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=-3.9 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS 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 D5BAFC47425 for ; Tue, 29 Sep 2020 08:19:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9803A20773 for ; Tue, 29 Sep 2020 08:19:46 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=suse.com header.i=@suse.com header.b="SSpMjosS" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727660AbgI2ITp (ORCPT ); Tue, 29 Sep 2020 04:19:45 -0400 Received: from mx2.suse.de ([195.135.220.15]:59520 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725550AbgI2ITo (ORCPT ); Tue, 29 Sep 2020 04:19:44 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1601367582; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=KFyfyEQCS1dcCR4BhfL+zwiQ3CuzyAy4x23tr+VkzjE=; b=SSpMjosSL8o4OPVa55QL9wIlM8PHwJpdBy+0T8Zs2+GxBxG6YA9l00PJ9Y66qcHmMfGLv9 u+g+tcEvJ7RxAvAP57LRStfEelxtPsdHOGOgFzbQCNh9qQZDiKdnSarvXzcr1YnPqWmMjI wdLRjalKNBbwgyGfH1Q3bT+vgMo4axA= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 3E86BADD8; Tue, 29 Sep 2020 08:19:42 +0000 (UTC) Date: Tue, 29 Sep 2020 10:19:38 +0200 From: Michal Hocko To: Daniel Vetter Cc: "Paul E. McKenney" , Juri Lelli , Peter Zijlstra , Sebastian Andrzej Siewior , Lai Jiangshan , dri-devel , Ben Segall , Linux-MM , "open list:KERNEL SELFTEST FRAMEWORK" , linux-hexagon@vger.kernel.org, Will Deacon , Ingo Molnar , Anton Ivanov , linux-arch , Vincent Guittot , Herbert Xu , Brian Cain , Richard Weinberger , Russell King , Ard Biesheuvel , David Airlie , Ingo Molnar , Geert Uytterhoeven , Mel Gorman , intel-gfx , Matt Turner , Valentin Schneider , linux-xtensa@linux-xtensa.org, Shuah Khan , Jeff Dike , linux-um , Josh Triplett , Steven Rostedt , rcu@vger.kernel.org, linux-m68k , Ivan Kokshaysky , Rodrigo Vivi , Thomas Gleixner , Dietmar Eggemann , Linux ARM , Richard Henderson , Chris Zankel , Max Filippov , Daniel Bristot de Oliveira , LKML , alpha , Mathieu Desnoyers , Andrew Morton , Linus Torvalds Subject: Re: [patch 00/13] preempt: Make preempt count unconditional Message-ID: <20200929081938.GC22035@dhcp22.suse.cz> References: <871rj4owfn.fsf@nanos.tec.linutronix.de> <87bli75t7v.fsf@nanos.tec.linutronix.de> <20200916152956.GV29330@paulmck-ThinkPad-P72> <20200916205840.GD29330@paulmck-ThinkPad-P72> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed 16-09-20 23:43:02, Daniel Vetter wrote: > I can > then figure out whether it's better to risk not spotting issues with > call_rcu vs slapping a memalloc_noio_save/restore around all these > critical section which force-degrades any allocation to GFP_ATOMIC at did you mean memalloc_noreclaim_* here? > most, but has the risk that we run into code that assumes "GFP_KERNEL > never fails for small stuff" and has a decidedly less tested fallback > path than rcu code. Even if the above then please note that memalloc_noreclaim_* or PF_MEMALLOC should be used with an extreme care. Essentially only for internal memory reclaimers. It grants access to _all_ the available memory so any abuse can be detrimental to the overall system operation. Allocation failure in this mode means that we are out of memory and any code relying on such an allocation has to carefuly consider failure. This is not a random allocation mode. -- Michal Hocko SUSE Labs 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=-3.9 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS 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 ECBC9C47420 for ; Tue, 29 Sep 2020 08:19:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 96F0F206C1 for ; Tue, 29 Sep 2020 08:19:55 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=suse.com header.i=@suse.com header.b="WFaQTV+k" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727727AbgI2ITy (ORCPT ); Tue, 29 Sep 2020 04:19:54 -0400 Received: from mx2.suse.de ([195.135.220.15]:59722 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727403AbgI2ITv (ORCPT ); Tue, 29 Sep 2020 04:19:51 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1601367589; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=KFyfyEQCS1dcCR4BhfL+zwiQ3CuzyAy4x23tr+VkzjE=; b=WFaQTV+kmp2Dcf4ETP9+6ZNrPfy9q5pMDECagrCQ3MjluCnYeqMkFTw/YcJHGz2iksDQw9 srvpAmlMUEz2D9SjbkwSKNyTXnnl0c+U97e7qNgFVE9O8k3lMFBfs0YlvFJAzRLJyf+n+C wZ5d1Zkp/fxHdHhoVK5syk5dxSgYigs= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id C7EE3B29F; Tue, 29 Sep 2020 08:19:48 +0000 (UTC) Date: Tue, 29 Sep 2020 10:19:48 +0200 From: Michal Hocko To: Daniel Vetter Cc: "Paul E. McKenney" , Juri Lelli , Peter Zijlstra , Sebastian Andrzej Siewior , Lai Jiangshan , dri-devel , Ben Segall , Linux-MM , "open list:KERNEL SELFTEST FRAMEWORK" , linux-hexagon@vger.kernel.org, Will Deacon , Ingo Molnar , Anton Ivanov , linux-arch , Vincent Guittot , Herbert Xu , Brian Cain , Richard Weinberger , Russell King , Ard Biesheuvel , David Airlie , Ingo Molnar , Geert Uytterhoeven , Mel Gorman , intel-gfx , Matt Turner , Valentin Schneider , linux-xtensa@linux-xtensa.org, Shuah Khan , Jeff Dike , linux-um , Josh Triplett , Steven Rostedt , rcu@vger.kernel.org, linux-m68k , Ivan Kokshaysky , Rodrigo Vivi , Thomas Gleixner , Dietmar Eggemann , Linux ARM , Richard Henderson , Chris Zankel , Max Filippov , Daniel Bristot de Oliveira , LKML , alpha , Mathieu Desnoyers , Andrew Morton , Linus Torvalds Subject: Re: [patch 00/13] preempt: Make preempt count unconditional Message-ID: <20200929081938.GC22035@dhcp22.suse.cz> References: <871rj4owfn.fsf@nanos.tec.linutronix.de> <87bli75t7v.fsf@nanos.tec.linutronix.de> <20200916152956.GV29330@paulmck-ThinkPad-P72> <20200916205840.GD29330@paulmck-ThinkPad-P72> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Message-ID: <20200929081948.SDjC7-smlKEyn9KXEOgghEpI67-_prbtXSlkyqUS-1s@z> On Wed 16-09-20 23:43:02, Daniel Vetter wrote: > I can > then figure out whether it's better to risk not spotting issues with > call_rcu vs slapping a memalloc_noio_save/restore around all these > critical section which force-degrades any allocation to GFP_ATOMIC at did you mean memalloc_noreclaim_* here? > most, but has the risk that we run into code that assumes "GFP_KERNEL > never fails for small stuff" and has a decidedly less tested fallback > path than rcu code. Even if the above then please note that memalloc_noreclaim_* or PF_MEMALLOC should be used with an extreme care. Essentially only for internal memory reclaimers. It grants access to _all_ the available memory so any abuse can be detrimental to the overall system operation. Allocation failure in this mode means that we are out of memory and any code relying on such an allocation has to carefuly consider failure. This is not a random allocation mode. -- Michal Hocko SUSE Labs 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=-3.9 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS 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 49FF4C4346E for ; Tue, 29 Sep 2020 08:20:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0663A206C1 for ; Tue, 29 Sep 2020 08:20:14 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=suse.com header.i=@suse.com header.b="pr56FUr2" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727753AbgI2IUN (ORCPT ); Tue, 29 Sep 2020 04:20:13 -0400 Received: from mx2.suse.de ([195.135.220.15]:60682 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727403AbgI2IUM (ORCPT ); Tue, 29 Sep 2020 04:20:12 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1601367609; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=KFyfyEQCS1dcCR4BhfL+zwiQ3CuzyAy4x23tr+VkzjE=; b=pr56FUr28WzVjlye8ocfuUATkeSwhUXvbjPgGkEbab2FCVC+0BKyl8PhOHOFpR/zRWD2YJ XkENxEAzZ+xaNySUfCCAfperdR1yK017PGgjlx8BHtiTSBrVceVD6B+fvb12QX9yuBiWP6 UV9FaMEAQthXh0P6zC/B1D/pMFgxjZ8= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 981CFB2AE; Tue, 29 Sep 2020 08:20:09 +0000 (UTC) Date: Tue, 29 Sep 2020 10:20:08 +0200 From: Michal Hocko To: Daniel Vetter Cc: "Paul E. McKenney" , Juri Lelli , Peter Zijlstra , Sebastian Andrzej Siewior , Lai Jiangshan , dri-devel , Ben Segall , Linux-MM , "open list:KERNEL SELFTEST FRAMEWORK" , linux-hexagon@vger.kernel.org, Will Deacon , Ingo Molnar , Anton Ivanov , linux-arch , Vincent Guittot , Herbert Xu , Brian Cain , Richard Weinberger , Russell King , Ard Biesheuvel , David Airlie , Ingo Molnar , Geert Uytterhoeven , Mel Gorman , intel-gfx , Matt Turner , Valentin Schneider , linux-xtensa@linux-xtensa.org, Shuah Khan , Jeff Dike , linux-um , Josh Triplett , Steven Rostedt , rcu@vger.kernel.org, linux-m68k , Ivan Kokshaysky , Rodrigo Vivi , Thomas Gleixner , Dietmar Eggemann , Linux ARM , Richard Henderson , Chris Zankel , Max Filippov , Daniel Bristot de Oliveira , LKML , alpha , Mathieu Desnoyers , Andrew Morton , Linus Torvalds Subject: Re: [patch 00/13] preempt: Make preempt count unconditional Message-ID: <20200929081938.GC22035@dhcp22.suse.cz> References: <871rj4owfn.fsf@nanos.tec.linutronix.de> <87bli75t7v.fsf@nanos.tec.linutronix.de> <20200916152956.GV29330@paulmck-ThinkPad-P72> <20200916205840.GD29330@paulmck-ThinkPad-P72> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Message-ID: <20200929082008.0CepXhTdkl6GfzQ93hf1QTlMI9OuZ-SW-BUabtPDoP4@z> On Wed 16-09-20 23:43:02, Daniel Vetter wrote: > I can > then figure out whether it's better to risk not spotting issues with > call_rcu vs slapping a memalloc_noio_save/restore around all these > critical section which force-degrades any allocation to GFP_ATOMIC at did you mean memalloc_noreclaim_* here? > most, but has the risk that we run into code that assumes "GFP_KERNEL > never fails for small stuff" and has a decidedly less tested fallback > path than rcu code. Even if the