From: Jens Axboe <axboe@kernel.dk>
To: Peter Zijlstra <peterz@infradead.org>
Cc: io-uring@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, tglx@kernel.org, mingo@redhat.com
Subject: Re: [PATCH 04/15] x86: implement thread identity handoff
Date: Mon, 14 Sep 2026 08:00:41 -0600 [thread overview]
Message-ID: <73837a51-e163-4b4e-8be2-4cdc044393b8@kernel.dk> (raw)
In-Reply-To: <20260914114656.GC3500130@noisy.programming.kicks-ass.net>
On 9/14/26 5:46 AM, Peter Zijlstra wrote:
> On Fri, Sep 11, 2026 at 09:40:54AM -0600, Jens Axboe wrote:
>
>> +/* state bound to the task that neither side may have */
>> +static bool thread_handoff_task_ok(struct task_struct *tsk)
>> +{
>> + /* I/O permissions, the bitmap hangs off the task */
>> + if (test_tsk_thread_flag(tsk, TIF_IO_BITMAP) || tsk->thread.iopl_emul)
>> + return false;
>> +#ifdef CONFIG_X86_USER_SHADOW_STACK
>> + /* the shadow stack is per-thread and would have to move along */
>> + if (tsk->thread.features & ARCH_SHSTK_SHSTK)
>> + return false;
>> +#endif
>
> Distributions are having this enabled, this means nobody will pass this
> check.
Ah good point, should be feasible just by swapping s->shstk,
s->features, and s->features_locked. Traveling right now, but I'll test
that for the next version.
--
Jens Axboe
next prev parent reply other threads:[~2026-09-14 14:00 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-11 15:40 [RFC PATCH 00/15] io_uring: thread identity handoff for blocking inline issue Jens Axboe
2026-09-11 15:40 ` [PATCH 01/15] kernel: add thread identity handoff Jens Axboe
2026-09-11 15:40 ` [PATCH 02/15] sched: call into io_uring when a PF_IO_HANDOFF task blocks Jens Axboe
2026-09-11 15:40 ` [PATCH 03/15] arm64: implement thread identity handoff Jens Axboe
2026-09-11 15:40 ` [PATCH 04/15] x86: " Jens Axboe
2026-09-14 11:46 ` Peter Zijlstra
2026-09-14 14:00 ` Jens Axboe [this message]
2026-09-11 15:40 ` [PATCH 05/15] io_uring/kbuf: use io_ring_submit_unlock() helper Jens Axboe
2026-09-11 15:40 ` [PATCH 06/15] io_uring: keep the tctx nodes on a list Jens Axboe
2026-09-11 15:40 ` [PATCH 07/15] io_uring: add uring_lock section depth tracking and blockable opdef flag Jens Axboe
2026-09-11 15:40 ` [PATCH 08/15] io_uring: split io_uring_enter() and io_submit_sqes() into helpers Jens Axboe
2026-09-11 15:40 ` [PATCH 09/15] io_uring: keep the submission plug on the io_submit_sqes() stack Jens Axboe
2026-09-11 15:41 ` [PATCH 10/15] io-wq: support handing a task identity to an idle worker Jens Axboe
2026-09-11 15:41 ` [PATCH 11/15] io_uring: enable handing submitter identity to an io-wq worker Jens Axboe
2026-09-11 15:41 ` [PATCH 12/15] io_uring: defer the identity migration to the end of the submission Jens Axboe
2026-09-11 15:41 ` [PATCH 13/15] io_uring: issue blockable requests inline in blocking mode Jens Axboe
2026-09-11 15:41 ` [PATCH 14/15] io_uring: add tracepoints for the handoff operation Jens Axboe
2026-09-11 15:41 ` [PATCH 15/15] io_uring: issue IOSQE_ASYNC requests inline when a handoff is possible Jens Axboe
2026-09-11 17:33 ` [RFC PATCH 00/15] io_uring: thread identity handoff for blocking inline issue Gabriel Krisman Bertazi
2026-09-11 17:51 ` Jens Axboe
2026-09-14 19:22 ` Peter Zijlstra
2026-09-14 23:27 ` Jens Axboe
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