From: Matthew Wilcox <willy@infradead.org>
To: Dave Hansen <dave.hansen@intel.com>
Cc: Thomas Gleixner <tglx@kernel.org>,
Zach O'Keefe <zokeefe@google.com>,
"H. Peter Anvin" <hpa@zytor.com>,
David Stevens <stevensd@google.com>,
Pasha Tatashin <pasha.tatashin@soleen.com>,
Linus Walleij <linus.walleij@linaro.org>,
Will Deacon <willdeacon@google.com>,
Quentin Perret <qperret@google.com>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
x86@kernel.org, Andy Lutomirski <luto@kernel.org>,
Xin Li <xin@zytor.com>, Peter Zijlstra <peterz@infradead.org>,
Andrew Morton <akpm@linux-foundation.org>,
David Hildenbrand <david@kernel.org>,
Lorenzo Stoakes <ljs@kernel.org>,
"Liam R. Howlett" <Liam.Howlett@oracle.com>,
Vlastimil Babka <vbabka@kernel.org>,
Mike Rapoport <rppt@kernel.org>,
Suren Baghdasaryan <surenb@google.com>,
Michal Hocko <mhocko@suse.com>,
Uladzislau Rezki <urezki@gmail.com>, Kees Cook <kees@kernel.org>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH v2 00/13] Dynamic Kernel Stacks
Date: Mon, 29 Jun 2026 21:17:39 +0100 [thread overview]
Message-ID: <akLS44JGF59hh6aN@casper.infradead.org> (raw)
In-Reply-To: <5604a47b-9457-4162-bd23-720e29cf1983@intel.com>
On Mon, Jun 29, 2026 at 09:02:08AM -0700, Dave Hansen wrote:
> It could be done with really little overhead if the vmalloc()'d stacks
> set Accessed=0 on their PTEs and then checked them near vfree(). The
> PTEs are already getting touched there, so the cachelines should be hot
> anyway.
>
> The granularity would only be 4k, but it would be so cheap that we could
> turn it on universally. It would also be 100% deterministic.
>
> There are, of course, more games that could be played with stack depth
> checks on normal interrupts or NMIs. But those would be less deterministic.
I mean, if we just memset64() the whole stack to 0x535441434b544f50 and
then searched the stack for the lowest word that wasn't that value at
process exit, we'd get a much more granular idea with vanishingly few
false positives.
next prev parent reply other threads:[~2026-06-29 20:18 UTC|newest]
Thread overview: 71+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-04-24 19:14 [PATCH v2 00/13] Dynamic Kernel Stacks David Stevens
2026-04-24 19:14 ` [PATCH v2 01/13] fork: Remove assumption that vm_area->nr_pages equals to THREAD_SIZE David Stevens
2026-04-24 19:14 ` [PATCH v2 02/13] fork: Don't assume fully populated stack during reuse David Stevens
2026-04-24 19:14 ` [PATCH v2 03/13] fork: Move vm_stack to the beginning of the stack David Stevens
2026-04-24 19:14 ` [PATCH v2 04/13] fork: separate vmap stack allocation and free calls David Stevens
2026-04-24 19:14 ` [PATCH v2 05/13] mm/vmalloc: Add a get_vm_area_node() and vmap_pages_range() public functions David Stevens
2026-04-24 19:14 ` [PATCH v2 06/13] fork: Move vmap stack freeing to work queue David Stevens
2026-04-24 19:14 ` [PATCH v2 07/13] fork: Dynamic Kernel Stacks David Stevens
2026-04-24 19:14 ` [PATCH v2 08/13] task_stack.h: Add stack_not_used() support for dynamic stack David Stevens
2026-04-24 19:14 ` [PATCH v2 09/13] fork: Dynamic Kernel Stack accounting David Stevens
2026-04-24 19:14 ` [PATCH v2 10/13] fork: Store task pointer in unpopulated stack ptes David Stevens
2026-06-26 22:46 ` Thomas Gleixner
2026-06-27 23:11 ` Thomas Gleixner
2026-04-24 19:14 ` [PATCH v2 11/13] x86/entry/fred: encode frame pointer on entry David Stevens
2026-05-20 22:24 ` David Stevens
2026-05-22 22:25 ` H. Peter Anvin
2026-05-24 18:22 ` Xin Li
2026-04-24 19:14 ` [PATCH v2 12/13] x86: Add support for dynamic kernel stacks via FRED David Stevens
2026-06-26 22:39 ` Thomas Gleixner
2026-06-27 4:05 ` David Stevens
2026-06-28 16:46 ` Thomas Gleixner
2026-06-28 20:33 ` H. Peter Anvin
2026-06-29 8:41 ` Thomas Gleixner
2026-06-29 14:52 ` H. Peter Anvin
2026-06-30 8:28 ` Thomas Gleixner
2026-04-24 19:14 ` [PATCH v2 13/13] x86: Add support for dynamic kernel stacks via IST David Stevens
2026-04-24 19:41 ` [PATCH v2 00/13] Dynamic Kernel Stacks Dave Hansen
2026-04-24 21:35 ` Pasha Tatashin
2026-04-24 22:21 ` Dave Hansen
2026-04-24 22:49 ` David Stevens
2026-04-24 22:26 ` David Laight
2026-04-24 23:06 ` Pasha Tatashin
2026-06-19 0:29 ` Dave Hansen
2026-06-19 19:56 ` Zach O'Keefe
2026-06-20 5:25 ` David Stevens
2026-06-20 23:22 ` Dave Hansen
2026-04-25 9:19 ` H. Peter Anvin
2026-04-27 16:17 ` Dave Hansen
2026-06-18 14:50 ` Zach O'Keefe
2026-06-18 18:53 ` Dave Hansen
2026-06-18 22:28 ` H. Peter Anvin
2026-06-19 0:40 ` David Stevens
2026-06-19 0:44 ` H. Peter Anvin
2026-06-19 12:45 ` Thomas Gleixner
2026-06-19 19:20 ` Zach O'Keefe
2026-06-19 21:59 ` Thomas Gleixner
2026-06-20 5:02 ` David Stevens
2026-06-20 21:59 ` Thomas Gleixner
2026-06-20 19:33 ` Zach O'Keefe
2026-06-20 19:44 ` H. Peter Anvin
2026-06-20 20:01 ` Zach O'Keefe
2026-06-20 23:34 ` Thomas Gleixner
2026-06-22 23:00 ` Zach O'Keefe
2026-06-23 7:50 ` David Hildenbrand (Arm)
2026-06-23 9:10 ` David Laight
2026-06-23 9:19 ` David Hildenbrand (Arm)
2026-06-23 21:58 ` Thomas Gleixner
2026-06-29 16:02 ` Dave Hansen
2026-06-29 16:12 ` H. Peter Anvin
2026-06-29 16:18 ` Vlastimil Babka (SUSE)
2026-06-29 16:21 ` H. Peter Anvin
2026-06-29 17:29 ` Zach O'Keefe
2026-06-29 17:38 ` Dave Hansen
2026-06-29 19:43 ` David Laight
2026-06-29 20:17 ` Matthew Wilcox [this message]
2026-06-29 21:13 ` Dave Hansen
2026-06-29 20:28 ` David Laight
2026-06-25 11:56 ` Andrew Cooper
2026-06-25 21:38 ` H. Peter Anvin
2026-06-26 8:16 ` David Laight
2026-04-27 16:31 ` Pasha Tatashin
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