linux-kernel - Re: [PATCH 2/5] proc: use down_read_killable for /proc/pid/smaps

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Message-ID: <20190610185804.GB2388@dhcp22.suse.cz>
Date:   Mon, 10 Jun 2019 20:58:04 +0200
From:   Michal Hocko <mhocko@...nel.org>
To:     Konstantin Khlebnikov <khlebnikov@...dex-team.ru>
Cc:     linux-mm@...ck.org, Andrew Morton <akpm@...ux-foundation.org>,
        linux-kernel@...r.kernel.org, Cyrill Gorcunov <gorcunov@...il.com>,
        Kirill Tkhai <ktkhai@...tuozzo.com>,
        Al Viro <viro@...iv.linux.org.uk>
Subject: Re: [PATCH 2/5] proc: use down_read_killable for
 /proc/pid/smaps_rollup

On Sun 09-06-19 12:07:36, Konstantin Khlebnikov wrote:
[...]
> > > diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
> > > index 2bf210229daf..781879a91e3b 100644
> > > --- a/fs/proc/task_mmu.c
> > > +++ b/fs/proc/task_mmu.c
> > > @@ -832,7 +832,10 @@ static int show_smaps_rollup(struct seq_file *m, void *v)
> > >   	memset(&mss, 0, sizeof(mss));
> > > -	down_read(&mm->mmap_sem);
> > > +	ret = down_read_killable(&mm->mmap_sem);
> > > +	if (ret)
> > > +		goto out_put_mm;
> > 
> > Why not ret = -EINTR. The seq_file code seems to be handling all errors
> > AFAICS.
> > 
> 
> I've missed your comment. Sorry.
> 
> down_read_killable returns 0 for success and exactly -EINTR for failure.

You are right of course. I must have misread the code at the time. Sorry
about that.
-- 
Michal Hocko
SUSE Labs