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[156.34.48.30]) by smtp.gmail.com with ESMTPSA id g1sm6069368qtp.74.2020.10.09.05.31.10 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 09 Oct 2020 05:31:10 -0700 (PDT) Received: from jgg by mlx with local (Exim 4.94) (envelope-from ) id 1kQrYD-001xsF-Sz; Fri, 09 Oct 2020 09:31:09 -0300 Date: Fri, 9 Oct 2020 09:31:09 -0300 From: Jason Gunthorpe To: Daniel Vetter Cc: DRI Development , LKML , kvm@vger.kernel.org, linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org, linux-samsung-soc@vger.kernel.org, linux-media@vger.kernel.org, linux-s390@vger.kernel.org, Daniel Vetter , Kees Cook , Dan Williams , Andrew Morton , John Hubbard , =?utf-8?B?SsOpcsO0bWU=?= Glisse , Jan Kara , Arnd Bergmann , Greg Kroah-Hartman , David Hildenbrand , "Rafael J. Wysocki" Subject: Re: [PATCH v2 14/17] resource: Move devmem revoke code to resource framework Message-ID: <20201009123109.GO5177@ziepe.ca> References: <20201009075934.3509076-1-daniel.vetter@ffwll.ch> <20201009075934.3509076-15-daniel.vetter@ffwll.ch> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201009075934.3509076-15-daniel.vetter@ffwll.ch> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Oct 09, 2020 at 09:59:31AM +0200, Daniel Vetter wrote: > +struct address_space *iomem_get_mapping(void) > +{ > + return iomem_inode->i_mapping; This should pair an acquire with the release below > + /* > + * Publish /dev/mem initialized. > + * Pairs with smp_load_acquire() in revoke_iomem(). > + */ > + smp_store_release(&iomem_inode, inode); However, this seems abnormal, initcalls rarely do this kind of stuff with global data.. The kernel crashes if this fs_initcall is raced with iomem_get_mapping() due to the unconditional dereference, so I think it can be safely switched to a simple assignment. Jason 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=-3.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no 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 C62C0C433E7 for ; Fri, 9 Oct 2020 12:32:25 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (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 7E01122284 for ; Fri, 9 Oct 2020 12:32:25 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="HxCJU2ox"; dkim=fail reason="signature verification failed" (2048-bit key) header.d=ziepe.ca header.i=@ziepe.ca header.b="cdaBlGmB" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7E01122284 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=ziepe.ca Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Transfer-Encoding: Content-Type:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References:Message-ID: Subject:To:From:Date:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=Y5sfBDgd2d05XStLCIFj2s/9NdLfNuPxnRxPgl6p6yw=; b=HxCJU2oxlINGX6H5GX5frpT/Z Z7xpEdhoVbx4wTNvmDzgjs6UYY4K+W0lVk6stImkLIC6j1y8BU1Ck14EKo4PTqezYRwZlu4UiXvkz EvNqAK7lQxDa+jxSij8lfWXPoAO6hpHMOA9h+VAwuvDJH9qbxn9ArYnZg9+sDsMepDSutc3eXJk6K vpoQAFMO4RUvHz2uR/HhRSwbJ4qrKGoRLwLodHNgpizx6frSwfFmxpIR4gQ4xqUQkVx9wu6+zfkLI SVypsk78/IQqmk4wQr5pNpUWX6JbTdLasxkNMfyl8X8x6Ua15kr9wRmXBz5837tjxBwBe5Il5ziO3 oJQA7c+bA==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kQrYK-0000iA-Dl; Fri, 09 Oct 2020 12:31:16 +0000 Received: from mail-qt1-x841.google.com ([2607:f8b0:4864:20::841]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1kQrYH-0000go-Ir for linux-arm-kernel@lists.infradead.org; Fri, 09 Oct 2020 12:31:14 +0000 Received: by mail-qt1-x841.google.com with SMTP id g3so7724665qtq.10 for ; Fri, 09 Oct 2020 05:31:12 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ziepe.ca; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=K8oqjNwy1IItwzS5nAtnJfKoqbYdlnvHoUJ/yQIxMlE=; b=cdaBlGmBZL4cakXZlvJuZERmIRIX6jD7dwzimgC10KWdoWEXxqnVyCAO2D0RVxCrE3 