linux-kernel - Re: [PATCH v4 17/45] init: kmsan: call KMSAN initialization routines

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Message-ID: <CAG_fn=ViHiYCWj0jmm1R=gSX0880-rQ-CA3VaEjiLnGkDN1G4w@mail.gmail.com>
Date:   Tue, 2 Aug 2022 22:07:42 +0200
From:   Alexander Potapenko <glider@...gle.com>
To:     Marco Elver <elver@...gle.com>
Cc:     Alexander Viro <viro@...iv.linux.org.uk>,
        Alexei Starovoitov <ast@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Andrey Konovalov <andreyknvl@...gle.com>,
        Andy Lutomirski <luto@...nel.org>,
        Arnd Bergmann <arnd@...db.de>, Borislav Petkov <bp@...en8.de>,
        Christoph Hellwig <hch@....de>,
        Christoph Lameter <cl@...ux.com>,
        David Rientjes <rientjes@...gle.com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Eric Dumazet <edumazet@...gle.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        Ilya Leoshkevich <iii@...ux.ibm.com>,
        Ingo Molnar <mingo@...hat.com>, Jens Axboe <axboe@...nel.dk>,
        Joonsoo Kim <iamjoonsoo.kim@....com>,
        Kees Cook <keescook@...omium.org>,
        Mark Rutland <mark.rutland@....com>,
        Matthew Wilcox <willy@...radead.org>,
        "Michael S. Tsirkin" <mst@...hat.com>,
        Pekka Enberg <penberg@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Petr Mladek <pmladek@...e.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Vasily Gorbik <gor@...ux.ibm.com>,
        Vegard Nossum <vegard.nossum@...cle.com>,
        Vlastimil Babka <vbabka@...e.cz>,
        kasan-dev <kasan-dev@...glegroups.com>,
        Linux Memory Management List <linux-mm@...ck.org>,
        Linux-Arch <linux-arch@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v4 17/45] init: kmsan: call KMSAN initialization routines

On Tue, Jul 12, 2022 at 4:05 PM Marco Elver <elver@...gle.com> wrote:
>

> > +/**
> > + * kmsan_task_exit() - Notify KMSAN that a task has exited.
> > + * @task: task about to finish.
> > + */
> > +void kmsan_task_exit(struct task_struct *task);
>
> Something went wrong with patch shuffling here I think,
> kmsan_task_create + kmsan_task_exit decls are duplicated by this
> patch.
Right, I've messed it up. Will fix.

> > +
> > +struct page_pair {
>
> 'struct shadow_origin_pages' for a more descriptive name?
How about "metadata_page_pair"?

> > + * At the very end there may be leftover blocks in held_back[]. They are
> > + * collected later by kmsan_memblock_discard().
> > + */
> > +bool kmsan_memblock_free_pages(struct page *page, unsigned int order)
> > +{
> > +       struct page *shadow, *origin;
>
> Can this just be 'struct page_pair'?

Not sure this is worth it. We'll save one line by assigning this
struct to held_back[order], but the call to kmsan_setup_meta() will
become more verbose.
(and passing a struct page_pair to kmsan_setup_meta() looks excessive).


> > +                     struct page *origin, int order)
> > +{
> > +       int i;
> > +
> > +       for (i = 0; i < (1 << order); i++) {
>
> Noticed this in many places, but we can just make these "for (int i =.." now.
Fixed here and all over the runtime.

> > @@ -1731,6 +1731,9 @@ void __init memblock_free_pages(struct page *page, unsigned long pfn,
> >  {
> >         if (early_page_uninitialised(pfn))
> >                 return;
> > +       if (!kmsan_memblock_free_pages(page, order))
> > +               /* KMSAN will take care of these pages. */
> > +               return;
>
> Add {} because the then-statement is not right below the if.

Done.

-- 
Alexander Potapenko
Software Engineer

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