From: Yu Zhao <yuzhao@google.com> To: Linus Torvalds <torvalds@linux-foundation.org> Cc: "Andrew Morton" <akpm@linux-foundation.org>, "Justin Forbes" <jforbes@fedoraproject.org>, "Stephen Rothwell" <sfr@rothwell.id.au>, Linux-MM <linux-mm@kvack.org>, "Andi Kleen" <ak@linux.intel.com>, "Aneesh Kumar" <aneesh.kumar@linux.ibm.com>, "Barry Song" <21cnbao@gmail.com>, "Catalin Marinas" <catalin.marinas@arm.com>, "Dave Hansen" <dave.hansen@linux.intel.com>, "Hillf Danton" <hdanton@sina.com>, "Jens Axboe" <axboe@kernel.dk>, "Jesse Barnes" <jsbarnes@google.com>, "Johannes Weiner" <hannes@cmpxchg.org>, "Jonathan Corbet" <corbet@lwn.net>, "Matthew Wilcox" <willy@infradead.org>, "Mel Gorman" <mgorman@suse.de>, "Michael Larabel" <Michael@michaellarabel.com>, "Michal Hocko" <mhocko@kernel.org>, "Mike Rapoport" <rppt@kernel.org>, "Rik van Riel" <riel@surriel.com>, "Vlastimil Babka" <vbabka@suse.cz>, "Will Deacon" <will@kernel.org>, "Ying Huang" <ying.huang@intel.com>, "Linux ARM" <linux-arm-kernel@lists.infradead.org>, "open list:DOCUMENTATION" <linux-doc@vger.kernel.org>, linux-kernel <linux-kernel@vger.kernel.org>, "Kernel Page Reclaim v2" <page-reclaim@google.com>, "the arch/x86 maintainers" <x86@kernel.org>, "Brian Geffon" <bgeffon@google.com>, "Jan Alexander Steffens" <heftig@archlinux.org>, "Oleksandr Natalenko" <oleksandr@natalenko.name>, "Steven Barrett" <steven@liquorix.net>, "Suleiman Souhlal" <suleiman@google.com>, "Daniel Byrne" <djbyrne@mtu.edu>, "Donald Carr" <d@chaos-reins.com>, "Holger Hoffstätte" <holger@applied-asynchrony.com>, "Konstantin Kharlamov" <Hi-Angel@yandex.ru>, "Shuang Zhai" <szhai2@cs.rochester.edu>, "Sofia Trinh" <sofia.trinh@edi.works>, "Vaibhav Jain" <vaibhav@linux.ibm.com> Subject: Re: [PATCH v10 08/14] mm: multi-gen LRU: support page table walks Date: Fri, 15 Apr 2022 17:49:09 -0600 [thread overview] Message-ID: <CAOUHufbc9oZ03CcOmQ=4KWzh_cof26Avag+WVkfOGR3+W8-OaA@mail.gmail.com> (raw) In-Reply-To: <CAHk-=whneDk3Jde3J+O-fD32VjaK+fDf9+P6jgDtr2qyo0iu2w@mail.gmail.com> On Fri, Apr 15, 2022 at 5:03 PM Linus Torvalds <torvalds@linux-foundation.org> wrote: > > On Fri, Apr 15, 2022 at 3:58 PM Yu Zhao <yuzhao@google.com> wrote: > > > > BUG_ONs are harmful but problems that trigger them would be > > presummingly less penetrating to the user base; on the other hand, > > from my experience working with some testers (ordinary users), they > > ignore WARN_ON_ONCEs until the kernel crashes. > > I don't understand your argument. > > First you say that VM_BUG_ON() is only for VM developers. I did? Probably I implied CONFIG_DEBUG_VM=y is meant for MM developers. > Then you say "some testers (ordinary users) ignore WARN_ON_ONCEs until > the kernel crashes". > > So which is it? > > VM developers, or ordinary users? Ordinary users. > Honestly, if a VM developer is ignoring a WARN_ON_ONCE() from the VM > subsystem, I