From: Thomas Gleixner <tglx@kernel.org>
To: "H. Peter Anvin" <hpa@zytor.com>, David Stevens <stevensd@google.com>
Cc: 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 12/13] x86: Add support for dynamic kernel stacks via FRED
Date: Mon, 29 Jun 2026 10:41:13 +0200 [thread overview]
Message-ID: <878q7xspqu.ffs@fw13> (raw)
In-Reply-To: <888C322E-BF59-4C72-BFD2-2E71FD8605C0@zytor.com>
On Sun, Jun 28 2026 at 13:33, H. Peter Anvin wrote:
> On June 28, 2026 9:46:32 AM PDT, Thomas Gleixner <tglx@kernel.org> wrote:
>>> That sort of fault would probably end up either with a
>>> page_fault_oops() or risk a context switch with SL>0, but we shouldn't
>>> make debugging harder with UB.
>>
>>Definitely not :)
>>
>>You can avoid quite some of the problems right in the ASM entry code.
>>Instead of checking event type/vector and then going to the stack switch
>>logic, you can check the stack level on which the event happened
>>first. If it's not 0, then there is nothing to do.
>>
>>
>
> To be fair, for this *specific* case, memmove() does exist for a reason :)
It does, but why bother doing actual work, if you know upfront that it's
not required :)
next prev parent reply other threads:[~2026-06-29 8:41 UTC|newest]
Thread overview: 59+ 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 [this message]
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
2026-06-25 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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