lkml.org 
[lkml]   [2014]   [Nov]   [27]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [rfc patch] mm: protect set_page_dirty() from ongoing truncation
On Thu, 27 Nov 2014 10:40:06 +0100 Jan Kara <jack@suse.cz> wrote:

> > so we no longer require that the address_space be stabilized after
> > lock_page(). Of course something needs to protect the bdi and I'm not
> > sure what that is, but we're talking about umount and that quiesces and
> > evicts lots of things before proceeding, so surely there's something in
> > there which will save us ;)
> In do_wp_page() the process doing the fault and ending in
> balance_dirty_pages() has to have the page mapped, thus it has to have the
> file open => no umount.

Actually, umount isn't enough to kill the backing_dev_info. It's an
attribute of the device itself (for blockdevs it's a field in
request_queue) so I assume it will be stable until device hot-unplug,
losetup -d, rmmod, etc. If the backing_dev can go away in the middle
of a pagefault against that device then we have bigger problems ;)





\
 
 \ /
  Last update: 2014-11-27 11:21    [W:0.065 / U:2.912 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site