From: David Matlack <dmatlack@google.com>
To: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: akpm@linux-foundation.org, brauner@kernel.org, corbet@lwn.net,
graf@amazon.com, jgg@ziepe.ca, linux-kernel@vger.kernel.org,
linux-kselftest@vger.kernel.org, linux-mm@kvack.org,
masahiroy@kernel.org, ojeda@kernel.org, pratyush@kernel.org,
rdunlap@infradead.org, rppt@kernel.org, tj@kernel.org,
jasonmiu@google.com, skhawaja@google.com
Subject: Re: [PATCH v3 2/3] liveupdate: kho: Increase metadata bitmap size to PAGE_SIZE
Date: Mon, 27 Oct 2025 15:44:19 -0700 [thread overview]
Message-ID: <CALzav=cprjK-WutXYKii28e37R=F7jPZfA5_=_Qh4HH5p2Um=A@mail.gmail.com> (raw)
In-Reply-To: <20251021000852.2924827-3-pasha.tatashin@soleen.com>
On Mon, Oct 20, 2025 at 5:09 PM Pasha Tatashin
<pasha.tatashin@soleen.com> wrote:
>
> KHO memory preservation metadata is preserved in 512 byte chunks which
> requires their allocation from slab allocator. Slabs are not safe to be
> used with KHO because of kfence, and because partial slabs may lead
> leaks to the next kernel. Change the size to be PAGE_SIZE.
> -#define PRESERVE_BITS (512 * 8)
> +#define PRESERVE_BITS (PAGE_SIZE * 8)
nit: A comment somewhere (maybe here?) about the requirement that KHO
metadata are not stored on slabs would be helpful to avoid someone
"optimizing" this back to 512 in the future.
next prev parent reply other threads:[~2025-10-27 22:44 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-10-21 0:08 [PATCH v3 0/3] KHO: kfence + KHO memory corruption fix Pasha Tatashin
2025-10-21 0:08 ` [PATCH v3 1/3] liveupdate: kho: warn and fail on metadata or preserved memory in scratch area Pasha Tatashin
2025-10-22 10:22 ` Pratyush Yadav
2025-10-27 22:29 ` David Matlack
2025-10-28 0:01 ` Pasha Tatashin
2025-10-29 16:09 ` Jason Gunthorpe
2025-10-29 8:48 ` Mike Rapoport
2025-10-29 22:22 ` Pasha Tatashin
2025-10-29 22:35 ` Andrew Morton
2025-10-21 0:08 ` [PATCH v3 2/3] liveupdate: kho: Increase metadata bitmap size to PAGE_SIZE Pasha Tatashin
2025-10-22 10:25 ` Pratyush Yadav
2025-10-27 22:44 ` David Matlack [this message]
2025-10-27 22:56 ` David Matlack
2025-10-27 23:01 ` David Matlack
2025-10-28 0:03 ` Pasha Tatashin
2025-10-21 0:08 ` [PATCH v3 3/3] liveupdate: kho: allocate metadata directly from the buddy allocator Pasha Tatashin
2025-10-27 23:04 ` David Matlack
2025-10-28 0:03 ` Pasha Tatashin
2025-10-21 6:00 ` [PATCH v3 0/3] KHO: kfence + KHO memory corruption fix Mike Rapoport
2025-10-21 16:04 ` Pasha Tatashin
2025-10-21 20:53 ` Andrew Morton
2025-10-22 0:15 ` Pasha Tatashin
2025-10-22 5:48 ` Mike Rapoport
2025-10-22 18:24 ` Andrew Morton
2025-10-23 2:45 ` Andrew Morton
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