above then please note that memalloc_noreclaim_* or PF_MEMALLOC should be used with an extreme care. Essentially only for internal memory reclaimers. It grants access to _all_ the available memory so any abuse can be detrimental to the overall system operation. Allocation failure in this mode means that we are out of memory and any code relying on such an allocation has to carefuly consider failure. This is not a random allocation mode. -- Michal Hocko SUSE Labs 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=-5.4 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 7054BC4741F for ; Tue, 29 Sep 2020 08:21:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1A4FC20739 for ; Tue, 29 Sep 2020 08:21:28 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=suse.com header.i=@suse.com header.b="kYjuvZ+i" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727783AbgI2IV1 (ORCPT ); Tue, 29 Sep 2020 04:21:27 -0400 Received: from mx2.suse.de ([195.135.220.15]:33218 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727653AbgI2IVY (ORCPT ); Tue, 29 Sep 2020 04:21:24 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1601367682; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=KFyfyEQCS1dcCR4BhfL+zwiQ3CuzyAy4x23tr+VkzjE=; b=kYjuvZ+ilRICWeNF3tv+sX4B6qR0l26SNFX+2yuqmAbG6VZsVdy+/ab4DWFA/2mAPMzvho sWiMi4hR4DtnoNBd3zA9aScladT2LR3g7zk3zp4xXinjBQFShKRtNv5abZ+aKM+mJdoLfs LfJPGyvdVLHOxuKwI+4KWXzshc3e4XY= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 4162CACA3; Tue, 29 Sep 2020 08:21:22 +0000 (UTC) Date: Tue, 29 Sep 2020 10:21:21 +0200 From: Michal Hocko To: Daniel Vetter Cc: "Paul E. McKenney" , Juri Lelli , Peter Zijlstra , Sebastian Andrzej Siewior , Lai Jiangshan , dri-devel , Ben Segall , Linux-MM , "open list:KERNEL SELFTEST FRAMEWORK" , linux-hexagon@vger.kernel.org, Will Deacon , Ingo Molnar , Anton Ivanov , linux-arch , Vincent Guittot , Herbert Xu , Brian Cain , Richard Weinberger , Russell King , Ard Biesheuvel , David Airlie , Ingo Molnar , Geert Uytterhoeven , Mel Gorman , intel-gfx , Matt Turner , Valentin Schneider , linux-xtensa@linux-xtensa.org, Shuah Khan , Jeff Dike , linux-um , Josh Triplett , Steven Rostedt , rcu@vger.kernel.org, linux-m68k , Ivan Kokshaysky , Rodrigo Vivi , Thomas Gleixner , Dietmar Eggemann , Linux ARM , Richard Henderson , Chris Zankel , Max Filippov , Daniel Bristot de Oliveira , LKML , alpha , Mathieu Desnoyers , Andrew Morton , Linus Torvalds Subject: Re: [patch 00/13] preempt: Make preempt count unconditional Message-ID: <20200929081938.GC22035@dhcp22.suse.cz> References: <871rj4owfn.fsf@nanos.tec.linutronix.de> <87bli75t7v.fsf@nanos.tec.linutronix.de> <20200916152956.GV29330@paulmck-ThinkPad-P72> <20200916205840.GD29330@paulmck-ThinkPad-P72> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Message-ID: <20200929082121.l4gss6SIN9tyRe6VEIsJWTGiayhPkJ0y8Z3Y42P4wCU@z> On Wed 16-09-20 23:43:02, Daniel Vetter wrote: > I can > then figure out whether it's better to risk not spotting issues with > call_rcu vs slapping a memalloc_noio_save/restore around all these > critical section which force-degrades any allocation to GFP_ATOMIC at did you mean memalloc_noreclaim_* here? > most, but has the risk that we run into code that assumes "GFP_KERNEL > never fails for small stuff" and has a decidedly less tested fallback > path than rcu code. Even if the above then please note that memalloc_noreclaim_* or PF_MEMALLOC should be used with an extreme care. Essentially only for internal memory reclaimers. It grants access to _all_ the available memory so any abuse can be detrimental to the overall system operation. Allocation failure in this mode means that we are out of memory and any code relying on such an allocation has to carefuly consider failure. This is not a random allocation mode. -- Michal Hocko SUSE Labs 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=-5.4 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 1A40BC4346E for ; Tue, 29 Sep 2020 08:23:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C087120773 for ; Tue, 29 Sep 2020 08:23:29 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=suse.com header.i=@suse.com header.b="Yx+4OiWz" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727714AbgI2IX3 (ORCPT ); Tue, 29 Sep 2020 04:23:29 -0400 Received: from mx2.suse.de ([195.135.220.15]:34326 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727484AbgI2IX1 (ORCPT ); Tue, 29 Sep 2020 04:23:27 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1601367805; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=KFyfyEQCS1dcCR4BhfL+zwiQ3CuzyAy4x23tr+VkzjE=; b=Yx+4OiWzh8hL3oRWBVwsl7OoNxopUmSyQasLhmn1G1pwm5WeUKovPN8LH2bdOC7Tf1qJAG BQKht+ljEQ7JSXztBWuZ/SDej3VcAwduMW5YketNY8WVwtpxMMor30Pmo+P2rpxR7SkCAG TBCtVCqjpOLjck1NyY3qWCFDobpueAs= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 0860EB2A1; Tue, 29 Sep 2020 08:23:25 +0000 (UTC) Date: Tue, 29 Sep 2020 10:23:24 +0200 From: Michal Hocko To: Daniel Vetter Cc: "Paul E. McKenney" , Juri Lelli , Peter Zijlstra , Sebastian Andrzej Siewior , Lai Jiangshan , dri-devel , Ben Segall , Linux-MM , "open list:KERNEL SELFTEST FRAMEWORK" , linux-hexagon@vger.kernel.org, Will Deacon , Ingo Molnar , Anton Ivanov , linux-arch , Vincent Guittot , Herbert Xu , Brian Cain , Richard Weinberger , Russell King , Ard Biesheuvel , David Airlie , Ingo Molnar , Geert Uytterhoeven , Mel Gorman , intel-gfx , Matt Turner , Valentin Schneider , linux-xtensa@linux-xtensa.org, Shuah Khan , Jeff Dike , linux-um , Josh Triplett , Steven Rostedt , rcu@vger.kernel.org, linux-m68k , Ivan Kokshaysky , Rodrigo Vivi , Thomas Gleixner , Dietmar Eggemann , Linux ARM , Richard Henderson , Chris Zankel , Max Filippov , Daniel Bristot de Oliveira , LKML , alpha , Mathieu Desnoyers , Andrew Morton , Linus Torvalds Subject: Re: [patch 00/13] preempt: Make preempt count unconditional Message-ID: <20200929081938.GC22035@dhcp22.suse.cz> References: <871rj4owfn.fsf@nanos.tec.linutronix.de> <87bli75t7v.fsf@nanos.tec.linutronix.de> <20200916152956.GV29330@paulmck-ThinkPad-P72> <20200916205840.GD29330@paulmck-ThinkPad-P72> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Message-ID: <20200929082324.IfBCDP-BI_B906MQEiFkwrr4j-EOgQCBoui4OohKmGc@z> On Wed 16-09-20 23:43:02, Daniel Vetter wrote: > I can > then figure out whether it's better to risk not spotting issues with > call_rcu vs slapping a memalloc_noio_save/restore around all these > critical section which force-degrades any allocation to GFP_ATOMIC at did you mean memalloc_noreclaim_* here? > most, but has the risk that we run into code that assumes "GFP_KERNEL > never fails for small stuff" and has a decidedly less tested fallback > path than rcu code. Even if the above then please note that memalloc_noreclaim_* or PF_MEMALLOC should be used with an extreme care. Essentially only for internal memory reclaimers. It grants access to _all_ the available memory so any abuse can be detrimental to the overall system operation. Allocation failure in this mode means that we are out of memory and any code relying on such an allocation has to carefuly consider failure. This is not a random allocation mode. -- Michal Hocko SUSE Labs 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=-3.9 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS 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 49537C4727F for ; Tue, 29 Sep 2020 08:19:46 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 8F67920773 for ; Tue, 29 Sep 2020 08:19:45 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=suse.com header.i=@suse.com header.b="SSpMjosS" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8F67920773 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=suse.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id C09896B005C; Tue, 29 Sep 2020 04:19:44 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id BBA8C6B005D; Tue, 29 Sep 2020 04:19:44 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id A823E6B0062; Tue, 29 Sep 2020 04:19:44 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0153.hostedemail.com [216.40.44.153]) by kanga.kvack.org (Postfix) with ESMTP id 910FD6B005C for ; Tue, 29 Sep 2020 04:19:44 -0400 (EDT) Received: from smtpin04.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 494433659 for ; Tue, 29 Sep 2020 08:19:44 +0000 (UTC) X-FDA: 77315400288.04.ghost20_0b0d20a27188 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin04.hostedemail.com (Postfix) with ESMTP id 21AE5800EFA3 for ; Tue, 29 Sep 2020 08:19:44 +0000 (UTC) X-HE-Tag: ghost20_0b0d20a27188 X-Filterd-Recvd-Size: 4929 Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) by imf06.hostedemail.com (Postfix) with ESMTP for ; Tue, 29 Sep 2020 08:19:43 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1601367582; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=KFyfyEQCS1dcCR4BhfL+zwiQ3CuzyAy4x23tr+VkzjE=; b=SSpMjosSL8o4OPVa55QL9wIlM8PHwJpdBy+0T8Zs2+GxBxG6YA9l00PJ9Y66qcHmMfGLv9 u+g+tcEvJ7RxAvAP57LRStfEelxtPsdHOGOgFzbQCNh9qQZDiKdnSarvXzcr1YnPqWmMjI wdLRjalKNBbwgyGfH1Q3bT+vgMo4axA= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 3E86BADD8; Tue, 29 Sep 2020 08:19:42 +0000 (UTC) Date: Tue, 29 Sep 2020 10:19:38 +0200 From: Michal Hocko To: Daniel Vetter Cc: "Paul E. McKenney" , Juri Lelli , Peter Zijlstra , Sebastian Andrzej Siewior , Lai Jiangshan , dri-devel , Ben Segall , Linux-MM , "open list:KERNEL SELFTEST FRAMEWORK" , linux-hexagon@vger.kernel.org, Will Deacon , Ingo Molnar , Anton Ivanov , linux-arch , Vincent Guittot , Herbert Xu , Brian Cain , Richard Weinberger , Russell King , Ard Biesheuvel , David Airlie , Ingo Molnar , Geert Uytterhoeven , Mel Gorman , intel-gfx , Matt Turner , Valentin