From: Harry Yoo <harry@kernel.org>
To: "Vlastimil Babka (SUSE)" <vbabka@kernel.org>
Cc: Sang-Heon Jeon <ekffu200098@gmail.com>,
Andrew Morton <akpm@linux-foundation.org>,
Christoph Lameter <cl@gentwo.org>,
David Rientjes <rientjes@google.com>, Hao Li <hao.li@linux.dev>,
linux-mm@kvack.org, Roman Gushchin <roman.gushchin@linux.dev>
Subject: Re: [PATCH v2] mm/slub: clamp slab_min_order to MAX_PAGE_ORDER
Date: Mon, 12 Oct 2026 15:09:31 +0100 [thread overview]
Message-ID: <aszp31zqP607YL18@thinkstation> (raw)
In-Reply-To: <5895ceec-df6a-4604-a7b9-8138212d786f@kernel.org>
On Mon, Oct 12, 2026 at 10:23:16AM +0200, Vlastimil Babka (SUSE) wrote:
> On 10/11/26 03:48, Sang-Heon Jeon wrote:
> > setup_slub_max_order() clamps slab_max_order to MAX_PAGE_ORDER, but
> > setup_slub_min_order() has no such clamp.
> >
> > The buddy allocator cannot allocate more than 2^MAX_PAGE_ORDER pages
> > at once, so slab_min_order above it makes no sense.
> >
> > If slab_min_order is set above MAX_PAGE_ORDER, it can even panic at
> > boot or invoke undefined behavior in order_objects().
> >
> > So clamp slab_min_order to MAX_PAGE_ORDER as well.
> >
> > Fixes: 81819f0fc828 ("SLUB core")
> > Signed-off-by: Sang-Heon Jeon <ekffu200098@gmail.com>
>
> Hi,
>
> this is effectively part of my bigger refactor here:
Ouch, I missed that point!
> https://lore.kernel.org/linux-mm/20260923-slub_tiny_rework-v1-1-a0e66d536eb5@kernel.org/
Looking forward to seeing further updates on this ...
(and hopefully do more review)
--
Cheers,
Harry / Hyeonggon
prev parent reply other threads:[~2026-10-12 14:09 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-11 1:48 [PATCH v2] mm/slub: clamp slab_min_order to MAX_PAGE_ORDER Sang-Heon Jeon
2026-10-12 8:23 ` Vlastimil Babka (SUSE)
2026-10-12 13:21 ` Sang-Heon Jeon
2026-10-12 14:09 ` Harry Yoo [this message]
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