From: Andrew Morton <akpm@linux-foundation.org>
To: Yu Zhao <yuzhao@google.com>
Cc: "Justin Forbes" <jforbes@fedoraproject.org>,
"Stephen Rothwell" <sfr@rothwell.id.au>,
Linux-MM <linux-mm@kvack.org>, "Andi Kleen" <ak@linux.intel.com>,
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"Barry Song" <21cnbao@gmail.com>,
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"Linus Torvalds" <torvalds@linux-foundation.org>,
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"Jan Alexander Steffens" <heftig@archlinux.org>,
"Oleksandr Natalenko" <oleksandr@natalenko.name>,
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"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 14:32:20 -0700 [thread overview]
Message-ID: <20220415143220.cc37b0b0a368ed2bf2a821f8@linux-foundation.org> (raw)
In-Reply-To: <CAOUHufYsjwMGMFCfYoh79rFZqwqS1jDihcBS9sHd-gBxEAD3Ug@mail.gmail.com>
On Fri, 15 Apr 2022 14:11:32 -0600 Yu Zhao <yuzhao@google.com> wrote:
> >
> > I grabbed
> > https://kojipkgs.fedoraproject.org//packages/kernel/5.18.0/0.rc2.23.fc37/src/kernel-5.18.0-0.rc2.23.fc37.src.rpm
> > and
>
> Yes, Fedora/RHEL is one concrete example of the model I mentioned
> above (experimental/stable). I added Justin, the Fedora kernel
> maintainer, and he can further clarify.
>
> If we don't want more VM_BUG_ONs, I'll remove them. But (let me
> reiterate) it seems to me that just defeats the purpose of having
> CONFIG_DEBUG_VM.
>
Well, I feel your pain. It was never expected that VM_BUG_ON() would
get subverted in this fashion.
We could create a new MM-developer-only assertion. Might even call it
MM_BUG_ON(). With compile-time enablement but perhaps not a runtime
switch.
With nice simple semantics, please. Like "it returns void" and "if you
pass an expression with side-effects then you lose". And "if you send
a patch which produces warnings when CONFIG_MM_BUG_ON=n then you get to
switch to windows95 for a month".
Let's leave the mglru assertions in place for now and let's think about
creating something more suitable, with a view to switching mglru over
to that at a later time.
But really, none of this addresses the core problem: *_BUG_ON() often
kills the kernel. So guess what we just did? We killed the user's
kernel at the exact time when we least wished to do so: when they have
a bug to report to us. So the thing is self-defeating.
It's much much better to WARN and to attempt to continue. This makes
it much more likely that we'll get to hear about the kernel flaw.
next prev parent reply other threads:[~2022-04-15 21:32 UTC|newest]
Thread overview: 98+ 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 ` [PATCH v10 01/14] mm: x86, arm64: add arch_has_hw_pte_young() 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 ` [PATCH v10 03/14] mm/vmscan.c: refactor shrink_node() Yu Zhao
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
2022-04-16 6:50 ` Miaohe Lin
2022-04-07 3:15 ` [PATCH v10 05/14] mm: multi-gen LRU: groundwork Yu Zhao
2022-04-12 2:16 ` Andrew Morton
2022-04-12 7:06 ` Peter Zijlstra
2022-04-20 0:39 ` Yu Zhao
2022-04-20 20:07 ` Linus Torvalds
2022-04-26 22:39 ` Yu Zhao
2022-04-26 23:42 ` Andrew Morton
2022-04-27 1:18 ` Yu Zhao
2022-04-27 1:34 ` Andrew Morton
2022-04-07 3:15 ` [PATCH v10 06/14] mm: multi-gen LRU: minimal implementation Yu Zhao
2022-04-14 6:03 ` Barry Song
2022-04-14 20:36 ` Yu Zhao
2022-04-14 21:39 ` Andrew Morton
2022-04-14 22:14 ` Yu Zhao
2022-04-15 10:15 ` Barry Song
2022-04-15 20:17 ` Yu Zhao
2022-04-15 10:26 ` Barry Song
2022-04-15 20:18 ` Yu Zhao
[not found] ` <71af92d2-0777-c318-67fb-8f7d52c800bb@huawei.com>
2022-04-14 20:53 ` Yu Zhao
2022-04-15 2:23 ` Chen Wandun
2022-04-15 5:25 ` Yu Zhao
2022-04-15 6:31 ` Chen Wandun
2022-04-15 6:44 ` Yu Zhao
2022-04-15 9:27 ` Chen Wandun
2022-04-18 9:58 ` Barry Song
2022-04-19 0:53 ` Yu Zhao
2022-04-19 4:25 ` Barry Song
2022-04-19 4:36 ` Barry Song
2022-04-19 22:25 ` 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
2022-04-27 4:32 ` Aneesh Kumar K.V
2022-04-27 4:38 ` Yu Zhao
2022-04-27 5:31 ` Aneesh Kumar K V
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
2022-04-12 2:16 ` Andrew Morton
2022-04-12 7:10 ` Peter Zijlstra
2022-04-15 5:30 ` Yu Zhao
2022-04-15 1:14 ` Yu Zhao
2022-04-15 1:56 ` Andrew Morton
2022-04-15 6:25 ` Yu Zhao
2022-04-15 19:15 ` Andrew Morton
2022-04-15 20:11 ` Yu Zhao
2022-04-15 21:32 ` Andrew Morton [this message]
2022-04-15 21:36 ` Linus Torvalds
2022-04-15 22:57 ` Yu Zhao
2022-04-15 23:03 ` Linus Torvalds
2022-04-15 23:24 ` [page-reclaim] " Jesse Barnes
2022-04-15 23:31 ` Matthew Wilcox
2022-04-15 23:37 ` Jesse Barnes
2022-04-15 23:49 ` Yu Zhao
2022-04-16 16:32 ` Justin Forbes
2022-04-19 22:32 ` Yu Zhao
2022-04-29 14:10 ` zhong jiang
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 ` [PATCH v10 10/14] mm: multi-gen LRU: kill switch Yu Zhao
2022-04-12 2:16 ` Andrew Morton
2022-04-26 20:57 ` Yu Zhao
2022-04-26 22:22 ` Andrew Morton
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 ` [PATCH v10 12/14] mm: multi-gen LRU: debugfs interface Yu Zhao
2022-04-12 2:16 ` Andrew Morton
2022-04-16 0:03 ` Yu Zhao
2022-04-16 4:20 ` Andrew Morton
2022-04-26 6:59 ` Yu Zhao
2022-04-26 21:30 ` Andrew Morton
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 12:41 ` Bagas Sanjaya
2022-04-07 12:51 ` Jonathan Corbet
2022-04-12 2:16 ` Andrew Morton
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 11:39 ` Huang Shijie
2022-04-07 12:41 ` Bagas Sanjaya
2022-04-07 12:52 ` Jonathan Corbet
2022-04-08 4:48 ` Bagas Sanjaya
2022-04-12 2:16 ` Andrew Morton
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 8:31 ` Stephen Rothwell
2022-04-07 9:08 ` Yu Zhao
2022-04-07 9:41 ` Yu Zhao
2022-04-07 12:13 ` Stephen Rothwell
2022-04-08 2:08 ` Yu Zhao
2022-04-12 2:15 ` Andrew Morton
2022-04-14 5:06 ` Andrew Morton
2022-04-20 0:50 ` Yu Zhao
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