Schneider , linux-xtensa@linux-xtensa.org, Shuah Khan , Jeff Dike , linux-um , Josh Triplett , Steven Rostedt , rcu@vger.kernel.org, linux-m68k , Ivan Kokshaysky , Rodrigo Vivi , Thomas Gleixner , Dietmar Eggemann , Linux ARM , Richard Henderson , Chris Zankel , Max Filippov , Daniel Bristot de Oliveira , LKML , alpha , Mathieu Desnoyers , Andrew Morton , Linus Torvalds Subject: Re: [patch 00/13] preempt: Make preempt count unconditional Message-ID: <20200929081938.GC22035@dhcp22.suse.cz> References: <871rj4owfn.fsf@nanos.tec.linutronix.de> <87bli75t7v.fsf@nanos.tec.linutronix.de> <20200916152956.GV29330@paulmck-ThinkPad-P72> <20200916205840.GD29330@paulmck-ThinkPad-P72> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: 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 Wed 16-09-20 23:43:02, Daniel Vetter wrote: > I can > then figure out whether it's better to risk not spotting issues with > call_rcu vs slapping a memalloc_noio_save/restore around all these > critical section which force-degrades any allocation to GFP_ATOMIC at did you mean memalloc_noreclaim_* here? > most, but has the risk that we run into code that assumes "GFP_KERNEL > never fails for small stuff" and has a decidedly less tested fallback > path than rcu code. Even if the above then please note that memalloc_noreclaim_* or PF_MEMALLOC should be used with an extreme care. Essentially only for internal memory reclaimers. It grants access to _all_ the available memory so any abuse can be detrimental to the overall system operation. Allocation failure in this mode means that we are out of memory and any code relying on such an allocation has to carefuly consider failure. This is not a random allocation mode. -- Michal Hocko SUSE Labs 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=-3.9 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS 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 7DA50C4727F for ; Tue, 29 Sep 2020 08:19:52 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id E948B20897 for ; Tue, 29 Sep 2020 08:19:51 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=suse.com header.i=@suse.com header.b="WFaQTV+k" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E948B20897 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=suse.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 68D256B005D; Tue, 29 Sep 2020 04:19:51 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 63D4D6B0062; Tue, 29 Sep 2020 04:19:51 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 4DD316B0068; Tue, 29 Sep 2020 04:19:51 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0090.hostedemail.com [216.40.44.90]) by kanga.kvack.org (Postfix) with ESMTP id 3032B6B005D for ; Tue, 29 Sep 2020 04:19:51 -0400 (EDT) Received: from smtpin20.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id DDF7B8249980 for ; Tue, 29 Sep 2020 08:19:50 +0000 (UTC) X-FDA: 77315400540.20.patch38_500617027188 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin20.hostedemail.com (Postfix) with ESMTP id AD102180C07AB for ; Tue, 29 Sep 2020 08:19:50 +0000 (UTC) X-HE-Tag: patch38_500617027188 X-Filterd-Recvd-Size: 4929 Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) by imf02.hostedemail.com (Postfix) with ESMTP for ; Tue, 29 Sep 2020 08:19:50 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1601367589; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=KFyfyEQCS1dcCR4BhfL+zwiQ3CuzyAy4x23tr+VkzjE=; b=WFaQTV+kmp2Dcf4ETP9+6ZNrPfy9q5pMDECagrCQ3MjluCnYeqMkFTw/YcJHGz2iksDQw9 srvpAmlMUEz2D9SjbkwSKNyTXnnl0c+U97e7qNgFVE9O8k3lMFBfs0YlvFJAzRLJyf+n+C wZ5d1Zkp/fxHdHhoVK5syk5dxSgYigs= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id C7EE3B29F; Tue, 29 Sep 2020 08:19:48 +0000 (UTC) Date: Tue, 29 Sep 2020 10:19:48 +0200 From: Michal Hocko To: Daniel Vetter Cc: "Paul E. McKenney" , Juri Lelli , Peter Zijlstra , Sebastian Andrzej Siewior , Lai Jiangshan , dri-devel , Ben Segall , Linux-MM , "open list:KERNEL SELFTEST FRAMEWORK" , linux-hexagon@vger.kernel.org, Will Deacon , Ingo Molnar , Anton Ivanov , linux-arch , Vincent Guittot , Herbert Xu , Brian Cain , Richard Weinberger , Russell King , Ard Biesheuvel , David Airlie , Ingo Molnar , Geert Uytterhoeven , Mel Gorman , intel-gfx , Matt Turner , Valentin Schneider , linux-xtensa@linux-xtensa.org, Shuah Khan , Jeff Dike , linux-um , Josh Triplett , Steven Rostedt , rcu@vger.kernel.org, linux-m68k , Ivan Kokshaysky , Rodrigo Vivi , Thomas Gleixner , Dietmar Eggemann , Linux ARM , Richard Henderson , Chris Zankel , Max Filippov , Daniel Bristot de Oliveira , LKML , alpha , Mathieu Desnoyers , Andrew Morton , Linus Torvalds Subject: Re: [patch 00/13] preempt: Make preempt count unconditional Message-ID: <20200929081938.GC22035@dhcp22.suse.cz> References: <871rj4owfn.fsf@nanos.tec.linutronix.de> <87bli75t7v.fsf@nanos.tec.linutronix.de> <20200916152956.GV29330@paulmck-ThinkPad-P72> <20200916205840.GD29330@paulmck-ThinkPad-P72> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: 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: Message-ID: <20200929081948.CRFySOrdkvC8cgf8Z0h7iuWlfwz5rDKOKGl0jT2CiUc@z> On Wed 16-09-20 23:43:02, Daniel Vetter wrote: > I can > then figure out whether it's better to risk not spotting issues with > call_rcu vs slapping a memalloc_noio_save/restore around all these > critical section which force-degrades any allocation to GFP_ATOMIC at did you mean memalloc_noreclaim_* here? > most, but has the risk that we run into code that assumes "GFP_KERNEL > never fails for small stuff" and has a decidedly less tested fallback > path than rcu code. Even if the above then please note that memalloc_noreclaim_* or PF_MEMALLOC should be used with an extreme care. Essentially only for internal memory reclaimers. It grants access to _all_ the available memory so any abuse can be detrimental to the overall system operation. Allocation failure in this mode means that we are out of memory and any code relying on such an allocation has to carefuly consider failure. This is not a random allocation mode. -- Michal Hocko SUSE Labs 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=-3.9 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS 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 E3946C4346E for ; Tue, 29 Sep 2020 08:20:12 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 80D70206C1 for ; Tue, 29 Sep 2020 08:20:12 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=suse.com header.i=@suse.com header.b="pr56FUr2" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 80D70206C1 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=suse.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 1F9056B0062; Tue, 29 Sep 2020 04:20:12 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 1A6546B0068; Tue, 29 Sep 2020 04:20:12 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 06F136B006C; Tue, 29 Sep 2020 04:20:12 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0222.hostedemail.com [216.40.44.222]) by kanga.kvack.org (Postfix) with ESMTP id E59E26B0062 for ; Tue, 29 Sep 2020 04:20:11 -0400 (EDT) Received: from smtpin05.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id A94BD180AD801 for ; Tue, 29 Sep 2020 08:20:11 +0000 (UTC) X-FDA: 77315401422.05.eye19_131498d27188 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin05.hostedemail.com (Postfix) with ESMTP id 88B7F18034AD9 for ; Tue, 29 Sep 2020 08:20:11 +0000 (UTC) X-HE-Tag: eye19_131498d27188 X-Filterd-Recvd-Size: 4929 Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) by imf07.hostedemail.com (Postfix) with ESMTP for ; Tue, 29 Sep 2020 08:20:10 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1601367609; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=KFyfyEQCS1dcCR4BhfL+zwiQ3CuzyAy4x23tr+VkzjE=; b=pr56FUr28WzVjlye8ocfuUATkeSwhUXvbjPgGkEbab2FCVC+0BKyl8PhOHOFpR/zRWD2YJ XkENxEAzZ+xaNySUfCCAfperdR1yK017PGgjlx8BHtiTSBrVceVD6B+fvb12QX9yuBiWP6 UV9FaMEAQthXh0P6zC/B1D/pMFgxjZ8= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 981CFB2AE; Tue, 29 Sep 2020 08:20:09 +0000 (UTC) Date: Tue, 29 Sep 2020 10:20:08 +0200 From: Michal Hocko To: Daniel Vetter Cc: "Paul E. McKenney" , Juri Lelli , Peter Zijlstra , Sebastian Andrzej Siewior , Lai Jiangshan , dri-devel , Ben Segall , Linux-MM , "open list:KERNEL SELFTEST FRAMEWORK" , linux-hexagon@vger.kernel.org, Will Deacon , Ingo Molnar , Anton Ivanov , linux-arch , Vincent Guittot , Herbert Xu , Brian Cain , Richard Weinberger , Russell King , Ard Biesheuvel , David Airlie , Ingo Molnar , Geert Uytterhoeven , Mel Gorman , intel-gfx , Matt Turner , Valentin Schneider , linux-xtensa@linux-xtensa.org, Shuah Khan , Jeff Dike , linux-um , Josh Triplett , Steven Rostedt , rcu@vger.kernel.org, linux-m68k , Ivan Kokshaysky , Rodrigo Vivi , Thomas Gleixner , Dietmar Eggemann , Linux ARM , Richard Henderson , Chris Zankel , Max Filippov , Daniel Bristot de Oliveira , LKML , alpha , Mathieu Desnoyers , Andrew Morton , Linus Torvalds Subject: Re: [patch 00/13] preempt: Make preempt count unconditional Message-ID: <20200929081938.GC22035@dhcp22.suse.cz> References: <871rj4owfn.fsf@nanos.tec.linutronix.de> <87bli75t7v.fsf@nanos.tec.linutronix.de> <20200916152956.GV29330@paulmck-ThinkPad-P72> <20200916205840.GD29330@paulmck-ThinkPad-P72> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: 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: Message-ID: <20200929082008.q2hAMZCVHUJcsw1TSHYr9L6EuM3AtnRz-6SGPIXjIgU@z> On Wed 16-09-20 23:43:02, Daniel Vetter wrote: > I can > then figure out whether it's better to risk not spotting issues with > call_rcu vs slapping a memalloc_noio_save/restore around all these > critical section which force-degrades any allocation to GFP_ATOMIC at did you mean memalloc_noreclaim_* here? > most, but has the risk that we run into code that assumes "GFP_KERNEL > never fails for small stuff" and has a decidedly less tested fallback > path than rcu code. Even if the above then please note that memalloc_noreclaim_* or PF_MEMALLOC should be used with an extreme care. Essentially only for internal memory reclaimers. It grants access to _all_ the available memory so any abuse can be detrimental to the overall system operation. Allocation failure in this mode means that we are out of memory and any code relying on such an allocation has to carefuly consider failure. This is not a random allocation mode. -- Michal Hocko SUSE Labs 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=-5.4 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 AAF37C4741F for ; Tue, 29 Sep 2020 08:21:25 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 2FDA220773 for ; Tue, 29 Sep 2020 08:21:25 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=suse.com header.i=@suse.com header.b="kYjuvZ+i" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2FDA220773 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=suse.