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From:   Dmitry Vyukov <dvyukov@google.com>
Date:   Mon, 24 Sep 2018 17:18:25 +0200
Message-ID: <CACT4Y+ayX8vzd2JPrLeFhf3K_Quf4x6SDtmtkNJuwNLyOh67tQ@mail.gmail.com>
Subject: Re: WARNING: kmalloc bug in input_mt_init_slots
To:     Christopher Lameter <cl@linux.com>
Cc:     Dmitry Torokhov <dmitry.torokhov@gmail.com>,
        syzbot+87829a10073277282ad1@syzkaller.appspotmail.com,
        Pekka Enberg <penberg@kernel.org>,
        "linux-input@vger.kernel.org" <linux-input@vger.kernel.org>,
        lkml <linux-kernel@vger.kernel.org>,
        Henrik Rydberg <rydberg@bitmath.org>,
        syzkaller-bugs <syzkaller-bugs@googlegroups.com>,
        Linux-MM <linux-mm@kvack.org>
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On Mon, Sep 24, 2018 at 5:08 PM, Christopher Lameter <cl@linux.com> wrote:
> On Sun, 23 Sep 2018, Dmitry Vyukov wrote:
>
>> What was the motivation behind that WARNING about large allocations in
>> kmalloc? Why do we want to know about them? Is the general policy that
>> kmalloc calls with potentially large size requests need to use NOWARN?
>> If this WARNING still considered useful? Or we should change it to
>> pr_err?
>
> In general large allocs should be satisfied by the page allocator. The
> slab allocators are used for allocating and managing small objects. The
> page allocator has mechanisms to deal with large objects (compound pages,
> multiple page sized allocs etc).

I am asking more about the status of this warning. If it fires in
input_mt_init_slots(), does it mean that input_mt_init_slots() needs
to be fixed? If not, then we need to change this warning to something
else.