don't even know what to say. Same here. I wasn't worried about kernel developers ignoring any warnings. > And for ordinary users, a WARN_ON_ONCE() is about a million times > better, becasue: > > - the machine will hopefully continue working, so they can report the warning > > - even when they don't notice them, distros tend to have automated > reporting infrastructure > > That's why I absolutely *DETEST* those stupid BUG_ON() cases - they > will often kill the machine with nasty locks held, resulting in a > completely undebuggable thing that never gets reported. > > Yes, you can be careful and only put BUG_ON() in places where recovery > is possible. But even then, they have no actual _advantages_ over just > a WARN_ON_ONCE. I hear you, and I wasn't arguing about anything, just sharing my two cents.
WARNING: multiple messages have this Message-ID (diff)
From: Yu Zhao <yuzhao@google.com> To: Linus Torvalds <torvalds@linux-foundation.org> Cc: "Andrew Morton" <akpm@linux-foundation.org>, "Justin Forbes" <jforbes@fedoraproject.org>, "Stephen Rothwell" <sfr@rothwell.id.au>, Linux-MM <linux-mm@kvack.org>, "Andi Kleen" <ak@linux.intel.com>, "Aneesh Kumar" <aneesh.kumar@linux.ibm.com>, "Barry Song" <21cnbao@gmail.com>, "Catalin Marinas" <catalin.marinas@arm.com>, "Dave Hansen" <dave.hansen@linux.intel.com>, "Hillf Danton" <hdanton@sina.com>, "Jens Axboe" <axboe@kernel.dk>, "Jesse Barnes" <jsbarnes@google.com>, "Johannes Weiner" <hannes@cmpxchg.org>, "Jonathan Corbet" <corbet@lwn.net>, "Matthew Wilcox" <willy@infradead.org>, "Mel Gorman" <mgorman@suse.de>, "Michael Larabel" <Michael@michaellarabel.com>, "Michal Hocko" <mhocko@kernel.org>, "Mike Rapoport" <rppt@kernel.org>, "Rik van Riel" <riel@surriel.com>, "Vlastimil Babka" <vbabka@suse.cz>, "Will Deacon" <will@kernel.org>, "Ying Huang" <ying.huang@intel.com>, "Linux ARM" <linux-arm-kernel@lists.infradead.org>, "open list:DOCUMENTATION" <linux-doc@vger.kernel.org>, linux-kernel <linux-kernel@vger.kernel.org>, "Kernel Page Reclaim v2" <page-reclaim@google.com>, "the arch/x86 maintainers" <x86@kernel.org>, "Brian Geffon" <bgeffon@google.com>, "Jan Alexander Steffens" <heftig@archlinux.org>, "Oleksandr Natalenko" <oleksandr@natalenko.name>, "Steven Barrett" <steven@liquorix.net>, "Suleiman Souhlal" <suleiman@google.com>, "Daniel Byrne" <djbyrne@mtu.edu>, "Donald Carr" <d@chaos-reins.com>, "Holger Hoffstätte" <holger@applied-asynchrony.com>, "Konstantin Kharlamov" <Hi-Angel@yandex.ru>, "Shuang Zhai" <szhai2@cs.rochester.edu>, "Sofia Trinh" <sofia.trinh@edi.works>, "Vaibhav Jain" <vaibhav@linux.ibm.com> Subject: Re: [PATCH v10 08/14] mm: multi-gen LRU: support page table walks Date: Fri, 15 Apr 2022 17:49:09 -0600 [thread overview] Message-ID: <CAOUHufbc9oZ03CcOmQ=4KWzh_cof26Avag+WVkfOGR3+W8-OaA@mail.gmail.com> (raw) In-Reply-To: <CAHk-=whneDk3Jde3J+O-fD32VjaK+fDf9+P6jgDtr2qyo0iu2w@mail.gmail.com> On