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id A305D6B005C; Tue, 29 Sep 2020 04:21:24 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 9E1C96B005D; Tue, 29 Sep 2020 04:21:24 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 8F7686B0062; Tue, 29 Sep 2020 04:21:24 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0227.hostedemail.com [216.40.44.227]) by kanga.kvack.org (Postfix) with ESMTP id 7A4546B005C for ; Tue, 29 Sep 2020 04:21:24 -0400 (EDT) Received: from smtpin13.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 38B02249D for ; Tue, 29 Sep 2020 08:21:24 +0000 (UTC) X-FDA: 77315404488.13.bead08_2511e6327188 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin13.hostedemail.com (Postfix) with ESMTP id 128B918140B60 for ; Tue, 29 Sep 2020 08:21:24 +0000 (UTC) X-HE-Tag: bead08_2511e6327188 X-Filterd-Recvd-Size: 4967 Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) by imf12.hostedemail.com (Postfix) with ESMTP for ; Tue, 29 Sep 2020 08:21:23 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1601367682; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=KFyfyEQCS1dcCR4BhfL+zwiQ3CuzyAy4x23tr+VkzjE=; b=kYjuvZ+ilRICWeNF3tv+sX4B6qR0l26SNFX+2yuqmAbG6VZsVdy+/ab4DWFA/2mAPMzvho sWiMi4hR4DtnoNBd3zA9aScladT2LR3g7zk3zp4xXinjBQFShKRtNv5abZ+aKM+mJdoLfs LfJPGyvdVLHOxuKwI+4KWXzshc3e4XY= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 4162CACA3; Tue, 29 Sep 2020 08:21:22 +0000 (UTC) Date: Tue, 29 Sep 2020 10:21:21 +0200 From: Michal Hocko To: Daniel Vetter Cc: "Paul E. McKenney" , Juri Lelli , Peter Zijlstra , Sebastian Andrzej Siewior , Lai Jiangshan , dri-devel , Ben Segall , Linux-MM , "open list:KERNEL SELFTEST FRAMEWORK" , linux-hexagon@vger.kernel.org, Will Deacon , Ingo Molnar , Anton Ivanov , linux-arch , Vincent Guittot , Herbert Xu , Brian Cain , Richard Weinberger , Russell King , Ard Biesheuvel , David Airlie , Ingo Molnar , Geert Uytterhoeven , Mel Gorman , intel-gfx , Matt Turner , Valentin Schneider , linux-xtensa@linux-xtensa.org, Shuah Khan , Jeff Dike , linux-um , Josh Triplett , Steven Rostedt , rcu@vger.kernel.org, linux-m68k , Ivan Kokshaysky , Rodrigo Vivi , Thomas Gleixner , Dietmar Eggemann , Linux ARM , Richard Henderson , Chris Zankel , Max Filippov , Daniel Bristot de Oliveira , LKML , alpha , Mathieu Desnoyers , Andrew Morton , Linus Torvalds Subject: Re: [patch 00/13] preempt: Make preempt count unconditional Message-ID: <20200929081938.GC22035@dhcp22.suse.cz> References: <871rj4owfn.fsf@nanos.tec.linutronix.de> <87bli75t7v.fsf@nanos.tec.linutronix.de> <20200916152956.GV29330@paulmck-ThinkPad-P72> <20200916205840.GD29330@paulmck-ThinkPad-P72> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) 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: Message-ID: <20200929082121.BWnstl-CR-LYSsV_6VdJqqaVKq3gmj4qJQyQY-nMvpk@z> On Wed 16-09-20 23:43:02, Daniel Vetter wrote: > I can > then figure out whether it's better to risk not spotting issues with > call_rcu vs slapping a memalloc_noio_save/restore around all these > critical section which force-degrades any allocation to GFP_ATOMIC at did you mean memalloc_noreclaim_* here? > most, but has the risk that we run into code that assumes "GFP_KERNEL > never fails for small stuff" and has a decidedly less tested fallback > path than rcu code. Even if the above then please note that memalloc_noreclaim_* or PF_MEMALLOC should be used with an extreme care. Essentially only for internal memory reclaimers. It grants access to _all_ the available memory so any abuse can be detrimental to the overall system operation. Allocation failure in this mode means that we are out of memory and any code relying on such an allocation has to carefuly consider failure. This is not a random allocation mode. -- Michal Hocko SUSE Labs 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=-5.4 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 AA7A3C47420 for ; Tue, 29 Sep 2020 08:23:28 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 41F3820897 for ; Tue, 29 Sep 2020 08:23:28 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=suse.com header.i=@suse.com header.b="Yx+4OiWz" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 41F3820897 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=suse.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 71E516B005C; Tue, 29 Sep 2020 04:23:27 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 6A6D76B005D; Tue, 29 Sep 2020 04:23:27 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 5707F6B0062; Tue, 29 Sep 2020 04:23:27 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0112.hostedemail.com [216.40.44.112]) by kanga.kvack.org (Postfix) with ESMTP id 3B87D6B005C for ; Tue, 29 Sep 2020 04:23:27 -0400 (EDT) Received: from smtpin01.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id F146B4DCB for ; Tue, 29 Sep 2020 08:23:26 +0000 (UTC) X-FDA: 77315409612.01.point91_480558e27188 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin01.hostedemail.com (Postfix) with ESMTP id D336610045ECD for ; Tue, 29 Sep 2020 08:23:26 +0000 (UTC) X-HE-Tag: point91_480558e27188 X-Filterd-Recvd-Size: 4967 Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) by imf25.hostedemail.com (Postfix) with ESMTP for ; Tue, 29 Sep 2020 08:23:26 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1601367805; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=KFyfyEQCS1dcCR4BhfL+zwiQ3CuzyAy4x23tr+VkzjE=; b=Yx+4OiWzh8hL3oRWBVwsl7OoNxopUmSyQasLhmn1G1pwm5WeUKovPN8LH2bdOC7Tf1qJAG BQKht+ljEQ7JSXztBWuZ/SDej3VcAwduMW5YketNY8WVwtpxMMor30Pmo+P2rpxR7SkCAG TBCtVCqjpOLjck1NyY3qWCFDobpueAs= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 0860EB2A1; Tue, 29 Sep 2020 08:23:25 +0000 (UTC) Date: Tue, 29 Sep 2020 10:23:24 +0200 From: Michal Hocko To: Daniel Vetter Cc: "Paul E. McKenney" , Juri Lelli , Peter Zijlstra , Sebastian Andrzej Siewior , Lai Jiangshan , dri-devel , Ben Segall , Linux-MM , "open list:KERNEL SELFTEST FRAMEWORK" , linux-hexagon@vger.kernel.org, Will Deacon , Ingo Molnar , Anton Ivanov , linux-arch , Vincent Guittot , Herbert Xu , Brian Cain , Richard Weinberger , Russell King , Ard Biesheuvel , David Airlie , Ingo Molnar , Geert Uytterhoeven , Mel Gorman , intel-gfx , Matt Turner , Valentin Schneider , linux-xtensa@linux-xtensa.org, Shuah Khan , Jeff Dike , linux-um , Josh Triplett , Steven Rostedt , rcu@vger.kernel.org, linux-m68k , Ivan Kokshaysky , Rodrigo Vivi , Thomas Gleixner , Dietmar Eggemann , Linux ARM , Richard Henderson , Chris Zankel , Max Filippov , Daniel Bristot de Oliveira , LKML , alpha , Mathieu Desnoyers , Andrew Morton , Linus Torvalds Subject: Re: [patch 00/13] preempt: Make preempt count unconditional Message-ID: <20200929081938.GC22035@dhcp22.suse.cz> References: <871rj4owfn.fsf@nanos.tec.linutronix.de> <87bli75t7v.fsf@nanos.tec.linutronix.de> <20200916152956.GV29330@paulmck-ThinkPad-P72> <20200916205840.GD29330@paulmck-ThinkPad-P72> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) 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: Message-ID: <20200929082324.kx5jvSUSkzNk893oa2yw1MUbVTjsZpS38CX9H3ggbMU@z> On Wed 16-09-20 23:43:02, Daniel Vetter wrote: > I can > then figure out whether it's better to risk not spotting issues with > call_rcu vs slapping a memalloc_noio_save/restore around all these > critical section which force-degrades any allocation to GFP_ATOMIC at did you mean memalloc_noreclaim_* here? > most, but has the risk that we run into code that assumes "GFP_KERNEL > never fails for small stuff" and has a decidedly less tested fallback > path than rcu code. Even if the above then please note that memalloc_noreclaim_* or PF_MEMALLOC should be used with an extreme care. Essentially only for internal memory reclaimers. It grants access to _all_ the available memory so any abuse can be detrimental to the overall system operation. Allocation failure in this mode means that we are out of memory and any code relying on such an allocation has to carefuly consider failure. This is not a random allocation mode. -- Michal Hocko SUSE Labs 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,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 9DE6EC2D0A8 for ; Wed, 30 Sep 2020 07:50:22 +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 25CF62075F for ; Wed, 30 Sep 2020 07:50:22 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=suse.com header.i=@suse.com header.b="WFaQTV+k" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 25CF62075F Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=suse.