Re: [PATCH v2 5/6] proc: use down_read_killable mmap_sem for /proc/pid/map_files

[Cyrill Gorcunov]

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@xxxxxxxxxxxxxx>
> > Reviewed-by: Roman Gushchin <guro@xxxxxx>
> > Reviewed-by: Cyrill Gorcunov <gorcunov@xxxxxxxxx>
> > Reviewed-by: Kirill Tkhai <ktkhai@xxxxxxxxxxxxx>
> 
> It was nice to see all four of you in one place :).

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