From: Pasha Tatashin <pasha.tatashin@soleen.com>
To: David Laight <David.Laight@aculab.com>
Cc: Matthew Wilcox <willy@infradead.org>,
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Subject: Re: [RFC 00/14] Dynamic Kernel Stacks
Date: Mon, 18 Mar 2024 12:57:32 -0400 [thread overview]
Message-ID: <CA+CK2bB59NUJ7c9-Akt_QnVujfg0bHukhtLgbMv-fDFwWDkgsA@mail.gmail.com> (raw)
In-Reply-To: <4b542b49b2994c9d8c4c73b9e3b42dde@AcuMS.aculab.com>
> I think you'll need to broadcast an invalidate.
> Consider:
> CPU A: task allocates extra pages and adds something to some list.
> CPU B: accesses that data and maybe modifies it.
> Some page-table walk setup ut the TLB.
> CPU A: task detects the modify, removes the item from the list,
> collapses back the stack and sleeps.
> Stack pages freed.
> CPU A: task wakes up (on the same cpu for simplicity).
> Goes down a deep stack and puts an item on a list.
> Different physical pages are allocated.
> CPU B: accesses the associated KVA.
> It better not have a cached TLB.
>
> Doesn't that need an IPI?
Yes, this is annoying. If we share a stack with another CPU, then get
a new stack, and share it again with another CPU we get in trouble.
Yet, IPI during context switch would kill the performance :-\
I wonder if there is a way to optimize this scenario like doing IPI
invalidation only after stack sharing?
Pasha
next prev parent reply other threads:[~2024-03-18 16:58 UTC|newest]
Thread overview: 98+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-03-11 16:46 [RFC 00/14] Dynamic Kernel Stacks Pasha Tatashin
2024-03-11 16:46 ` [RFC 01/14] task_stack.h: remove obsolete __HAVE_ARCH_KSTACK_END check Pasha Tatashin
2024-03-17 14:36 ` Christophe JAILLET
2024-03-17 15:13 ` Pasha Tatashin
2024-03-11 16:46 ` [RFC 02/14] fork: Clean-up ifdef logic around stack allocation Pasha Tatashin
2024-03-11 16:46 ` [RFC 03/14] fork: Clean-up naming of vm_strack/vm_struct variables in vmap stacks code Pasha Tatashin
2024-03-17 14:42 ` Christophe JAILLET
2024-03-19 16:32 ` Pasha Tatashin
2024-03-11 16:46 ` [RFC 04/14] fork: Remove assumption that vm_area->nr_pages equals to THREAD_SIZE Pasha Tatashin
2024-03-17 14:45 ` Christophe JAILLET
2024-03-17 15:14 ` Pasha Tatashin
2024-03-11 16:46 ` [RFC 05/14] fork: check charging success before zeroing stack Pasha Tatashin
2024-03-12 15:57 ` Kirill A. Shutemov
2024-03-12 16:52 ` Pasha Tatashin
2024-03-11 16:46 ` [RFC 06/14] fork: zero vmap stack using clear_page() instead of memset() Pasha Tatashin
2024-03-12 7:15 ` Nikolay Borisov
2024-03-12 16:53 ` Pasha Tatashin
2024-03-14 7:55 ` Christophe Leroy
2024-03-14 13:52 ` Pasha Tatashin
2024-03-17 14:48 ` Christophe JAILLET
2024-03-17 15:15 ` Pasha Tatashin
2024-03-11 16:46 ` [RFC 07/14] fork: use the first page in stack to store vm_stack in cached_stacks Pasha Tatashin
2024-03-11 16:46 ` [RFC 08/14] fork: separate vmap stack alloction and free calls Pasha Tatashin
2024-03-14 15:18 ` Jeff Xie
