From: Andrew Morton <akpm@linux-foundation.org>
To: Peter Xu <peterx@redhat.com>
Cc: syzbot <syzbot+693dc11fcb53120b5559@syzkaller.appspotmail.com>,
bgeffon@google.com, linux-kernel@vger.kernel.org,
linux-mm@kvack.org, syzkaller-bugs@googlegroups.com,
torvalds@linux-foundation.org
Subject: Re: BUG: unable to handle kernel paging request in kernel_get_mempolicy
Date: Mon, 6 Apr 2020 18:39:41 -0700 [thread overview]
Message-ID: <20200406183941.38a2e52026e42dbfde239a56@linux-foundation.org> (raw)
In-Reply-To: <20200407004745.GA48345@xz-x1>
On Mon, 6 Apr 2020 20:47:45 -0400 Peter Xu <peterx@redhat.com> wrote:
> >From 23800bff6fa346a4e9b3806dc0cfeb74498df757 Mon Sep 17 00:00:00 2001
> From: Peter Xu <peterx@redhat.com>
> Date: Mon, 6 Apr 2020 20:40:13 -0400
> Subject: [PATCH] mm/mempolicy: Allow lookup_node() to handle fatal signal
>
> lookup_node() uses gup to pin the page and get node information. It
> checks against ret>=0 assuming the page will be filled in. However
> it's also possible that gup will return zero, for example, when the
> thread is quickly killed with a fatal signal. Teach lookup_node() to
> gracefully return an error -EFAULT if it happens.
>
> ...
>
> --- a/mm/mempolicy.c
> +++ b/mm/mempolicy.c
> @@ -902,7 +902,10 @@ static int lookup_node(struct mm_struct *mm, unsigned long addr)
>
> int locked = 1;
> err = get_user_pages_locked(addr & PAGE_MASK, 1, 0, &p, &locked);
> - if (err >= 0) {
> + if (err == 0) {
> + /* E.g. GUP interupted by fatal signal */
> + err = -EFAULT;
> + } else if (err > 0) {
> err = page_to_nid(p);
> put_page(p);
> }
Doh. Thanks.
Should it have been -EINTR?
next prev parent reply other threads:[~2020-04-07 1:39 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-06 18:16 BUG: unable to handle kernel paging request in kernel_get_mempolicy syzbot
2020-04-07 0:47 ` Peter Xu
2020-04-07 1:05 ` Randy Dunlap
2020-04-07 1:05 ` syzbot
2020-04-07 1:06 ` syzbot
2020-04-07 1:27 ` Peter Xu
2020-04-07 5:26 ` syzbot
2020-04-07 1:39 ` Andrew Morton [this message]
2020-04-07 1:55 ` Peter Xu
2020-04-07 2:15 ` Andrew Morton
2020-04-07 2:42 ` Peter Xu
2020-04-07 8:27 ` Dmitry Vyukov
2020-04-07 15:59 ` Peter Xu
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