From: Linus Torvalds <torvalds@linux-foundation.org>
To: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Harry Yoo <harry.yoo@oracle.com>,
David Rientjes <rientjes@google.com>,
Christoph Lameter <cl@gentwo.org>,
Roman Gushchin <roman.gushchin@linux.dev>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
LKML <linux-kernel@vger.kernel.org>,
Christoph Hellwig <hch@infradead.org>
Subject: Re: [GIT PULL] slab fix for 6.18-rc7
Date: Thu, 20 Nov 2025 10:58:13 -0800 [thread overview]
Message-ID: <CAHk-=whUBuZmRNGCxjnAkFQLO_HVV8SgWEAUg+3z4EARD9MM3Q@mail.gmail.com> (raw)
In-Reply-To: <3f4ec3be-0725-43cc-a75b-72549ebdc5c9@suse.cz>
On Thu, 20 Nov 2025 at 10:45, Vlastimil Babka <vbabka@suse.cz> wrote:
>
> * Fix mempool poisoning order>0 pages with CONFIG_HIGHMEM (Vlastimil Babka)
I've pulled this, but honestly, CONFIG_HIGHMEM should be considered a
dying breed, and I'd have been happier with just not adding extra code
for that thing.
Seriously, CONFIG_HIGHMEM is legacy x86 computers and embedded - old -
arm stuff. Fixing debug code for this is simply not worth it. Nobody
does actual kernel debugging on those platforms.
It already skips poisoning for *much* more important cases, I really
think the whole CONFIG_SLUB_DEBUG_ON could have been conditional on
!CONFIG_HIGHMEM.
In fact, not just SLUB_DEBUG_ON. I suspect *all* of SLUB_DEBUG could
be disabled for non-highmem cases, but I guess that right now it's
only CONFIG_SLUB_DEBUG_ON that triggers this situation anyway.
We will literally get rid of CONFIG_HIGHMEM entirely at some point,
but before we finally get to that point, I think we might as well at
least limit the pain. Because HIGHMEM has always been just that: pain.
Let's not add to it any more.
Linus
next prev parent reply other threads:[~2025-11-20 18:58 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-11-20 18:45 Vlastimil Babka
2025-11-20 18:58 ` Linus Torvalds [this message]
2025-11-20 20:11 ` Matthew Wilcox
2025-11-20 21:37 ` Linus Torvalds
2025-11-20 21:55 ` Linus Torvalds
2025-11-20 19:00 ` pr-tracker-bot
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