRybV9kZXZpY2UgKmRldiwgdm9pZCAqZGF0YSwKPj4+ICAJCXJldHVybiAtRU5PRU5U Owo+Pj4gIAl9Cj4+PiAgCj4+PiArCW11dGV4X2xvY2soJnBmZGV2LT5zaHJpbmtlcl9sb2NrKTsK Pj4+ICAJYXJncy0+cmV0YWluZWQgPSBkcm1fZ2VtX3NobWVtX21hZHZpc2UoZ2VtX29iaiwgYXJn cy0+bWFkdik7Cj4+PiAgCj4+PiAgCWlmIChhcmdzLT5yZXRhaW5lZCkgewo+Pj4gIAkJc3RydWN0 IHBhbmZyb3N0X2dlbV9vYmplY3QgKmJvID0gdG9fcGFuZnJvc3RfYm8oZ2VtX29iaik7Cj4+PiAg Cj4+PiAtCQltdXRleF9sb2NrKCZwZmRldi0+c2hyaW5rZXJfbG9jayk7Cj4+PiAtCj4+PiAgCQlp ZiAoYXJncy0+bWFkdiA9PSBQQU5GUk9TVF9NQURWX0RPTlRORUVEKQo+Pj4gLQkJCWxpc3RfYWRk X3RhaWwoJmJvLT5iYXNlLm1hZHZfbGlzdCwgJnBmZGV2LT5zaHJpbmtlcl9saXN0KTsKPj4+ICsJ CQlsaXN0X2FkZF90YWlsKCZiby0+YmFzZS5tYWR2X2xpc3QsCj4+PiArCQkJCSAgICAgICZwZmRl di0+c2hyaW5rZXJfbGlzdCk7Cj4+PiAgCQllbHNlIGlmIChhcmdzLT5tYWR2ID09IFBBTkZST1NU X01BRFZfV0lMTE5FRUQpCj4+PiAgCQkJbGlzdF9kZWxfaW5pdCgmYm8tPmJhc2UubWFkdl9saXN0 KTsKPj4+IC0KPj4+IC0JCW11dGV4X3VubG9jaygmcGZkZXYtPnNocmlua2VyX2xvY2spOwo+Pj4g IAl9Cj4+PiArCW11dGV4X3VubG9jaygmcGZkZXYtPnNocmlua2VyX2xvY2spOwo+Pj4gIAo+Pj4g IAlkcm1fZ2VtX29iamVjdF9wdXRfdW5sb2NrZWQoZ2VtX29iaik7Cj4+PiAgCXJldHVybiAwOwo+ Pj4gICAKPj4KPiAKPiBfX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19f X19fXwo+IGRyaS1kZXZlbCBtYWlsaW5nIGxpc3QKPiBkcmktZGV2ZWxAbGlzdHMuZnJlZWRlc2t0 b3Aub3JnCj4gaHR0cHM6Ly9saXN0cy5mcmVlZGVza3RvcC5vcmcvbWFpbG1hbi9saXN0aW5mby9k cmktZGV2ZWwKPiAKCl9fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19f X19fCmRyaS1kZXZlbCBtYWlsaW5nIGxpc3QKZHJpLWRldmVsQGxpc3RzLmZyZWVkZXNrdG9wLm9y ZwpodHRwczovL2xpc3RzLmZyZWVkZXNrdG9wLm9yZy9tYWlsbWFuL2xpc3RpbmZvL2RyaS1kZXZl bA==