linux-kernel - Re: [PATCH] mm: hwpoison: use do_send_sig_info() instead of force_sig() (Re: PMEM error-handling forces SIGKILL causes kernel panic)

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Date:   Wed, 16 Jan 2019 23:32:07 +0000
From:   Naoya Horiguchi <n-horiguchi@...jp.nec.com>
To:     Jane Chu <jane.chu@...cle.com>
CC:     Dan Williams <dan.j.williams@...el.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        linux-nvdimm <linux-nvdimm@...ts.01.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] mm: hwpoison: use do_send_sig_info() instead of
 force_sig() (Re: PMEM error-handling forces SIGKILL causes kernel panic)

Hi Jane,

On Wed, Jan 16, 2019 at 09:56:02AM -0800, Jane Chu wrote:
> Hi, Naoya,
> 
> On 1/16/2019 1:30 AM, Naoya Horiguchi wrote:
> 
>     diff --git a/mm/memory-failure.c b/mm/memory-failure.c
>     index 7c72f2a95785..831be5ff5f4d 100644
>     --- a/mm/memory-failure.c
>     +++ b/mm/memory-failure.c
>     @@ -372,7 +372,8 @@ static void kill_procs(struct list_head *to_kill, int forcekill, bool fail,
>                             if (fail || tk->addr_valid == 0) {
>                                     pr_err("Memory failure: %#lx: forcibly killing %s:%d because of failure to unmap corrupted page\n",
>                                            pfn, tk->tsk->comm, tk->tsk->pid);
>     -                               force_sig(SIGKILL, tk->tsk);
>     +                               do_send_sig_info(SIGKILL, SEND_SIG_PRIV,
>     +                                                tk->tsk, PIDTYPE_PID);
>                             }
> 
> 
> Since we don't care the return from do_send_sig_info(), would you mind to
> prefix it with (void) ?

Sorry, I'm not sure about the benefit to do casting the return value
just being ignored, so personally I'd like keeping the code simple.
Do you have some in mind?

- Naoya