Fri, Apr 15, 2022 at 5:03 PM Linus Torvalds <torvalds@linux-foundation.org> wrote: > > On Fri, Apr 15, 2022 at 3:58 PM Yu Zhao <yuzhao@google.com> wrote: > > > > BUG_ONs are harmful but problems that trigger them would be > > presummingly less penetrating to the user base; on the other hand, > > from my experience working with some testers (ordinary users), they > > ignore WARN_ON_ONCEs until the kernel crashes. > > I don't understand your argument. > > First you say that VM_BUG_ON() is only for VM developers. I did? Probably I implied CONFIG_DEBUG_VM=y is meant for MM developers. > Then you say "some testers (ordinary users) ignore WARN_ON_ONCEs until > the kernel crashes". > > So which is it? > > VM developers, or ordinary users? Ordinary users. > Honestly, if a VM developer is ignoring a WARN_ON_ONCE() from the VM > subsystem, I don't even know what to say. Same here. I wasn't worried about kernel developers ignoring any warnings. > And for ordinary users, a WARN_ON_ONCE() is about a million times > better, becasue: > > - the machine will hopefully continue working, so they can report the warning > > - even when they don't notice them, distros tend to have automated > reporting infrastructure > > That's why I absolutely *DETEST* those stupid BUG_ON() cases - they > will often kill the machine with nasty locks held, resulting in a > completely undebuggable thing that never gets reported. > > Yes, you can be careful and only put BUG_ON() in places where recovery > is possible. But even then, they have no actual _advantages_ over just > a WARN_ON_ONCE. I hear you, and I wasn't arguing about anything, just sharing my two cents. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2022-04-15 23:49 UTC|newest] Thread overview: 198+ messages / expand[flat|nested] mbox.gz Atom feed top 2022-04-07 3:15 [PATCH v10 00/14] Multi-Gen LRU Framework Yu Zhao 2022-04-07 3:15 ` Yu Zhao 2022-04-07 3:15 ` [PATCH v10 01/14] mm: x86, arm64: add arch_has_hw_pte_young() Yu Zhao 2022-04-07 3:15 ` Yu Zhao 2022-04-07 3:15 ` [PATCH v10 02/14] mm: x86: add CONFIG_ARCH_HAS_NONLEAF_PMD_YOUNG Yu Zhao 2022-04-07 3:15 ` Yu Zhao 2022-04-07 3:15 ` [PATCH v10 03/14] mm/vmscan.c: refactor shrink_node() Yu Zhao 2022-04-07 3:15 ` Yu Zhao 2022-04-16 6:48 ` Miaohe Lin 2022-04-16 6:48 ` Miaohe Lin 2022-04-07 3:15 ` [PATCH v10 04/14] Revert "include/linux/mm_inline.h: fold __update_lru_size() into its sole caller" Yu Zhao 2022-04-07 3:15 ` Yu Zhao 2022-04-16 6:50 ` Miaohe Lin 2022-04-16 6:50 ` Miaohe Lin 2022-04-07 3:15 ` [PATCH v10 05/14] mm: multi-gen LRU: groundwork Yu Zhao 2022-04-07 3:15 ` Yu Zhao 2022-04-12 2:16 ` Andrew Morton 2022-04-12 2:16 ` Andrew Morton 2022-04-12 7:06 ` Peter Zijlstra 2022-04-12 7:06 ` Peter Zijlstra 2022-04-20 0:39 ` Yu Zhao 2022-04-20 0:39 ` Yu Zhao 2022-04-20 20:07 ` Linus Torvalds 2022-04-20 20:07 ` Linus