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 0D213898BF; Wed, 30 Sep 2020 07:50:11 +0000 (UTC) Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) by gabe.freedesktop.org (Postfix) with ESMTPS id 4F06B89B05; Tue, 29 Sep 2020 08:19:50 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1601367589; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=KFyfyEQCS1dcCR4BhfL+zwiQ3CuzyAy4x23tr+VkzjE=; b=WFaQTV+kmp2Dcf4ETP9+6ZNrPfy9q5pMDECagrCQ3MjluCnYeqMkFTw/YcJHGz2iksDQw9 srvpAmlMUEz2D9SjbkwSKNyTXnnl0c+U97e7qNgFVE9O8k3lMFBfs0YlvFJAzRLJyf+n+C wZ5d1Zkp/fxHdHhoVK5syk5dxSgYigs= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id C7EE3B29F; Tue, 29 Sep 2020 08:19:48 +0000 (UTC) Date: Tue, 29 Sep 2020 10:19:48 +0200 From: Michal Hocko To: Daniel Vetter Subject: Re: [patch 00/13] preempt: Make preempt count unconditional Message-ID: <20200929081938.GC22035@dhcp22.suse.cz> References: <871rj4owfn.fsf@nanos.tec.linutronix.de> <87bli75t7v.fsf@nanos.tec.linutronix.de> <20200916152956.GV29330@paulmck-ThinkPad-P72> <20200916205840.GD29330@paulmck-ThinkPad-P72> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-Mailman-Approved-At: Wed, 30 Sep 2020 07:50:09 +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: Juri Lelli , Peter Zijlstra , Sebastian Andrzej Siewior , Lai Jiangshan , dri-devel , Ben Segall , Linux-MM , "open list:KERNEL SELFTEST FRAMEWORK" , Will Deacon , Ard Biesheuvel , Anton Ivanov , linux-arch , Vincent Guittot , Herbert Xu , Brian Cain , linux-hexagon@vger.kernel.org, Russell King , Ingo Molnar , David Airlie , Ingo Molnar , Geert Uytterhoeven , Mel Gorman , Matt Turner , Valentin Schneider , linux-xtensa@linux-xtensa.org, Shuah Khan , "Paul E. McKenney" , Jeff Dike , intel-gfx , alpha , linux-um , Josh Triplett , Steven Rostedt , rcu@vger.kernel.org, linux-m68k , Ivan Kokshaysky , Rodrigo Vivi , Thomas Gleixner , Dietmar Eggemann , Linux ARM , Richard Henderson , Chris Zankel , Max Filippov , Linus Torvalds , LKML , Richard Weinberger , Mathieu Desnoyers , Andrew Morton , Daniel Bristot de Oliveira Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" On Wed 16-09-20 23:43:02, Daniel Vetter wrote: > I can > then figure out whether it's better to risk not spotting issues with > call_rcu vs slapping a memalloc_noio_save/restore around all these > critical section which force-degrades any allocation to GFP_ATOMIC at did you mean memalloc_noreclaim_* here? > most, but has the risk that we run into code that assumes "GFP_KERNEL > never fails for small stuff" and has a decidedly less tested fallback > path than rcu code. Even if the above then please note that memalloc_noreclaim_* or PF_MEMALLOC should be used with an extreme care. Essentially only for internal memory reclaimers. It grants access to _all_ the available memory so any abuse can be detrimental to the overall system operation. Allocation failure in this mode means that we are out of memory and any code relying on such an allocation has to carefuly consider failure. This is not a random allocation mode. -- Michal Hocko SUSE Labs _______________________________________________ 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=-5.3 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 51848C4727F for ; Wed, 30 Sep 2020 07:50:50 +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 04494204FD for ; Wed, 30 Sep 2020 07:50:49 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=suse.com header.i=@suse.com header.b="kYjuvZ+i" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 04494204FD Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=suse.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 340BD6E4F1; Wed, 30 Sep 2020 07:50:43 +0000 (UTC) Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) by gabe.freedesktop.org (Postfix) with ESMTPS id B218689C2C; Tue, 29 Sep 2020 08:21:23 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1601367682; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=KFyfyEQCS1dcCR4BhfL+zwiQ3CuzyAy4x23tr+VkzjE=; b=kYjuvZ+ilRICWeNF3tv+sX4B6qR0l26SNFX+2yuqmAbG6VZsVdy+/ab4DWFA/2mAPMzvho sWiMi4hR4DtnoNBd3zA9aScladT2LR3g7zk3zp4xXinjBQFShKRtNv5abZ+aKM+mJdoLfs LfJPGyvdVLHOxuKwI+4KWXzshc3e4XY= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 4162CACA3; Tue, 29 Sep 2020 08:21:22 +0000 (UTC) Date: Tue, 29 Sep 2020 10:21:21 +0200 From: Michal Hocko To: Daniel Vetter Subject: Re: [patch 00/13] preempt: Make preempt count unconditional Message-ID: <20200929081938.GC22035@dhcp22.suse.cz> References: <871rj4owfn.fsf@nanos.tec.linutronix.de> <87bli75t7v.fsf@nanos.tec.linutronix.de> <20200916152956.GV29330@paulmck-ThinkPad-P72> <20200916205840.GD29330@paulmck-ThinkPad-P72> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) X-Mailman-Approved-At: Wed, 30 Sep 2020 07:50:09 +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: Juri Lelli , Peter Zijlstra , Sebastian Andrzej Siewior , Lai Jiangshan , dri-devel , Ben Segall , Linux-MM , "open list:KERNEL SELFTEST FRAMEWORK" , Will Deacon , Ard Biesheuvel , Anton Ivanov , linux-arch , Vincent Guittot , Herbert Xu , Brian Cain , linux-hexagon@vger.kernel.org, Russell King , Ingo Molnar , David Airlie , Ingo Molnar , Geert Uytterhoeven , Mel Gorman , Matt Turner , Valentin Schneider , linux-xtensa@linux-xtensa.org, Shuah Khan , "Paul E. McKenney" , Jeff Dike , intel-gfx , alpha , linux-um , Josh Triplett , Steven Rostedt , rcu@vger.kernel.org, linux-m68k , Ivan Kokshaysky , Rodrigo Vivi , Thomas Gleixner , Dietmar Eggemann , Linux ARM , Richard Henderson , Chris Zankel , Max Filippov , Linus Torvalds , LKML , Richard Weinberger , Mathieu Desnoyers , Andrew Morton , Daniel Bristot de Oliveira Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" Message-ID: <20200929082121.AayUL6cmM91WqadoeAIRDWRav6rKHqZ3AFoCCVimq9I@z> On Wed 16-09-20 23:43:02, Daniel Vetter wrote: > I can > then figure out whether it's better to risk not spotting issues with > call_rcu vs slapping a memalloc_noio_save/restore around all these > critical section which force-degrades any allocation to GFP_ATOMIC at did you mean memalloc_noreclaim_* here? > most, but has the risk that we run into code that assumes "GFP_KERNEL > never fails for small stuff" and has a decidedly less tested fallback > path than rcu code. Even if the above then please note that memalloc_noreclaim_* or PF_MEMALLOC should be used with an extreme care. Essentially only for internal memory reclaimers. It grants access to _all_ the available memory so any abuse can be detrimental to the overall system operation. Allocation failure in this mode means that we are out of memory and any code relying on such an allocation has to carefuly consider failure. This is not a random allocation mode. -- Michal Hocko SUSE Labs _______________________________________________ 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=-3.8 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 CA283C4727F for ; Wed, 30 Sep 2020 07:51:01 +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 72B3A2071E for ; Wed, 30 Sep 2020 07:51:01 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=suse.com header.i=@suse.com header.b="pr56FUr2" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 72B3A2071E Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=suse.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 C614B6E560; Wed, 30 Sep 2020 07:50:54 +0000 (UTC) Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) by gabe.freedesktop.org (Postfix) with ESMTPS id 346AF89AF3; Tue, 29 Sep 2020 08:20:11 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1601367609; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=KFyfyEQCS1dcCR4BhfL+zwiQ3CuzyAy4x23tr+VkzjE=; b=pr56FUr28WzVjlye8ocfuUATkeSwhUXvbjPgGkEbab2FCVC+0BKyl8PhOHOFpR/zRWD2YJ XkENxEAzZ+xaNySUfCCAfperdR1yK017PGgjlx8BHtiTSBrVceVD6B+fvb12QX9yuBiWP6 UV9FaMEAQthXh0P6zC/B1D/pMFgxjZ8= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 981CFB2AE; Tue, 29 Sep 2020 08:20:09 +0000 (UTC) Date: Tue, 29 Sep 2020 10:20:08 +0200 From: Michal Hocko To: Daniel Vetter Subject: Re: [patch 00/13] preempt: Make preempt count unconditional Message-ID: <20200929081938.GC22035@dhcp22.suse.cz> References: <871rj4owfn.fsf@nanos.tec.linutronix.de> <87bli75t7v.fsf@nanos.tec.linutronix.de> <20200916152956.GV29330@paulmck-ThinkPad-P72> <20200916205840.GD29330@paulmck-ThinkPad-P72> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-Mailman-Approved-At: Wed, 30 Sep 2020 07:50:09 +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: Juri Lelli , Peter Zijlstra , Sebastian Andrzej Siewior , Lai Jiangshan , dri-devel , Ben Segall , Linux-MM , "open list:KERNEL SELFTEST FRAMEWORK" , Will Deacon , Ard Biesheuvel , Anton Ivanov , linux-arch , Vincent Guittot , Herbert Xu , Brian Cain , linux-hexagon@vger.kernel.org, Russell King , Ingo Molnar , David Airlie , Ingo Molnar , Geert Uytterhoeven , Mel Gorman , Matt Turner , Valentin Schneider , linux-xtensa@linux-xtensa.org, Shuah Khan , "Paul E. McKenney" , Jeff Dike , intel-gfx , alpha , linux-um , Josh Triplett , Steven Rostedt , rcu@vger.kernel.org, linux-m68k , Ivan Kokshaysky , Rodrigo Vivi , Thomas Gleixner , Dietmar Eggemann , Linux ARM , Richard Henderson , Chris Zankel , Max Filippov , Linus Torvalds , LKML , Richard Weinberger , Mathieu Desnoyers , Andrew Morton , Daniel Bristot de Oliveira Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" Message-ID: <20200929082008.qpa3vl3lFuGVNZ-42dzF_YPLDO3Qcxr2qJsQJ7fYXVU@z> On Wed 16-09-20 23:43:02, Daniel Vetter wrote: > I can > then figure out whether it's better to risk not spotting issues with > call_rcu vs slapping a memalloc_noio_save/restore around all these > critical section which force-degrades any allocation to GFP_ATOMIC at did you mean memalloc_noreclaim_* here? > most, but has the risk that we run into code that assumes "GFP_KERNEL > never fails for small stuff" and has a decidedly less tested fallback > path than rcu code. Even if the above then please note that memalloc_noreclaim_* or PF_MEMALLOC should be used with an extreme care. Essentially only for internal memory reclaimers. It grants access to _all_ the available memory so any abuse can be detrimental to the overall system operation. Allocation failure in this mode means that we are out of memory and any code relying on such an allocation has to carefuly consider failure. This is not a random allocation mode. -- Michal Hocko SUSE Labs _______________________________________________ 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=-3.8 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 5BF53C4727C for ; Wed, 30 Sep 2020 07:51:04 +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 0284C2075F for ; Wed, 30 Sep 2020 07:51:03 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=suse.com header.i=@suse.com header.b="SSpMjosS" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0284C2075F Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=suse.