linux-kernel - Re: [RFC PATCH 2/3] mm/slub: unify all sl[au]b parameters with "slab

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Message-ID: <202312021329.86D56FA@keescook>
Date:   Sat, 2 Dec 2023 13:30:07 -0800
From:   Kees Cook <keescook@...omium.org>
To:     Vlastimil Babka <vbabka@...e.cz>
Cc:     "Song, Xiongwei" <Xiongwei.Song@...driver.com>,
        "sxwjean@...com" <sxwjean@...com>,
        "42.hyeyoo@...il.com" <42.hyeyoo@...il.com>,
        "cl@...ux.com" <cl@...ux.com>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "penberg@...nel.org" <penberg@...nel.org>,
        "rientjes@...gle.com" <rientjes@...gle.com>,
        "iamjoonsoo.kim@....com" <iamjoonsoo.kim@....com>,
        "roman.gushchin@...ux.dev" <roman.gushchin@...ux.dev>,
        "corbet@....net" <corbet@....net>, "arnd@...db.de" <arnd@...db.de>,
        "akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
        "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        "linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [RFC PATCH 2/3] mm/slub: unify all sl[au]b parameters with
 "slab_$param"

On Sat, Dec 02, 2023 at 07:12:25PM +0100, Vlastimil Babka wrote:
> On 12/2/23 05:23, Song, Xiongwei wrote:
> > 
> > 
> >> -----Original Message-----
> >> From: Kees Cook <keescook@...omium.org>
> >> Sent: Saturday, December 2, 2023 1:48 AM
> >> To: sxwjean@...com
> >> Cc: vbabka@...e.cz; 42.hyeyoo@...il.com; cl@...ux.com; linux-mm@...ck.org;
> >> penberg@...nel.org; rientjes@...gle.com; iamjoonsoo.kim@....com;
> >> roman.gushchin@...ux.dev; corbet@....net; arnd@...db.de; akpm@...ux-
> >> foundation.org; gregkh@...uxfoundation.org; linux-doc@...r.kernel.org; linux-
> >> kernel@...r.kernel.org; Song, Xiongwei <Xiongwei.Song@...driver.com>
> >> Subject: Re: [RFC PATCH 2/3] mm/slub: unify all sl[au]b parameters with "slab_$param"
> >> 
> >> CAUTION: This email comes from a non Wind River email account!
> >> Do not click links or open attachments unless you recognize the sender and know the
> >> content is safe.
> >> 
> >> On Fri, Dec 01, 2023 at 11:15:04AM +0800, sxwjean@...com wrote:
> >> > From: Xiongwei Song <xiongwei.song@...driver.com>
> >> >
> >> > Since the SLAB allocator has been removed, so we need to clean up the
> >> > sl[au]b_$params. However, the "slab/SLAB" terms should be keep for
> >> > long-term rather than "slub/SLUB". Hence, we should use "slab_$param"
> >> > as the primary prefix, which is pointed out by Vlastimil Babka. For more
> >> > information please see [1].
> >> >
> >> > This patch is changing the following slab parameters
> >> > - slub_max_order
> >> > - slub_min_order
> >> > - slub_min_objects
> >> > - slub_debug
> >> > to
> >> > - slab_max_order
> >> > - slab_min_order
> >> > - slab_min_objects
> >> > - slab_debug
> >> > as the primary slab parameters in
> >> > Documentation/admin-guide/kernel-parameters.txt and source, and rename all
> >> > setup functions of them too. Meanwhile, "slub_$params" can also be passed
> >> > by command line, which is to keep backward compatibility. Also mark all
> >> > "slub_$params" as legacy.
> >> 
> >> *If* we do this, I think the old names need to be recognized, perhaps
> 
> Yes, they are already recognized by the patch.

Ah, sorry, I missed that. I didn't see it when I skimmed earlier.

> >> with a boot pr_warn() about their deprecation/renaming for several
> >> releases (likely across LTSes). I think it's not a good idea to
> >> wholesale rename these with no warning. That's going to cause a lot of
> >> surprises and broken userspace...
> > 
> > Oh, yes, that's a good idea. Will update.
> 
> I'd wait for a while with the warnings, no need to rush.

Better to start ASAP, yeah?

-- 
Kees Cook