Date: Fri, 2 Sep 2022 17:17:04 +0300 From: Konstantin Belousov <kostikbel@gmail.com> To: Mateusz Guzik <mjguzik@gmail.com> Cc: freebsd-current@freebsd.org Subject: Re: kernel-side thread stack swapping Message-ID: <YxIQYCb3CsBtv9Gf@kib.kiev.ua> In-Reply-To: <CAGudoHGbomDGPNsYa_RHGS7NkWU4iOBHnxr9bCnvfn8BYMjEJQ@mail.gmail.com> References: <CAGudoHFh5H721kcQT0zDdErD%2Bj%2B0YA6Hz=%2Bjarg9R1jdttfx-A@mail.gmail.com> <YxINyjnFDt8kU41j@kib.kiev.ua> <CAGudoHGbomDGPNsYa_RHGS7NkWU4iOBHnxr9bCnvfn8BYMjEJQ@mail.gmail.com>
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On Fri, Sep 02, 2022 at 04:11:40PM +0200, Mateusz Guzik wrote: > On 9/2/22, Konstantin Belousov <kostikbel@gmail.com> wrote: > > On Fri, Sep 02, 2022 at 02:05:37PM +0200, Mateusz Guzik wrote: > >> Is this really of practical use today? > >> > >> I have a WIP patch which needs to temporarily store something on the > >> stack and should things go wrong enough it will be accessed by UMA, > >> which can't handle the fault nor decide to skip the access. > >> > >> I can add something like td_pinstack or whatever to keep it around, > >> but perhaps the entire machinery can be just whacked? > > p_hold already does that. > > > > I only need to protect the one stack and more importantly don't want > to take the proc lock to bump p_hold (nor convert it to atomics), it's > all thread-local so to speak. You do not want to take proc lock, or cannot? Note that only sleeping thread' stack can be swapped out.home | help
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