netdev - Re: [PATCH net] mld: fix panic in mld

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Message-ID: <CAMArcTXGbLdEjHZa0C25+WdDfxAM9kO5HKeYb47r0K7B+G121w@mail.gmail.com>
Date:   Mon, 28 Dec 2020 11:20:02 +0900
From:   Taehee Yoo <ap420073@...il.com>
To:     Cong Wang <xiyou.wangcong@...il.com>
Cc:     David Miller <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Linux Kernel Network Developers <netdev@...r.kernel.org>,
        Eric Dumazet <eric.dumazet@...il.com>
Subject: Re: [PATCH net] mld: fix panic in mld_newpack()

On Mon, 28 Dec 2020 at 04:24, Cong Wang <xiyou.wangcong@...il.com> wrote:
>
> On Sun, Dec 27, 2020 at 6:40 AM Taehee Yoo <ap420073@...il.com> wrote:
> > But I'm so sorry I didn't understand some points.
> >
> > 1. you said "both side" and I understand these as follows:
> > a) failure of allocation because of a high order and it is fixed
> > by 72e09ad107e7
> > b) kernel panic because of 72e09ad107e7
> > Are these two issues right?
>
> Yes, we can't fix one by reverting the fix for the other.
>
> >
> > 2. So, as far as I understand your mention, these timers are
> > good to be changed to the delayed works And these timers are mca_timer,
> > mc_gq_timer, mc_ifc_timer, mc_dad_timer.
> > Do I understand your mention correctly?
> > If so, what is the benefit of it?
> > I, unfortunately, couldn't understand the relationship between changing
> > timers to the delayed works and these issues.
>
> Because a work has process context so we can use GFP_KERNEL
> allocation rather than GFP_ATOMIC, which is what commit 72e09ad107e7
> addresses.
>

Thank you for explaining!
I now understand why you suggested it.
I will send a v2 patch which will change timers to delay works.

Thanks a lot!
Taehee Yoo