Torvalds 2022-04-26 22:39 ` Yu Zhao 2022-04-26 22:39 ` Yu Zhao 2022-04-26 23:42 ` Andrew Morton 2022-04-26 23:42 ` Andrew Morton 2022-04-27 1:18 ` Yu Zhao 2022-04-27 1:18 ` Yu Zhao 2022-04-27 1:34 ` Andrew Morton 2022-04-27 1:34 ` Andrew Morton 2022-04-07 3:15 ` [PATCH v10 06/14] mm: multi-gen LRU: minimal implementation Yu Zhao 2022-04-07 3:15 ` Yu Zhao 2022-04-14 6:03 ` Barry Song 2022-04-14 6:03 ` Barry Song 2022-04-14 20:36 ` Yu Zhao 2022-04-14 20:36 ` Yu Zhao 2022-04-14 21:39 ` Andrew Morton 2022-04-14 21:39 ` Andrew Morton 2022-04-14 22:14 ` Yu Zhao 2022-04-14 22:14 ` Yu Zhao 2022-04-15 10:15 ` Barry Song 2022-04-15 10:15 ` Barry Song 2022-04-15 20:17 ` Yu Zhao 2022-04-15 20:17 ` Yu Zhao 2022-04-15 10:26 ` Barry Song 2022-04-15 10:26 ` Barry Song 2022-04-15 20:18 ` Yu Zhao 2022-04-15 20:18 ` Yu Zhao 2022-04-14 11:47 ` Chen Wandun 2022-04-14 11:47 ` Chen Wandun 2022-04-14 20:53 ` Yu Zhao 2022-04-14 20:53 ` Yu Zhao 2022-04-15 2:23 ` Chen Wandun 2022-04-15 2:23 ` Chen Wandun 2022-04-15 5:25 ` Yu Zhao 2022-04-15 5:25 ` Yu Zhao 2022-04-15 6:31 ` Chen Wandun 2022-04-15 6:31 ` Chen Wandun 2022-04-15 6:44 ` Yu Zhao 2022-04-15 6:44 ` Yu Zhao 2022-04-15 9:27 ` Chen Wandun 2022-04-15 9:27 ` Chen Wandun 2022-04-18 9:58 ` Barry Song 2022-04-18 9:58 ` Barry Song 2022-04-19 0:53 ` Yu Zhao 2022-04-19 0:53 ` Yu Zhao 2022-04-19 4:25 ` Barry Song 2022-04-19 4:25 ` Barry Song 2022-04-19 4:36 ` Barry Song 2022-04-19 4:36 ` Barry Song 2022-04-19 22:25 ` Yu Zhao 2022-04-19 22:25 ` Yu Zhao 2022-04-19 22:20 ` Yu Zhao 2022-04-19 22:20 ` Yu Zhao 2022-04-07 3:15 ` [PATCH v10 07/14] mm: multi-gen LRU: exploit locality in rmap Yu Zhao 2022-04-07 3:15 ` Yu Zhao 2022-04-27 4:32 ` Aneesh Kumar K.V 2022-04-27 4:32 ` Aneesh Kumar K.V 2022-04-27 4:38 ` Yu Zhao 2022-04-27 4:38 ` Yu Zhao 2022-04-27 5:31 ` Aneesh Kumar K V 2022-04-27 5:31 ` Aneesh Kumar K V 2022-04-27 6:00 ` Yu Zhao 2022-04-27 6:00 ` Yu Zhao 2022-04-07 3:15 ` [PATCH v10 08/14] mm: multi-gen LRU: support page table walks Yu Zhao 2022-04-07 3:15 ` Yu Zhao 2022-04-12 2:16 ` Andrew Morton 2022-04-12 2:16 ` Andrew Morton 2022-04-12 7:10 ` Peter Zijlstra 2022-04-12 7:10 ` Peter Zijlstra 2022-04-15 5:30 ` Yu Zhao 2022-04-15 5:30 ` Yu Zhao 2022-04-15 1:14 ` Yu Zhao 2022-04-15 1:14 ` Yu Zhao 2022-04-15 1:56 ` Andrew Morton 2022-04-15 1:56 ` Andrew Morton 2022-04-15 6:25 ` Yu Zhao 2022-04-15 6:25 ` Yu Zhao 2022-04-15 19:15 ` Andrew Morton 2022-04-15 19:15 ` Andrew Morton 2022-04-15 20:11 ` Yu Zhao 2022-04-15 20:11 ` Yu Zhao 2022-04-15 21:32 ` Andrew Morton 2022-04-15 21:32 ` Andrew Morton 2022-04-15 21:36 ` Linus Torvalds 2022-04-15 21:36 ` Linus Torvalds 2022-04-15 22:57 ` Yu Zhao 2022-04-15 22:57 ` Yu Zhao 2022-04-15 23:03 ` Linus Torvalds 2022-04-15 23:03 ` Linus Torvalds 2022-04-15 23:24 ` [page-reclaim] " Jesse Barnes 2022-04-15 23:24 ` Jesse Barnes 2022-04-15 23:31 ` Matthew Wilcox 2022-04-15 