Re: OOM panics with zram

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From: Dave Hansen
Date: Sunday, October 3, 2010 - 12:27 pm

On Sun, 2010-10-03 at 14:41 -0400, Nitin Gupta wrote:

I'd argue that zram is pretty useless without some ability to write to a
backing store, unless you *really* know what is going to be stored in it
and you trust the user.  Otherwise, it's just too easy to OOM the
system.

I've been investigating backing the xvmalloc space with a tmpfs file.
Instead of keeping page/offset pairs, you just keep a linear address
inside the tmpfile file.  There's an extra step needed to look up and
lock the page cache page into place each time you go into the xvmalloc
store, but it does seem to basically work.  The patches are really rough
and not quite functional, but I'm happy to share if you want to see them
now.


That looks like just a clone of the code needed to build the module.  

Kernel developers are pretty used to _some_ kernel tree being the
authoritative source.  Also, having it in a kernel tree makes it
possible to get testing in places like linux-next, and it makes it
easier for people to make patches or kernel trees on top of your work. 

There's not really a point to the code being in -staging if it isn't
somewhat up-to-date or people can't generate patches to it.  It sounds
to me like we need to take it out of -staging.

-- Dave

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Messages in current thread:
[PATCH 00/10] zram: various improvements and cleanups, Nitin Gupta, (Mon Aug 9, 10:26 am)
[PATCH 01/10] Replace ioctls with sysfs interface, Nitin Gupta, (Mon Aug 9, 10:26 am)
[PATCH 03/10] Use percpu stats, Nitin Gupta, (Mon Aug 9, 10:26 am)
[PATCH 04/10] Use percpu buffers, Nitin Gupta, (Mon Aug 9, 10:26 am)
[PATCH 06/10] Block discard support, Nitin Gupta, (Mon Aug 9, 10:26 am)
[PATCH 07/10] Increase compressed page size threshold, Nitin Gupta, (Mon Aug 9, 10:26 am)
[PATCH 08/10] Some cleanups, Nitin Gupta, (Mon Aug 9, 10:26 am)
[PATCH 09/10] Update zram documentation, Nitin Gupta, (Mon Aug 9, 10:26 am)
[PATCH 10/10] Document sysfs entries, Nitin Gupta, (Mon Aug 9, 10:26 am)
Re: [PATCH 01/10] Replace ioctls with sysfs interface, Pekka Enberg, (Mon Aug 9, 11:34 am)
Re: [PATCH 03/10] Use percpu stats, Pekka Enberg, (Mon Aug 9, 11:44 am)
Re: [PATCH 04/10] Use percpu buffers, Pekka Enberg, (Mon Aug 9, 11:57 am)
Re: [PATCH 08/10] Some cleanups, Pekka Enberg, (Mon Aug 9, 12:02 pm)
Re: [PATCH 10/10] Document sysfs entries, Pekka Enberg, (Mon Aug 9, 12:02 pm)
Re: [PATCH 06/10] Block discard support, Pekka Enberg, (Mon Aug 9, 12:03 pm)
Re: [PATCH 06/10] Block discard support, Jens Axboe, (Mon Aug 9, 7:23 pm)
Re: [PATCH 03/10] Use percpu stats, Andrew Morton, (Mon Aug 9, 9:34 pm)
Re: [PATCH 04/10] Use percpu buffers, Nitin Gupta, (Mon Aug 9, 9:47 pm)
Re: [PATCH 06/10] Block discard support, Nitin Gupta, (Mon Aug 9, 9:54 pm)
Re: [PATCH 04/10] Use percpu buffers, Pekka Enberg, (Mon Aug 9, 10:05 pm)
Re: [PATCH 04/10] Use percpu buffers, Nitin Gupta, (Mon Aug 9, 10:32 pm)
Re: [PATCH 04/10] Use percpu buffers, Pekka Enberg, (Tue Aug 10, 12:36 am)
Re: [PATCH 06/10] Block discard support, Jens Axboe, (Tue Aug 10, 8:54 am)
Re: [PATCH 03/10] Use percpu stats, Nitin Gupta, (Wed Aug 11, 9:39 am)
Re: [PATCH 03/10] Use percpu stats, Andrew Morton, (Wed Aug 11, 10:18 am)
Re: [PATCH 03/10] Use percpu stats, Christoph Lameter, (Mon Aug 30, 9:20 am)
Re: [PATCH 03/10] Use percpu stats, Nitin Gupta, (Tue Aug 31, 1:31 pm)
Re: [PATCH 03/10] Use percpu stats, Eric Dumazet, (Tue Aug 31, 2:28 pm)
Re: [PATCH 03/10] Use percpu stats, Christoph Lameter, (Tue Aug 31, 2:35 pm)
Re: [PATCH 03/10] Use percpu stats, Eric Dumazet, (Tue Aug 31, 2:41 pm)
Re: [PATCH 01/10] Replace ioctls with sysfs interface, Dave Hansen, (Tue Aug 31, 4:06 pm)
Re: [PATCH 00/10] zram: various improvements and cleanups, Anton Blanchard, (Tue Aug 31, 8:32 pm)
Re: [PATCH 03/10] Use percpu stats, Anton Blanchard, (Tue Aug 31, 8:41 pm)
Re: [PATCH 03/10] Use percpu stats, Anton Blanchard, (Tue Aug 31, 8:51 pm)
Re: [PATCH 03/10] Use percpu stats, Christoph Lameter, (Wed Sep 1, 1:05 pm)
Re: [PATCH 03/10] Use percpu stats, Eric Dumazet, (Wed Sep 1, 1:38 pm)
Re: [PATCH 03/10] Use percpu stats, Christoph Lameter, (Wed Sep 1, 5:34 pm)
Re: [PATCH 03/10] Use percpu stats, Andrew Morton, (Fri Sep 17, 1:59 pm)
Re: OOM panics with zram, Nitin Gupta, (Sun Oct 3, 11:41 am)
Re: OOM panics with zram, Dave Hansen, (Sun Oct 3, 12:27 pm)
Re: OOM panics with zram, Nitin Gupta, (Sun Oct 3, 12:40 pm)
Re: OOM panics with zram, Ed Tomlinson, (Mon Oct 4, 4:08 am)
Re: OOM panics with zram, Greg KH, (Tue Oct 5, 4:43 pm)
Re: OOM panics with zram, Nitin Gupta, (Tue Oct 5, 7:29 pm)
Re: OOM panics with zram, Greg KH, (Tue Oct 5, 7:36 pm)
Re: OOM panics with zram, Nitin Gupta, (Tue Oct 5, 9:30 pm)
Re: OOM panics with zram, Pekka Enberg, (Wed Oct 6, 12:38 am)
Re: OOM panics with zram, Greg KH, (Wed Oct 6, 7:02 am)
Re: OOM panics with zram, Greg KH, (Wed Oct 6, 7:03 am)
Re: OOM panics with zram, Pekka Enberg, (Wed Oct 6, 7:16 am)
Re: OOM panics with zram, Nitin Gupta, (Wed Oct 6, 7:53 am)