SiHI343vdap2cRRglH6ua6mGWuo7/fxfox6RkGqmDhIsAnKFSeohUX9VYGJSKAwhIU6B 2TcxKC37KpT1QUH/a9OmlQtDEo327+kakIXLdXGqBOKFhRN4BS67JiDu+bvG4a5CPI+r pqcyhIAj+gFL2/lmzDWusy4E62ErCo67w+IagQCo+gX4l+6CaOr61WFu2i1yy0l+Wgf3 xGuhQ4gDKh6os3wK0BjatM5g2y6nWPQvLIHBtHwaCM52uhc/sKGK0XWe8qKcZr9st8fm fLCQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=K8oqjNwy1IItwzS5nAtnJfKoqbYdlnvHoUJ/yQIxMlE=; b=AbvYbfIdkkGIffLPFvpHfwIRcL5G+k4ndRcRVsIsrdJc8ZAUiDZuIPFmQE11nAZY6I XK6vwkEhhIilybCWVGn6eutCHtcbSibSNqnYg8jS+G5EoNrsKq/R8GPsT2Jx7uteIeNJ 2PCVfXDjrbzqC6ECjxJKz0ovx2jdVmSLPqjCC9XxhQ/Da/T3HEQFI5PQ6M1q3CUOFlIj odkIDFS8AO0BXMhgHID/dAdaww8y+jmley0rHyFZcmlWXHHZbmDmEkY6IutOs2NskwQf 5BYNVGu3V05qWz2KZgwdayOiPuUSHBM7ruY0DDvfr6u3AnjXJlxCCC1PJnati82CLgeY G1SQ== X-Gm-Message-State: AOAM532PS23YhRsoE7upZrtCqixHhIvg4dbHcl4Hw5eH7ufZtjTF5m2Z IYfI6zyWSLU6AppUzn1GQQaPo12OyMNxN97c X-Google-Smtp-Source: ABdhPJxG8zCIXDditfEGKgb8JSFeGI61awPyS7AMuV2YFh9LkEtvSTVL1XgAfKTEjxIzUEviyqvgUw== X-Received: by 2002:ac8:d8d:: with SMTP id s13mr12568868qti.42.1602246671500; Fri, 09 Oct 2020 05:31:11 -0700 (PDT) Received: from ziepe.ca (hlfxns017vw-156-34-48-30.dhcp-dynamic.fibreop.ns.bellaliant.net. [156.34.48.30]) by smtp.gmail.com with ESMTPSA id g1sm6069368qtp.74.2020.10.09.05.31.10 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 09 Oct 2020 05:31:10 -0700 (PDT) Received: from jgg by mlx with local (Exim 4.94) (envelope-from ) id 1kQrYD-001xsF-Sz; Fri, 09 Oct 2020 09:31:09 -0300 Date: Fri, 9 Oct 2020 09:31:09 -0300 From: Jason Gunthorpe To: Daniel Vetter Subject: Re: [PATCH v2 14/17] resource: Move devmem revoke code to resource framework Message-ID: <20201009123109.GO5177@ziepe.ca> References: <20201009075934.3509076-1-daniel.vetter@ffwll.ch> <20201009075934.3509076-15-daniel.vetter@ffwll.ch> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20201009075934.3509076-15-daniel.vetter@ffwll.ch> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20201009_083113_635072_47A30694 X-CRM114-Status: GOOD ( 13.95 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-s390@vger.kernel.org, linux-samsung-soc@vger.kernel.org, Jan Kara , Kees Cook , kvm@vger.kernel.org, David Hildenbrand , John Hubbard , "Rafael J. Wysocki" , LKML , DRI Development , linux-mm@kvack.org, =?utf-8?B?SsOpcsO0bWU=?= Glisse , Arnd Bergmann , Greg Kroah-Hartman , Daniel Vetter , Dan Williams , Andrew Morton , linux-arm-kernel@lists.infradead.org, linux-media@vger.kernel.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Fri, Oct 09, 2020 at 09:59:31AM +0200, Daniel Vetter wrote: > +struct address_space *iomem_get_mapping(void) > +{ > + return iomem_inode->i_mapping; This should pair an acquire with the release below > + /* > + * Publish /dev/mem initialized. > + * Pairs with smp_load_acquire() in revoke_iomem(). > + */ > + smp_store_release(&iomem_inode, inode); However, this seems abnormal, initcalls rarely do this kind of stuff with global data.. The kernel crashes if this fs_initcall is raced with iomem_get_mapping() due to the unconditional dereference, so I think it can be safely switched to a simple assignment. Jason _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel 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=-3.5 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED autolearn=no 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 B9C0FC433E7 for ; Sat, 10 Oct 2020 10:03:01 +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 4DBAF21655 for ; Sat, 10 Oct 2020 10:03:01 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=ziepe.ca header.i=@ziepe.ca header.b="cdaBlGmB" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4DBAF21655 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=ziepe.ca 