linux-kernel - Re: [PATCH 34/40] lib: code tagging context capture support

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Date:   Wed, 3 May 2023 12:45:29 -0700
From:   Suren Baghdasaryan <surenb@...gle.com>
To:     Dave Hansen <dave.hansen@...el.com>
Cc:     Michal Hocko <mhocko@...e.com>, akpm@...ux-foundation.org,
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Subject: Re: [PATCH 34/40] lib: code tagging context capture support

On Wed, May 3, 2023 at 8:26 AM Dave Hansen <dave.hansen@...el.com> wrote:
>
> On 5/3/23 08:18, Suren Baghdasaryan wrote:
> >>> +static inline void rem_ctx(struct codetag_ctx *ctx,
> >>> +                        void (*free_ctx)(struct kref *refcount))
> >>> +{
> >>> +     struct codetag_with_ctx *ctc = ctx->ctc;
> >>> +
> >>> +     spin_lock(&ctc->ctx_lock);
> >> This could deadlock when allocator is called from the IRQ context.
> > I see. spin_lock_irqsave() then?
>
> Yes.  But, even better, please turn on lockdep when you are testing.  It
> will find these for you.  If you're on x86, we have a set of handy-dandy
> debug options that you can add to an existing config with:
>
>         make x86_debug.config

Nice!
I thought I tested with lockdep enabled but I might be wrong. The
beauty of working on multiple patchsets in parallel is that I can't
remember what I did for each one :)

>
> That said, I'm as concerned as everyone else that this is all "new" code
> and doesn't lean on existing tracing or things like PAGE_OWNER enough.

Yeah, that's being actively discussed.

>