linux-kernel - Re: [PATCH] kmemleak: Increase maximum early log entries to 1000000

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Date:   Tue, 30 Jul 2019 08:22:21 -0700
From:   Nicolas Boichat <drinkcat@...omium.org>
To:     Andrey Ryabinin <aryabinin@...tuozzo.com>
Cc:     Dmitry Vyukov <dvyukov@...gle.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Masahiro Yamada <yamada.masahiro@...ionext.com>,
        Kees Cook <keescook@...omium.org>,
        Petr Mladek <pmladek@...e.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>,
        Joe Lawrence <joe.lawrence@...hat.com>,
        Sri Krishna chowdary <schowdary@...dia.com>,
        Uladzislau Rezki <urezki@...il.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Changbin Du <changbin.du@...el.com>,
        LKML <linux-kernel@...r.kernel.org>,
        Stephen Rothwell <sfr@...b.auug.org.au>,
        Catalin Marinas <catalin.marinas@....com>
Subject: Re: [PATCH] kmemleak: Increase maximum early log entries to 1000000

On Wed, Jul 24, 2019 at 2:01 AM Andrey Ryabinin <aryabinin@...tuozzo.com> wrote:
>
>
>
> On 7/23/19 11:13 AM, Nicolas Boichat wrote:
> > On Tue, Jul 23, 2019 at 3:46 PM Dmitry Vyukov <dvyukov@...gle.com> wrote:
> >>
> >> On Tue, Jul 23, 2019 at 9:26 AM Nicolas Boichat <drinkcat@...omium.org> wrote:
> >>>
> >>> When KASan is enabled, a lot of memory is allocated early on,
> >>> and kmemleak complains (this is on a 4GB RAM system):
> >>> kmemleak: Early log buffer exceeded (129846), please increase
> >>>   DEBUG_KMEMLEAK_EARLY_LOG_SIZE
> >>>
> >>> Let's increase the upper limit to 1M entry. That would take up
> >>> 160MB of RAM at init (each early_log entry is 160 bytes), but
> >>> the memory would later be freed (early_log is __initdata).
> >>
> >> Interesting. Is it on an arm64 system?
> >
> > Yes arm64. And this is chromiumos-4.19 tree. I didn't try to track
> > down where these allocations come from...
> >
>
> Is this still a problem in upstream tree? 4.19 doesn't have fed84c785270 ("mm/memblock.c: skip kmemleak for kasan_init()")

Sorry for the delay, and thanks for the hint, indeed, not a problem
with that patch backported to our 4.19 tree: the number of allocations
shrinks from 100K+ to 1K+.

However, I think Dmitry is still right that the default (400) is too
low, I will send a patch for that.