2024-03-14 17:14 ` Pasha Tatashin
2024-03-17 14:51 ` Christophe JAILLET
2024-03-17 15:15 ` Pasha Tatashin
2024-03-11 16:46 ` [RFC 09/14] mm/vmalloc: Add a get_vm_area_node() and vmap_pages_range_noflush() public functions Pasha Tatashin
2024-03-11 16:46 ` [RFC 10/14] fork: Dynamic Kernel Stacks Pasha Tatashin
2024-03-11 19:32 ` Randy Dunlap
2024-03-11 19:55 ` Pasha Tatashin
2024-03-11 16:46 ` [RFC 11/14] x86: add support for " Pasha Tatashin
2024-03-11 22:17 ` Andy Lutomirski
2024-03-11 23:10 ` Pasha Tatashin
2024-03-11 23:33 ` Thomas Gleixner
2024-03-11 23:34 ` Andy Lutomirski
2024-03-12 0:08 ` Pasha Tatashin
2024-03-12 0:23 ` Pasha Tatashin
2024-03-11 23:34 ` Dave Hansen
2024-03-11 23:41 ` Andy Lutomirski
2024-03-11 23:56 ` Nadav Amit
2024-03-12 0:02 ` Andy Lutomirski
2024-03-12 7:20 ` Nadav Amit
2024-03-12 0:53 ` Dave Hansen
2024-03-12 1:25 ` H. Peter Anvin
2024-03-12 2:16 ` Andy Lutomirski
2024-03-12 2:20 ` H. Peter Anvin
2024-03-12 21:58 ` Andi Kleen
2024-03-13 10:23 ` Thomas Gleixner
2024-03-13 13:43 ` Pasha Tatashin
2024-03-13 15:28 ` Pasha Tatashin
2024-03-13 16:12 ` Thomas Gleixner
2024-03-14 14:03 ` Pasha Tatashin
2024-03-14 18:26 ` Thomas Gleixner
2024-03-11 16:46 ` [RFC 12/14] task_stack.h: Clean-up stack_not_used() implementation Pasha Tatashin
2024-03-11 16:46 ` [RFC 13/14] task_stack.h: Add stack_not_used() support for dynamic stack Pasha Tatashin
2024-03-11 16:46 ` [RFC 14/14] fork: Dynamic Kernel Stack accounting Pasha Tatashin
2024-03-11 17:09 ` [RFC 00/14] Dynamic Kernel Stacks Mateusz Guzik
2024-03-11 18:58 ` Pasha Tatashin
2024-03-11 19:21 ` Mateusz Guzik
2024-03-11 19:55 ` Pasha Tatashin
2024-03-12 17:18 ` H. Peter Anvin
2024-03-12 19:45 ` Pasha Tatashin
2024-03-12 21:36 ` H. Peter Anvin
2024-03-14 19:05 ` Kent Overstreet
2024-03-14 19:23 ` Pasha Tatashin
2024-03-14 19:28 ` Kent Overstreet
2024-03-14 19:34 ` Pasha Tatashin
2024-03-14 19:49 ` Kent Overstreet
2024-03-12 22:18 ` David Laight
2024-03-14 19:43 ` Matthew Wilcox
2024-03-14 19:53 ` Kent Overstreet
2024-03-14 19:57 ` Matthew Wilcox
2024-03-14 19:58 ` Kent Overstreet
2024-03-15 3:13 ` Pasha Tatashin
2024-03-15 3:39 ` H. Peter Anvin
2024-03-16 19:17 ` Pasha Tatashin
2024-03-17 0:41 ` Matthew Wilcox
2024-03-17 1:32 ` Kent Overstreet
2024-03-17 14:19 ` Pasha Tatashin
2024-03-17 14:43 ` Brian Gerst
2024-03-17 16:15 ` Pasha Tatashin
2024-03-17 21:30 ` Brian Gerst
2024-03-18 14:59 ` Pasha Tatashin
2024-03-18 21:02 ` Brian Gerst
2024-03-19 14:56 ` Pasha Tatashin
2024-03-17 18:57 ` David Laight
2024-03-18 15:09 ` Pasha Tatashin
2024-03-18 15:13 ` Pasha Tatashin
2024-03-18 15:19 ` Matthew Wilcox
2024-03-18 15:30 ` Pasha Tatashin
2024-03-18 15:53 ` David Laight
2024-03-18 16:57 ` Pasha Tatashin [this message]
2024-03-18 15:38 ` David Laight
2024-03-18 17:00 ` Pasha Tatashin
2024-03-18 17:37 ` Pasha Tatashin
2024-03-15 4:17 ` H. Peter Anvin
2024-03-17 0:47 ` H. Peter Anvin
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