linux-kernel - [RFC PATCH 0/5] replace runtime slub_debug toggling with more capable boot parameter

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Message-Id: <20200602141519.7099-1-vbabka@suse.cz>
Date:   Tue,  2 Jun 2020 16:15:14 +0200
From:   Vlastimil Babka <vbabka@...e.cz>
To:     Christoph Lameter <cl@...ux.com>,
        Pekka Enberg <penberg@...nel.org>,
        David Rientjes <rientjes@...gle.com>,
        Joonsoo Kim <iamjoonsoo.kim@....com>
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        kernel-team@...roid.com, vinmenon@...eaurora.org,
        Kees Cook <keescook@...omium.org>,
        Matthew Garrett <mjg59@...gle.com>,
        Vlastimil Babka <vbabka@...e.cz>, Jann Horn <jannh@...gle.com>,
        Vijayanand Jitta <vjitta@...eaurora.org>
Subject: [RFC PATCH 0/5] replace runtime slub_debug toggling with more capable boot parameter

Hi,

we had recently reports [1,2] of troubles with runtime writes to various SLUB
per-cache sysfs files related to slub_debug or tuning leading to crashes. I have
inspected all those writable files and the rather unfortunate result is that
most of them are made read-only by this patchset, as fixing the issues doesn't
seem viable. Details for each are given in each patch. I expect some
resistance, hence the RFC.

The runtime toggles were however necessary for the use case described in [3],
so the first patch extends the slub_debug boot parameter syntax to achieve the
same configuration without runtime toggles. That should hopefully make the
changes more feasible.

[1] https://lkml.kernel.org/r/1580379523-32272-1-git-send-email-vjitta@codeaurora.org
[2] https://lore.kernel.org/r/CAG48ez31PP--h6_FzVyfJ4H86QYczAFPdxtJHUEEan+7VJETAQ@mail.gmail.com
[3] https://lore.kernel.org/r/1383cd32-1ddc-4dac-b5f8-9c42282fa81c@codeaurora.org

Vlastimil Babka (5):
  mm, slub: extend slub_debug syntax for multiple blocks
  mm, slub: make some slub_debug related attributes read-only
  mm, slub: remove runtime allocation order changes
  mm, slub: make remaining slub_debug related attributes read-only
  mm, slub: make reclaim_account attribute read-only

 .../admin-guide/kernel-parameters.txt         |   2 +-
 Documentation/vm/slub.rst                     |  36 +-
 mm/slub.c                                     | 315 ++++++++----------
 3 files changed, 163 insertions(+), 190 deletions(-)

-- 
2.26.2