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 4351F6E542; Wed, 30 Sep 2020 07:50:55 +0000 (UTC) Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) by gabe.freedesktop.org (Postfix) with ESMTPS id B569989996; Tue, 29 Sep 2020 08:19:43 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1601367582; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=KFyfyEQCS1dcCR4BhfL+zwiQ3CuzyAy4x23tr+VkzjE=; b=SSpMjosSL8o4OPVa55QL9wIlM8PHwJpdBy+0T8Zs2+GxBxG6YA9l00PJ9Y66qcHmMfGLv9 u+g+tcEvJ7RxAvAP57LRStfEelxtPsdHOGOgFzbQCNh9qQZDiKdnSarvXzcr1YnPqWmMjI wdLRjalKNBbwgyGfH1Q3bT+vgMo4axA= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 3E86BADD8; Tue, 29 Sep 2020 08:19:42 +0000 (UTC) Date: Tue, 29 Sep 2020 10:19:38 +0200 From: Michal Hocko To: Daniel Vetter Subject: Re: [patch 00/13] preempt: Make preempt count unconditional Message-ID: <20200929081938.GC22035@dhcp22.suse.cz> References: <871rj4owfn.fsf@nanos.tec.linutronix.de> <87bli75t7v.fsf@nanos.tec.linutronix.de> <20200916152956.GV29330@paulmck-ThinkPad-P72> <20200916205840.GD29330@paulmck-ThinkPad-P72> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-Mailman-Approved-At: Wed, 30 Sep 2020 07:50:09 +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: Juri Lelli , Peter Zijlstra , Sebastian Andrzej Siewior , Lai Jiangshan , dri-devel , Ben Segall , Linux-MM , "open list:KERNEL SELFTEST FRAMEWORK" , Will Deacon , Ard Biesheuvel , Anton Ivanov , linux-arch , Vincent Guittot , Herbert Xu , Brian Cain , linux-hexagon@vger.kernel.org, Russell King , Ingo Molnar , David Airlie , Ingo Molnar , Geert Uytterhoeven , Mel Gorman , Matt Turner , Valentin Schneider , linux-xtensa@linux-xtensa.org, Shuah Khan , "Paul E. McKenney" , Jeff Dike , intel-gfx , alpha , linux-um , Josh Triplett , Steven Rostedt , rcu@vger.kernel.org, linux-m68k , Ivan Kokshaysky , Rodrigo Vivi , Thomas Gleixner , Dietmar Eggemann , Linux ARM , Richard Henderson , Chris Zankel , Max Filippov , Linus Torvalds , LKML , Richard Weinberger , Mathieu Desnoyers , Andrew Morton , Daniel Bristot de Oliveira Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" Message-ID: <20200929081938.cbyJdX6O6NTJ9ZMmF8AHaiBljYVpkqPkpy55EWseFFw@z> On Wed 16-09-20 23:43:02, Daniel Vetter wrote: > I can > then figure out whether it's better to risk not spotting issues with > call_rcu vs slapping a memalloc_noio_save/restore around all these > critical section which force-degrades any allocation to GFP_ATOMIC at did you mean memalloc_noreclaim_* here? > most, but has the risk that we run into code that assumes "GFP_KERNEL > never fails for small stuff" and has a decidedly less tested fallback > path than rcu code. Even if the above then please note that memalloc_noreclaim_* or PF_MEMALLOC should be used with an extreme care. Essentially only for internal memory reclaimers. It grants access to _all_ the available memory so any abuse can be detrimental to the overall system operation. Allocation failure in this mode means that we are out of memory and any code relying on such an allocation has to carefuly consider failure. This is not a random allocation mode. -- Michal Hocko SUSE Labs _______________________________________________ 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=-5.3 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 67671C2D0A8 for ; Wed, 30 Sep 2020 07:52:05 +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 F0F8A2075F for ; Wed, 30 Sep 2020 07:52:04 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=suse.com header.i=@suse.com header.b="Yx+4OiWz" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org F0F8A2075F Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=suse.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 203C26E56D; Wed, 30 Sep 2020 07:52:04 +0000 (UTC) Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) by gabe.freedesktop.org (Postfix) with ESMTPS id 83D7189C3B; Tue, 29 Sep 2020 08:23:26 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1601367805; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=KFyfyEQCS1dcCR4BhfL+zwiQ3CuzyAy4x23tr+VkzjE=; b=Yx+4OiWzh8hL3oRWBVwsl7OoNxopUmSyQasLhmn1G1pwm5WeUKovPN8LH2bdOC7Tf1qJAG BQKht+ljEQ7JSXztBWuZ/SDej3VcAwduMW5YketNY8WVwtpxMMor30Pmo+P2rpxR7SkCAG TBCtVCqjpOLjck1NyY3qWCFDobpueAs= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 0860EB2A1; Tue, 29 Sep 2020 08:23:25 +0000 (UTC) Date: Tue, 29 Sep 2020 10:23:24 +0200 From: Michal Hocko To: Daniel Vetter Subject: Re: [patch 00/13] preempt: Make preempt count unconditional Message-ID: <20200929081938.GC22035@dhcp22.suse.cz> References: <871rj4owfn.fsf@nanos.tec.linutronix.de> <87bli75t7v.fsf@nanos.tec.linutronix.de> <20200916152956.GV29330@paulmck-ThinkPad-P72> <20200916205840.GD29330@paulmck-ThinkPad-P72> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) X-Mailman-Approved-At: Wed, 30 Sep 2020 07:50:09 +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: Juri Lelli , Peter Zijlstra , Sebastian Andrzej Siewior , Lai Jiangshan , dri-devel , Ben Segall , Linux-MM , "open list:KERNEL SELFTEST FRAMEWORK" , Will Deacon , Ard Biesheuvel , Anton Ivanov , linux-arch , Vincent Guittot , Herbert Xu , Brian Cain , linux-hexagon@vger.kernel.org, Russell King , Ingo Molnar , David Airlie , Ingo Molnar , Geert Uytterhoeven , Mel Gorman , Matt Turner , Valentin Schneider , linux-xtensa@linux-xtensa.org, Shuah Khan , "Paul E. McKenney" , Jeff Dike , intel-gfx , alpha , linux-um , Josh Triplett , Steven Rostedt , rcu@vger.kernel.org, linux-m68k , Ivan Kokshaysky , Rodrigo Vivi , Thomas Gleixner , Dietmar Eggemann , Linux ARM , Richard Henderson , Chris Zankel , Max Filippov , Linus Torvalds , LKML , Richard Weinberger , Mathieu Desnoyers , Andrew Morton , Daniel Bristot de Oliveira Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" Message-ID: <20200929082324.8famVQB5auZveQpBwcIc-bLaXiTN4xv0cMhsg7igPNs@z> On Wed 16-09-20 23:43:02, Daniel Vetter wrote: > I can > then figure out whether it's better to risk not spotting issues with > call_rcu vs slapping a memalloc_noio_save/restore around all these > critical section which force-degrades any allocation to GFP_ATOMIC at did you mean memalloc_noreclaim_* here? > most, but has the risk that we run into code that assumes "GFP_KERNEL > never fails for small stuff" and has a decidedly less tested fallback > path than rcu code. Even if the above then please note that memalloc_noreclaim_* or PF_MEMALLOC should be used with an extreme care. Essentially only for internal memory reclaimers. It grants access to _all_ the available memory so any abuse can be detrimental to the overall system operation. Allocation failure in this mode means that we are out of memory and any code relying on such an allocation has to carefuly consider failure. This is not a random allocation mode. -- Michal Hocko SUSE Labs _______________________________________________ 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=-3.6 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 8919AC47423 for ; Tue, 29 Sep 2020 08:19:46 +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 0A94220C09 for ; Tue, 29 Sep 2020 08:19:45 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=suse.com header.i=@suse.com header.b="SSpMjosS" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0A94220C09 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=suse.