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 39A786E091; Sat, 10 Oct 2020 10:02:58 +0000 (UTC) Received: from mail-qt1-x842.google.com (mail-qt1-x842.google.com [IPv6:2607:f8b0:4864:20::842]) by gabe.freedesktop.org (Postfix) with ESMTPS id 501606ECAB for ; Fri, 9 Oct 2020 12:31:12 +0000 (UTC) Received: by mail-qt1-x842.google.com with SMTP id t9so6929411qtp.9 for ; Fri, 09 Oct 2020 05:31:12 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ziepe.ca; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=K8oqjNwy1IItwzS5nAtnJfKoqbYdlnvHoUJ/yQIxMlE=; b=cdaBlGmBZL4cakXZlvJuZERmIRIX6jD7dwzimgC10KWdoWEXxqnVyCAO2D0RVxCrE3 SiHI343vdap2cRRglH6ua6mGWuo7/fxfox6RkGqmDhIsAnKFSeohUX9VYGJSKAwhIU6B 2TcxKC37KpT1QUH/a9OmlQtDEo327+kakIXLdXGqBOKFhRN4BS67JiDu+bvG4a5CPI+r pqcyhIAj+gFL2/lmzDWusy4E62ErCo67w+IagQCo+gX4l+6CaOr61WFu2i1yy0l+Wgf3 xGuhQ4gDKh6os3wK0BjatM5g2y6nWPQvLIHBtHwaCM52uhc/sKGK0XWe8qKcZr9st8fm fLCQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=K8oqjNwy1IItwzS5nAtnJfKoqbYdlnvHoUJ/yQIxMlE=; b=LoWDDHRBq58MgfZQPBJQLpyDszMfsWayVGzEcEBV+JbO2HFwEcYRnjUq2MLs/6ZM81 Akm+JIshSReJ5LCR0CFIDcQORZyF3eg9Fy0/DOmy2zagOGY48SREdLiOqce4GBjE+4RO z3ey7s6Jr87mXB6molDkpj8ndjqpMwsz9hkPlY1GxEesGjQcwU4Vtv4+2chj/LmGUt8Q vYbGkADOBsb7ojaiSCPXaNiob2PIQlqOxZSyoYdMDA+1R/8uxOX2rcAyHtixyChlgTrA QkTMR6274mGeoPoJ4Mq73oBYnt2vu6giqW5KO1BLUdOEdWGAJNXqpFhL4Jl9YPpKZlm4 Brew== X-Gm-Message-State: AOAM533B5hI4AMlEAtE9ckXuNkZ2FFn9AYzin0GDZpwGw7wGvdgNlipI dFWU8YdtuSm6wsWbyC3yFsj8CQ== X-Google-Smtp-Source: ABdhPJxG8zCIXDditfEGKgb8JSFeGI61awPyS7AMuV2YFh9LkEtvSTVL1XgAfKTEjxIzUEviyqvgUw== X-Received: by 2002:ac8:d8d:: with SMTP id s13mr12568868qti.42.1602246671500; Fri, 09 Oct 2020 05:31:11 -0700 (PDT) Received: from ziepe.ca (hlfxns017vw-156-34-48-30.dhcp-dynamic.fibreop.ns.bellaliant.net. [156.34.48.30]) by smtp.gmail.com with ESMTPSA id g1sm6069368qtp.74.2020.10.09.05.31.10 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 09 Oct 2020 05:31:10 -0700 (PDT) Received: from jgg by mlx with local (Exim 4.94) (envelope-from ) id 1kQrYD-001xsF-Sz; Fri, 09 Oct 2020 09:31:09 -0300 Date: Fri, 9 Oct 2020 09:31:09 -0300 From: Jason Gunthorpe To: Daniel Vetter Subject: Re: [PATCH v2 14/17] resource: Move devmem revoke code to resource framework Message-ID: <20201009123109.GO5177@ziepe.ca> References: <20201009075934.3509076-1-daniel.vetter@ffwll.ch> <20201009075934.3509076-15-daniel.vetter@ffwll.ch> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20201009075934.3509076-15-daniel.vetter@ffwll.ch> X-Mailman-Approved-At: Sat, 10 Oct 2020 10:02:57 +0000 X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-s390@vger.kernel.org, linux-samsung-soc@vger.kernel.org, Jan Kara , Kees Cook , kvm@vger.kernel.org, David Hildenbrand , John Hubbard , "Rafael J. Wysocki" , LKML , DRI Development , linux-mm@kvack.org, =?utf-8?B?SsOpcsO0bWU=?= Glisse , Arnd Bergmann , Greg Kroah-Hartman , Daniel Vetter , Dan Williams , Andrew Morton , linux-arm-kernel@lists.infradead.org, linux-media@vger.kernel.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" On Fri, Oct 09, 2020 at 09:59:31AM +0200, Daniel Vetter wrote: > +struct address_space *iomem_get_mapping(void) > +{ > + return iomem_inode->i_mapping; This should pair an acquire with the release below > + /* > + * Publish /dev/mem initialized. > + * Pairs with smp_load_acquire() in revoke_iomem(). > + */ > + smp_store_release(&iomem_inode, inode); However, this seems abnormal, initcalls rarely do this kind of stuff with global data.. The kernel crashes if this fs_initcall is raced with iomem_get_mapping() due to the unconditional dereference, so I think it can be safely switched to a simple assignment. Jason _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel