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Subject: Re: [PATCH v3] kasan: add memory corruption identification for
 software tag-based mode
From:   Walter Wu <walter-zh.wu@mediatek.com>
To:     Andrey Ryabinin <aryabinin@virtuozzo.com>
CC:     Dmitry Vyukov <dvyukov@google.com>,
        Alexander Potapenko <glider@google.com>,
        Christoph Lameter <cl@linux.com>,
        Pekka Enberg <penberg@kernel.org>,
        David Rientjes <rientjes@google.com>,
        Joonsoo Kim <iamjoonsoo.kim@lge.com>,
        Matthias Brugger <matthias.bgg@gmail.com>,
        "Martin Schwidefsky" <schwidefsky@de.ibm.com>,
        Arnd Bergmann <arnd@arndb.de>,
        "Vasily Gorbik" <gor@linux.ibm.com>,
        Andrey Konovalov <andreyknvl@google.com>,
        "Jason A . Donenfeld" <Jason@zx2c4.com>,
        Miles Chen <miles.chen@mediatek.com>,
        kasan-dev <kasan-dev@googlegroups.com>,
        LKML <linux-kernel@vger.kernel.org>,
        Linux-MM <linux-mm@kvack.org>,
        Linux ARM <linux-arm-kernel@lists.infradead.org>,
        <linux-mediatek@lists.infradead.org>,
        wsd_upstream <wsd_upstream@mediatek.com>
Date:   Fri, 26 Jul 2019 21:19:24 +0800
In-Reply-To: <71df2bd5-7bc8-2c82-ee31-3f68c3b6296d@virtuozzo.com>
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On Fri, 2019-07-26 at 15:52 +0300, Andrey Ryabinin wrote:
> 
> On 7/26/19 3:28 PM, Walter Wu wrote:
> > On Fri, 2019-07-26 at 15:00 +0300, Andrey Ryabinin wrote:
> >>
> >
> >>>
> >>>
> >>> I remember that there are already the lists which you concern. Maybe we
> >>> can try to solve those problems one by one.
> >>>
> >>> 1. deadlock issue? cause by kmalloc() after kfree()?
> >>
> >> smp_call_on_cpu()
> > 
> >>> 2. decrease allocation fail, to modify GFP_NOWAIT flag to GFP_KERNEL?
> >>
> >> No, this is not gonna work. Ideally we shouldn't have any allocations there.
> >> It's not reliable and it hurts performance.
> >>
> > I dont know this meaning, we need create a qobject and put into
> > quarantine, so may need to call kmem_cache_alloc(), would you agree this
> > action?
> > 
> 
> How is this any different from what you have now?

I originally thought you already agreed the free-list(tag-based
quarantine) after fix those issue. If no allocation there, i think maybe
only move generic quarantine into tag-based kasan, but its memory
consumption is more bigger our patch. what do you think?