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Mon, 13 Mar 2023 16:26:19 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id xEq+KatOD2QIDwAAMHmgww (envelope-from ); Mon, 13 Mar 2023 16:26:19 +0000 Message-ID: Date: Mon, 13 Mar 2023 17:26:19 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.8.0 Subject: Re: [PATCH] mm/slub: fix help comment of SLUB_DEBUG[_ON] Content-Language: en-US To: Hyeonggon Yoo <42.hyeyoo@gmail.com>, Vernon Yang Cc: akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20230222232058.66971-1-vernon2gm@gmail.com> From: Vlastimil Babka In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 441EB100005 X-Rspamd-Server: rspam09 X-Rspam-User: X-Stat-Signature: troq1h3dfskknb1173g99fr4a9umghyg X-HE-Tag: 1678724781-88837 X-HE-Meta: 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 LgcGQFwP pacZPkw83Kv315aPOPIi33Kyxt5/7RrZE6BpZsmc9enIy1nIVsaAUuMnubHyNzmQvizafvN3or37tIuu4acdwxGkPzWjexjNMcOXGbWVdQarY8SIAVnr9TnpypTOak6+Ob0ix/w7RJFid7IRnC5apLInurgkZo6bjVUedK364N6Vs/MFraXYvqK8VE1zzJQ6PTM8tWr5AkEnZvXR/hFJkjukS3v4kj3P+VsyqH4fxkyV1E21CjPJ3K4UVMoXtRx3kCwB7UtT6fPeo6oK8KO1PN3OkTjld3fGmZwXIxfRJKp0B47khO6I+q0mQ6+gKRa0PijXbqRGI7NU2nkQCawN34YZPb6s/Z0BNJLf6 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 2/23/23 02:03, Hyeonggon Yoo wrote: > On Thu, Feb 23, 2023 at 07:20:58AM +0800, Vernon Yang wrote: >> Since commit 081248de0a02 ("kset: move /sys/slab to /sys/kernel/slab"), >> the SYSFS path of slab was modified, so fix up the help comment of >> SLUB_DEBUG to use the correct one. >> >> And now the "slub_debug" parameter on boot that is support for more >> fine grained debug control, so fix up help comment of SLUB_DEBUG_ON >> for "no support" to "support". >> >> Signed-off-by: Vernon Yang >> --- >> mm/Kconfig.debug | 12 ++++++------ >> 1 file changed, 6 insertions(+), 6 deletions(-) >> >> diff --git a/mm/Kconfig.debug b/mm/Kconfig.debug >> index fca699ad1fb0..732043bf56c6 100644 >> --- a/mm/Kconfig.debug >> +++ b/mm/Kconfig.debug >> @@ -61,8 +61,8 @@ config SLUB_DEBUG >> help >> SLUB has extensive debug support features. Disabling these can >> result in significant savings in code size. This also disables >> - SLUB sysfs support. /sys/slab will not exist and there will be >> - no support for cache validation etc. >> + SLUB sysfs support. /sys/kernel/slab will not exist and there >> + will be no support for cache validation etc. > > After commit ab4d5ed5eeda ("slub: Enable sysfs support for !CONFIG_SLUB_DEBUG"), > "Disabling SLUB_DEBUG also disables SLUB sysfs support" is not true anymore. Yeah we could say that /sys/kernel/slab will exist but will not provide e.g. cache validation. >> config SLUB_DEBUG_ON >> bool "SLUB debugging on by default" >> @@ -73,10 +73,10 @@ config SLUB_DEBUG_ON >> Boot with debugging on by default. SLUB boots by default with >> the runtime debug capabilities switched off. Enabling this is >> equivalent to specifying the "slub_debug" parameter on boot. >> - There is no support for more fine grained debug control like >> - possible with slub_debug=xxx. SLUB debugging may be switched >> - off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying >> - "slub_debug=-". >> + There is support for more fine grained debug control like >> + possible with slub_debug=xxx, details in Documentation/mm/slub.rst. >> + SLUB debugging may be switched off in a kernel built with >> + CONFIG_SLUB_DEBUG_ON by specifying "slub_debug=-". > > I think this is a misunderstanding. SLUB_DEBUG_ON is equivalent to > passing boot parameter slub_debug=FUPZ, and what the help text says is that > > "You can enable slub debugging by default using this config option but > there is no support for fine-grained control like what slub_debug > boot parameter provides." > > IOW SLUB_DEBUG_ON cannot be used to have same effect as passing > something like slub_debug=F. Agree with both comments. Vernon, will you send an updated patch? >> >> config PAGE_OWNER >> bool "Track page owner" >> -- >> 2.34.1 >> >>