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=intel-gfx-bounces@lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 1E9E089996; Tue, 29 Sep 2020 08:19:45 +0000 (UTC) Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) by gabe.freedesktop.org (Postfix) with ESMTPS id B569989996; Tue, 29 Sep 2020 08:19:43 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1601367582; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=KFyfyEQCS1dcCR4BhfL+zwiQ3CuzyAy4x23tr+VkzjE=; b=SSpMjosSL8o4OPVa55QL9wIlM8PHwJpdBy+0T8Zs2+GxBxG6YA9l00PJ9Y66qcHmMfGLv9 u+g+tcEvJ7RxAvAP57LRStfEelxtPsdHOGOgFzbQCNh9qQZDiKdnSarvXzcr1YnPqWmMjI wdLRjalKNBbwgyGfH1Q3bT+vgMo4axA= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 3E86BADD8; Tue, 29 Sep 2020 08:19:42 +0000 (UTC) Date: Tue, 29 Sep 2020 10:19:38 +0200 From: Michal Hocko To: Daniel Vetter Message-ID: <20200929081938.GC22035@dhcp22.suse.cz> References: <871rj4owfn.fsf@nanos.tec.linutronix.de> <87bli75t7v.fsf@nanos.tec.linutronix.de> <20200916152956.GV29330@paulmck-ThinkPad-P72> <20200916205840.GD29330@paulmck-ThinkPad-P72> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: Subject: Re: [Intel-gfx] [patch 00/13] preempt: Make preempt count unconditional X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Juri Lelli , Peter Zijlstra , Sebastian Andrzej Siewior , Lai Jiangshan , dri-devel , Ben Segall , Linux-MM , "open list:KERNEL SELFTEST FRAMEWORK" , Will Deacon , Ard Biesheuvel , Anton Ivanov , linux-arch , Herbert Xu , Brian Cain , linux-hexagon@vger.kernel.org, Russell King , Ingo Molnar , David Airlie , Ingo Molnar , Geert Uytterhoeven , Mel Gorman , Matt Turner , Valentin Schneider , linux-xtensa@linux-xtensa.org, Shuah Khan , "Paul E. McKenney" , Jeff Dike , intel-gfx , alpha , linux-um , Josh Triplett , Steven Rostedt , rcu@vger.kernel.org, linux-m68k , Ivan Kokshaysky , Thomas Gleixner , Dietmar Eggemann , Linux ARM , Richard Henderson , Chris Zankel , Max Filippov , Linus Torvalds , LKML , Richard Weinberger , Mathieu Desnoyers , Andrew Morton , Daniel Bristot de Oliveira Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" On Wed 16-09-20 23:43:02, Daniel Vetter wrote: > I can > then figure out whether it's better to risk not spotting issues with > call_rcu vs slapping a memalloc_noio_save/restore around all these > critical section which force-degrades any allocation to GFP_ATOMIC at did you mean memalloc_noreclaim_* here? > most, but has the risk that we run into code that assumes "GFP_KERNEL > never fails for small stuff" and has a decidedly less tested fallback > path than rcu code. Even if the above then please note that memalloc_noreclaim_* or PF_MEMALLOC should be used with an extreme care. Essentially only for internal memory reclaimers. It grants access to _all_ the available memory so any abuse can be detrimental to the overall system operation. Allocation failure in this mode means that we are out of memory and any code relying on such an allocation has to carefuly consider failure. This is not a random allocation mode. -- Michal Hocko SUSE Labs _______________________________________________ Intel-gfx mailing list Intel-gfx@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/intel-gfx 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=-3.6 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 350C5C47423 for ; Tue, 29 Sep 2020 08:19:52 +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 C920B206C1 for ; Tue, 29 Sep 2020 08:19:51 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=suse.com header.i=@suse.com header.b="WFaQTV+k" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C920B206C1 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=suse.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=intel-gfx-bounces@lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 49D4489B05; Tue, 29 Sep 2020 08:19:51 +0000 (UTC) Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) by gabe.freedesktop.org (Postfix) with ESMTPS id 4F06B89B05; Tue, 29 Sep 2020 08:19:50 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1601367589; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=KFyfyEQCS1dcCR4BhfL+zwiQ3CuzyAy4x23tr+VkzjE=; b=WFaQTV+kmp2Dcf4ETP9+6ZNrPfy9q5pMDECagrCQ3MjluCnYeqMkFTw/YcJHGz2iksDQw9 srvpAmlMUEz2D9SjbkwSKNyTXnnl0c+U97e7qNgFVE9O8k3lMFBfs0YlvFJAzRLJyf+n+C wZ5d1Zkp/fxHdHhoVK5syk5dxSgYigs= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id C7EE3B29F; Tue, 29 Sep 2020 08:19:48 +0000 (UTC) Date: Tue, 29 Sep 2020 10:19:48 +0200 From: Michal Hocko To: Daniel Vetter Message-ID: <20200929081938.GC22035@dhcp22.suse.cz> References: <871rj4owfn.fsf@nanos.tec.linutronix.de> <87bli75t7v.fsf@nanos.tec.linutronix.de> <20200916152956.GV29330@paulmck-ThinkPad-P72> <20200916205840.GD29330@paulmck-ThinkPad-P72> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: Subject: Re: [Intel-gfx] [patch 00/13] preempt: Make preempt count unconditional X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Juri Lelli , Peter Zijlstra , Sebastian Andrzej Siewior , Lai Jiangshan , dri-devel , Ben Segall , Linux-MM , "open list:KERNEL SELFTEST FRAMEWORK" , Will Deacon , Ard Biesheuvel , Anton Ivanov , linux-arch , Herbert Xu , Brian Cain , linux-hexagon@vger.kernel.org, Russell King , Ingo Molnar , David Airlie , Ingo Molnar , Geert Uytterhoeven , Mel Gorman , Matt Turner , Valentin Schneider , linux-xtensa@linux-xtensa.org, Shuah Khan , "Paul E. McKenney" , Jeff Dike , intel-gfx , alpha , linux-um , Josh Triplett , Steven Rostedt , rcu@vger.kernel.org, linux-m68k , Ivan Kokshaysky , Thomas Gleixner , Dietmar Eggemann , Linux ARM , Richard Henderson , Chris Zankel , Max Filippov , Linus Torvalds , LKML , Richard Weinberger , Mathieu Desnoyers , Andrew Morton , Daniel Bristot de Oliveira Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" Message-ID: <20200929081948.Adqz3HYptqIrvGp8gPwfSc40ueLQlI7RVmAJXBpnuew@z> On Wed 16-09-20 23:43:02, Daniel Vetter wrote: > I can > then figure out whether it's better to risk not spotting issues with > call_rcu vs slapping a memalloc_noio_save/restore around all these > critical section which force-degrades any allocation to GFP_ATOMIC at did you mean memalloc_noreclaim_* here? > most, but has the risk that we run into code that assumes "GFP_KERNEL > never fails for small stuff" and has a decidedly less tested fallback > path than rcu code. Even if the above then please note that memalloc_noreclaim_* or PF_MEMALLOC should be used with an extreme care. Essentially only for internal memory reclaimers. It grants access to _all_ the available memory so any abuse can be detrimental to the overall system operation. Allocation failure in this mode means that we are out of memory and any code relying on such an allocation has to carefuly consider failure. This is not a random allocation mode. -- Michal Hocko SUSE Labs _______________________________________________ Intel-gfx mailing list Intel-gfx@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/intel-gfx 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=-3.6 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 775A5C47420 for ; Tue, 29 Sep 2020 08:20:13 +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 2143121974 for ; Tue, 29 Sep 2020 08:20:12 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=suse.com header.i=@suse.com header.b="pr56FUr2" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2143121974 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=suse.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=intel-gfx-bounces@lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 6FD2789AF3; Tue, 29 Sep 2020 08:20:12 +0000 (UTC) Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) by gabe.freedesktop.org (Postfix) with ESMTPS id 346AF89AF3; Tue, 29 Sep 2020 08:20:11 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1601367609; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=KFyfyEQCS1dcCR4BhfL+zwiQ3CuzyAy4x23tr+VkzjE=; b=pr56FUr28WzVjlye8ocfuUATkeSwhUXvbjPgGkEbab2FCVC+0BKyl8PhOHOFpR/zRWD2YJ XkENxEAzZ+xaNySUfCCAfperdR1yK017PGgjlx8BHtiTSBrVceVD6B+fvb12QX9yuBiWP6 UV9FaMEAQthXh0P6zC/B1D/pMFgxjZ8= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 981CFB2AE; Tue, 29 Sep 2020 08:20:09 +0000 (UTC) Date: Tue, 29 Sep 2020 10:20:08 +0200 From: Michal Hocko To: Daniel Vetter Message-ID: <20200929081938.GC22035@dhcp22.suse.cz> References: <871rj4owfn.fsf@nanos.tec.linutronix.de> <87bli75t7v.fsf@nanos.tec.linutronix.de> <20200916152956.GV29330@paulmck-ThinkPad-P72> <20200916205840.GD29330@paulmck-ThinkPad-P72> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: Subject: Re: [Intel-gfx] [patch 00/13] preempt: Make preempt count unconditional X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Juri Lelli , Peter Zijlstra , Sebastian Andrzej Siewior , Lai Jiangshan , dri-devel , Ben Segall , Linux-MM , "open list:KERNEL SELFTEST FRAMEWORK" , Will Deacon , Ard Biesheuvel , Anton Ivanov , linux-arch , Herbert Xu , Brian Cain , linux-hexagon@vger.kernel.org, Russell King , Ingo Molnar , David Airlie , Ingo Molnar , Geert Uytterhoeven , Mel Gorman , Matt Turner , Valentin Schneider , linux-xtensa@linux-xtensa.org, Shuah Khan , "Paul E. McKenney" , Jeff Dike , intel-gfx , alpha , linux-um , Josh Triplett , Steven Rostedt , rcu@vger.kernel.org, linux-m68k , Ivan Kokshaysky , Thomas Gleixner , Dietmar Eggemann , Linux ARM , Richard Henderson , Chris Zankel , Max Filippov , Linus Torvalds , LKML , Richard Weinberger , Mathieu Desnoyers , Andrew Morton , Daniel Bristot de Oliveira Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" Message-ID: <20200929082008.S7hCrmQRfpYkcAjIo2TAnYchy0xO9lJn7IPIopNtL8Y@z> On Wed 16-09-20 23:43:02, Daniel Vetter wrote: > I can > then figure out whether it's better to risk not spotting issues with > call_rcu vs slapping a memalloc_noio_save/restore around all these > critical section which force-degrades any allocation to GFP_ATOMIC at did you mean memalloc_noreclaim_* here? > most, but has the risk that we run into code that assumes "GFP_KERNEL > never fails for small stuff" and has a decidedly less tested fallback > path than rcu code. Even if the above then please note that memalloc_noreclaim_* or PF_MEMALLOC should be used with an extreme care. Essentially only for internal memory reclaimers. It grants access to _all_ the available memory so any abuse can be detrimental to the overall system operation. Allocation failure in this mode means that we are out of memory and any code relying on such an allocation has to carefuly consider failure. This is not a random allocation mode. -- Michal Hocko SUSE Labs _______________________________________________ Intel-gfx mailing list Intel-gfx@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/intel-gfx 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=-5.1 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 E8DE8C4346E for ; Tue, 29 Sep 2020 08:21:26 +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 68DE920773 for ; Tue, 29 Sep 2020 08:21:26 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=suse.com header.i=@suse.com header.b="kYjuvZ+i" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 68DE920773 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=suse.