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Date:   Thu, 13 Jun 2019 09:48:16 +0300
From:   Cyrill Gorcunov <gorcunov@gmail.com>
To:     Andrei Vagin <avagin@gmail.com>
Cc:     Konstantin Khlebnikov <khlebnikov@yandex-team.ru>,
        linux-mm@kvack.org, Andrew Morton <akpm@linux-foundation.org>,
        linux-kernel@vger.kernel.org, Oleg Nesterov <oleg@redhat.com>,
        Matthew Wilcox <willy@infradead.org>,
        Michal Hocko <mhocko@kernel.org>,
        Kirill Tkhai <ktkhai@virtuozzo.com>,
        Michal =?iso-8859-1?Q?Koutn=FD?= <mkoutny@suse.com>,
        Al Viro <viro@zeniv.linux.org.uk>,
        Roman Gushchin <guro@fb.com>, Dmitry Safonov <dima@arista.com>
Subject: Re: [PATCH v2 5/6] proc: use down_read_killable mmap_sem for
 /proc/pid/map_files
Message-ID: <20190613064816.GF23535@uranus.lan>
References: <156007465229.3335.10259979070641486905.stgit@buzz>
 <156007493995.3335.9595044802115356911.stgit@buzz>
 <20190612231426.GA3639@gmail.com>
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On Wed, Jun 12, 2019 at 04:14:28PM -0700, Andrei Vagin wrote:
> On Sun, Jun 09, 2019 at 01:09:00PM +0300, Konstantin Khlebnikov wrote:
> > Do not stuck forever if something wrong.
> > Killable lock allows to cleanup stuck tasks and simplifies investigation.
> 
> This patch breaks the CRIU project, because stat() returns EINTR instead
> of ENOENT:
> 
> [root@fc24 criu]# stat /proc/self/map_files/0-0
> stat: cannot stat '/proc/self/map_files/0-0': Interrupted system call
> 
> Here is one inline comment with the fix for this issue.
> 
> > 
> > It seems ->d_revalidate() could return any error (except ECHILD) to
> > abort validation and pass error as result of lookup sequence.
> > 
> > Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
> > Reviewed-by: Roman Gushchin <guro@fb.com>
> > Reviewed-by: Cyrill Gorcunov <gorcunov@gmail.com>
> > Reviewed-by: Kirill Tkhai <ktkhai@virtuozzo.com>
> 
> It was nice to see all four of you in one place :).

Holymoly ;) And we all managed to miss this error code.
Thanks, Andrew!