23:31 ` Matthew Wilcox 2022-04-15 23:37 ` Jesse Barnes 2022-04-15 23:37 ` Jesse Barnes 2022-04-15 23:49 ` Yu Zhao [this message] 2022-04-15 23:49 ` Yu Zhao 2022-04-16 16:32 ` Justin Forbes 2022-04-16 16:32 ` Justin Forbes 2022-04-19 22:32 ` Yu Zhao 2022-04-19 22:32 ` Yu Zhao 2022-04-29 14:10 ` zhong jiang 2022-04-29 14:10 ` zhong jiang 2022-04-30 8:34 ` Yu Zhao 2022-04-30 8:34 ` Yu Zhao 2022-04-07 3:15 ` [PATCH v10 09/14] mm: multi-gen LRU: optimize multiple memcgs Yu Zhao 2022-04-07 3:15 ` Yu Zhao 2022-04-07 3:15 ` [PATCH v10 10/14] mm: multi-gen LRU: kill switch Yu Zhao 2022-04-07 3:15 ` Yu Zhao 2022-04-12 2:16 ` Andrew Morton 2022-04-12 2:16 ` Andrew Morton 2022-04-26 20:57 ` Yu Zhao 2022-04-26 20:57 ` Yu Zhao 2022-04-26 22:22 ` Andrew Morton 2022-04-26 22:22 ` Andrew Morton 2022-04-27 1:11 ` Yu Zhao 2022-04-27 1:11 ` Yu Zhao 2022-04-07 3:15 ` [PATCH v10 11/14] mm: multi-gen LRU: thrashing prevention Yu Zhao 2022-04-07 3:15 ` Yu Zhao 2022-04-07 3:15 ` [PATCH v10 12/14] mm: multi-gen LRU: debugfs interface Yu Zhao 2022-04-07 3:15 ` Yu Zhao 2022-04-12 2:16 ` Andrew Morton 2022-04-12 2:16 ` Andrew Morton 2022-04-16 0:03 ` Yu Zhao 2022-04-16 0:03 ` Yu Zhao 2022-04-16 4:20 ` Andrew Morton 2022-04-16 4:20 ` Andrew Morton 2022-04-26 6:59 ` Yu Zhao 2022-04-26 6:59 ` Yu Zhao 2022-04-26 21:30 ` Andrew Morton 2022-04-26 21:30 ` Andrew Morton 2022-04-26 22:15 ` Yu Zhao 2022-04-26 22:15 ` Yu Zhao 2022-04-07 3:15 ` [PATCH v10 13/14] mm: multi-gen LRU: admin guide Yu Zhao 2022-04-07 3:15 ` Yu Zhao 2022-04-07 12:41 ` Bagas Sanjaya 2022-04-07 12:41 ` Bagas Sanjaya 2022-04-07 12:51 ` Jonathan Corbet 2022-04-07 12:51 ` Jonathan Corbet 2022-04-12 2:16 ` Andrew Morton 2022-04-12 2:16 ` Andrew Morton 2022-04-16 2:22 ` Yu Zhao 2022-04-16 2:22 ` Yu Zhao 2022-04-07 3:15 ` [PATCH v10 14/14] mm: multi-gen LRU: design doc Yu Zhao 2022-04-07 3:15 ` Yu Zhao 2022-04-07 11:39 ` Huang Shijie 2022-04-07 11:39 ` Huang Shijie 2022-04-07 12:41 ` Bagas Sanjaya 2022-04-07 12:41 ` Bagas Sanjaya 2022-04-07 12:52 ` Jonathan Corbet 2022-04-07 12:52 ` Jonathan Corbet 2022-04-08 4:48 ` Bagas Sanjaya 2022-04-08 4:48 ` Bagas Sanjaya 2022-04-12 2:16 ` Andrew Morton 2022-04-12 2:16 ` Andrew Morton 2022-04-26 7:42 ` Yu Zhao 2022-04-26 7:42 ` Yu Zhao 2022-04-07 3:24 ` [PATCH v10 00/14] Multi-Gen LRU Framework Yu Zhao 2022-04-07 3:24 ` Yu Zhao 2022-04-07 8:31 ` Stephen Rothwell 2022-04-07 8:31 ` Stephen Rothwell 2022-04-07 9:08 ` Yu Zhao 2022-04-07 9:08 ` Yu Zhao 2022-04-07 9:41 ` Yu Zhao 2022-04-07 9:41 ` Yu Zhao 2022-04-07 12:13 ` Stephen Rothwell 2022-04-07 12:13 ` Stephen Rothwell 2022-04-08 2:08 ` Yu Zhao 2022-04-08 2:08 ` Yu Zhao 2022-04-12 2:15 ` Andrew Morton 2022-04-12 2:15 ` Andrew Morton 2022-04-14 5:06 ` Andrew Morton 2022-04-14 5:06 ` Andrew Morton 2022-04-20 0:50 ` Yu Zhao 2022-04-20 0:50 ` Yu Zhao
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