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=intel-gfx-bounces@lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id DE47C89C80; Tue, 29 Sep 2020 08:21:25 +0000 (UTC) Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) by gabe.freedesktop.org (Postfix) with ESMTPS id B218689C2C; Tue, 29 Sep 2020 08:21:23 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1601367682; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=KFyfyEQCS1dcCR4BhfL+zwiQ3CuzyAy4x23tr+VkzjE=; b=kYjuvZ+ilRICWeNF3tv+sX4B6qR0l26SNFX+2yuqmAbG6VZsVdy+/ab4DWFA/2mAPMzvho sWiMi4hR4DtnoNBd3zA9aScladT2LR3g7zk3zp4xXinjBQFShKRtNv5abZ+aKM+mJdoLfs LfJPGyvdVLHOxuKwI+4KWXzshc3e4XY= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 4162CACA3; Tue, 29 Sep 2020 08:21:22 +0000 (UTC) Date: Tue, 29 Sep 2020 10:21:21 +0200 From: Michal Hocko To: Daniel Vetter Message-ID: <20200929081938.GC22035@dhcp22.suse.cz> References: <871rj4owfn.fsf@nanos.tec.linutronix.de> <87bli75t7v.fsf@nanos.tec.linutronix.de> <20200916152956.GV29330@paulmck-ThinkPad-P72> <20200916205840.GD29330@paulmck-ThinkPad-P72> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Subject: Re: [Intel-gfx] [patch 00/13] preempt: Make preempt count unconditional X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Juri Lelli , Peter Zijlstra , Sebastian Andrzej Siewior , Lai Jiangshan , dri-devel , Ben Segall , Linux-MM , "open list:KERNEL SELFTEST FRAMEWORK" , Will Deacon , Ard Biesheuvel , Anton Ivanov , linux-arch , Herbert Xu , Brian Cain , linux-hexagon@vger.kernel.org, Russell King , Ingo Molnar , David Airlie , Ingo Molnar , Geert Uytterhoeven , Mel Gorman , Matt Turner , Valentin Schneider , linux-xtensa@linux-xtensa.org, Shuah Khan , "Paul E. McKenney" , Jeff Dike , intel-gfx , alpha , linux-um , Josh Triplett , Steven Rostedt , rcu@vger.kernel.org, linux-m68k , Ivan Kokshaysky , Thomas Gleixner , Dietmar Eggemann , Linux ARM , Richard Henderson , Chris Zankel , Max Filippov , Linus Torvalds , LKML , Richard Weinberger , Mathieu Desnoyers , Andrew Morton , Daniel Bristot de Oliveira Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" Message-ID: <20200929082121.5YVpvTrVCGBZs1h7zSLWWk4FeqUP2AEkncT-kl3LwVo@z> On Wed 16-09-20 23:43:02, Daniel Vetter wrote: > I can > then figure out whether it's better to risk not spotting issues with > call_rcu vs slapping a memalloc_noio_save/restore around all these > critical section which force-degrades any allocation to GFP_ATOMIC at did you mean memalloc_noreclaim_* here? > most, but has the risk that we run into code that assumes "GFP_KERNEL > never fails for small stuff" and has a decidedly less tested fallback > path than rcu code. Even if the above then please note that memalloc_noreclaim_* or PF_MEMALLOC should be used with an extreme care. Essentially only for internal memory reclaimers. It grants access to _all_ the available memory so any abuse can be detrimental to the overall system operation. Allocation failure in this mode means that we are out of memory and any code relying on such an allocation has to carefuly consider failure. This is not a random allocation mode. -- Michal Hocko SUSE Labs _______________________________________________ Intel-gfx mailing list Intel-gfx@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/intel-gfx 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=-5.1 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 54BD3C47423 for ; Tue, 29 Sep 2020 08:23:29 +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 083C820C09 for ; Tue, 29 Sep 2020 08:23:28 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=suse.com header.i=@suse.com header.b="Yx+4OiWz" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 083C820C09 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=suse.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=intel-gfx-bounces@lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 8312489C3B; Tue, 29 Sep 2020 08:23:28 +0000 (UTC) Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) by gabe.freedesktop.org (Postfix) with ESMTPS id 83D7189C3B; Tue, 29 Sep 2020 08:23:26 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1601367805; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=KFyfyEQCS1dcCR4BhfL+zwiQ3CuzyAy4x23tr+VkzjE=; b=Yx+4OiWzh8hL3oRWBVwsl7OoNxopUmSyQasLhmn1G1pwm5WeUKovPN8LH2bdOC7Tf1qJAG BQKht+ljEQ7JSXztBWuZ/SDej3VcAwduMW5YketNY8WVwtpxMMor30Pmo+P2rpxR7SkCAG TBCtVCqjpOLjck1NyY3qWCFDobpueAs= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 0860EB2A1; Tue, 29 Sep 2020 08:23:25 +0000 (UTC) Date: Tue, 29 Sep 2020 10:23:24 +0200 From: Michal Hocko To: Daniel Vetter Message-ID: <20200929081938.GC22035@dhcp22.suse.cz> References: <871rj4owfn.fsf@nanos.tec.linutronix.de> <87bli75t7v.fsf@nanos.tec.linutronix.de> <20200916152956.GV29330@paulmck-ThinkPad-P72> <20200916205840.GD29330@paulmck-ThinkPad-P72> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Subject: Re: [Intel-gfx] [patch 00/13] preempt: Make preempt count unconditional X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Juri Lelli , Peter Zijlstra , Sebastian Andrzej Siewior , Lai Jiangshan , dri-devel , Ben Segall , Linux-MM , "open list:KERNEL SELFTEST FRAMEWORK" , Will Deacon , Ard Biesheuvel , Anton Ivanov , linux-arch , Herbert Xu , Brian Cain , linux-hexagon@vger.kernel.org, Russell King , Ingo Molnar , David Airlie , Ingo Molnar , Geert Uytterhoeven , Mel Gorman , Matt Turner , Valentin Schneider , linux-xtensa@linux-xtensa.org, Shuah Khan , "Paul E. McKenney" , Jeff Dike , intel-gfx , alpha , linux-um , Josh Triplett , Steven Rostedt , rcu@vger.kernel.org, linux-m68k , Ivan Kokshaysky , Thomas Gleixner , Dietmar Eggemann , Linux ARM , Richard Henderson , Chris Zankel , Max Filippov , Linus Torvalds , LKML , Richard Weinberger , Mathieu Desnoyers , Andrew Morton , Daniel Bristot de Oliveira Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" Message-ID: <20200929082324.HftM9Jl9iqt0ZmCTD_jW4UAADw6JfJX1PNMdnJXRS_Q@z> On Wed 16-09-20 23:43:02, Daniel Vetter wrote: > I can > then figure out whether it's better to risk not spotting issues with > call_rcu vs slapping a memalloc_noio_save/restore around all these > critical section which force-degrades any allocation to GFP_ATOMIC at did you mean memalloc_noreclaim_* here? > most, but has the risk that we run into code that assumes "GFP_KERNEL > never fails for small stuff" and has a decidedly less tested fallback > path than rcu code. Even if the above then please note that memalloc_noreclaim_* or PF_MEMALLOC should be used with an extreme care. Essentially only for internal memory reclaimers. It grants access to _all_ the available memory so any abuse can be detrimental to the overall system operation. Allocation failure in this mode means that we are out of memory and any code relying on such an allocation has to carefuly consider failure. This is not a random allocation mode. -- Michal Hocko SUSE Labs _______________________________________________ Intel-gfx mailing list Intel-gfx@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/intel-gfx From mboxrd@z Thu Jan 1 00:00:00 1970 From: Michal Hocko Subject: Re: [patch 00/13] preempt: Make preempt count unconditional Date: Tue, 29 Sep 2020 10:19:38 +0200 Message-ID: <20200929081938.GC22035@dhcp22.suse.cz> References: <871rj4owfn.fsf@nanos.tec.linutronix.de> <87bli75t7v.fsf@nanos.tec.linutronix.de> <20200916152956.GV29330@paulmck-ThinkPad-P72> <20200916205840.GD29330@paulmck-ThinkPad-P72> Mime-Version: 1.0 Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1601367582; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=KFyfyEQCS1dcCR4BhfL+zwiQ3CuzyAy4x23tr+VkzjE=; b=SSpMjosSL8o4OPVa55QL9wIlM8PHwJpdBy+0T8Zs2+GxBxG6YA9l00PJ9Y66qcHmMfGLv9 u+g+tcEvJ7RxAvAP57LRStfEelxtPsdHOGOgFzbQCNh9qQZDiKdnSarvXzcr1YnPqWmMjI wdLRjalKNBbwgyGfH1Q3bT+vgMo4axA= Content-Disposition: inline In-Reply-To: List-ID: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Daniel Vetter Cc: "Paul E. McKenney" , Juri Lelli , Peter Zijlstra , Sebastian Andrzej Siewior , Lai Jiangshan , dri-devel , Ben Segall , Linux-MM , "open list:KERNEL SELFTEST FRAMEWORK" , linux-hexagon@vger.kernel.org, Will Deacon , Ingo Molnar , Anton Ivanov , linux-arch , Vincent Guittot , Herbert Xu , Brian Cain , Richard Weinberger , Russell King On Wed 16-09-20 23:43:02, Daniel Vetter wrote: > I can > then figure out whether it's better to risk not spotting issues with > call_rcu vs slapping a memalloc_noio_save/restore around all these > critical section which force-degrades any allocation to GFP_ATOMIC at did you mean memalloc_noreclaim_* here? > most, but has the risk that we run into code that assumes "GFP_KERNEL > never fails for small stuff" and has a decidedly less tested fallback > path than rcu code. Even if the above then please note that memalloc_noreclaim_* or PF_MEMALLOC should be used with an extreme care. Essentially only for internal memory reclaimers. It grants access to _all_ the available memory so any abuse can be detrimental to the overall system operation. Allocation failure in this mode means that we are out of memory and any code relying on such an allocation has to carefuly consider failure. This is not a random allocation mode. -- Michal Hocko SUSE Labs