Subject: Re: [REGRESSION] rseq: refactoring in v6.19 broke everyone on arm64 and tcmalloc everywhere

From: Thomas Gleixner <[email-masked]>
Date: Tue, 28 Apr 2026 17:46:44 +0200

On Tue, Apr 28 2026 at 15:31, Mathias Stearn wrote:
> On Tue, Apr 28, 2026 at 11:54 AM Dmitry Vyukov <[email-masked]> wrote:
>>
>> On Tue, 28 Apr 2026 at 10:18, Thomas Gleixner <[email-masked]> wrote:
>> >
>> > Is there a pre-compiled version of those tcmalloc tests somewhere?
>>
>> I've attached an archive with 2 tests that I used.
>
> Here is an additional test. It is the stress test I used to show that
> it could result in two live allocations getting the same address. It
> will run for up to a minute or until the first double allocation gets
> detected (usually within 30ms on 6.19).

Thanks to both of you for providing those binaries.

I've run all three binaries now on my latest version in parallel for
quite same time and it seems to hold up. Mark just told me privately
that these plus the arm64 fix he's working on survive that double
allocation test.

Let me go and write a cover letter and post the pile.

Thanks,

        tglx