linux-kernel - Re: [PATCH v2 2/5] lib: add error_report_notify to collect debugging tools' reports

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Message-ID: <CAG_fn=XEe_ptR718exopJoEVUKgOd5SfaHev_PbW=aq4z8HEtQ@mail.gmail.com>
Date:   Mon, 18 Jan 2021 14:14:16 +0100
From:   Alexander Potapenko <glider@...gle.com>
To:     Petr Mladek <pmladek@...e.com>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Andrey Konovalov <andreyknvl@...gle.com>,
        Dmitriy Vyukov <dvyukov@...gle.com>,
        Ingo Molnar <mingo@...hat.com>, Marco Elver <elver@...gle.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        Linux Memory Management List <linux-mm@...ck.org>
Subject: Re: [PATCH v2 2/5] lib: add error_report_notify to collect debugging
 tools' reports

> > > +
> > > +     /* Pairs with acquire in last_report_show(). */
> > > +     atomic_inc_return_release(&num_reports);
> > > +     schedule_delayed_work(&reporting_done, 0);
> >
> > Why delayed work when it gets queued immediately?
>
> Because error reports may be sent from a place where waiting is
> forbidden (in the case of KFENCE that is the page fault handler).
> A delayed work ensures the notification occurs in a wait-safe context.
>
Agreed, there's actually no point in calling schedule_delayed_work()
instead of schedule_work() here.