Re: [RFC] Per file OOM badness

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On 30.01.2018 11:48, Michel Dänzer wrote:
On 2018-01-30 11:42 AM, Daniel Vetter wrote:
On Tue, Jan 30, 2018 at 10:43:10AM +0100, Michel Dänzer wrote:
On 2018-01-30 10:31 AM, Daniel Vetter wrote:

I guess a good first order approximation would be if we simply charge any
newly allocated buffers to the process that created them, but that means
hanging onto lots of mm_struct pointers since we want to make sure we then
release those pages to the right mm again (since the process that drops
the last ref might be a totally different one, depending upon how the
buffers or DRM fd have been shared).

Would it be ok to hang onto potentially arbitrary mmget references
essentially forever? If that's ok I think we can do your process based
account (minus a few minor inaccuracies for shared stuff perhaps, but no
one cares about that).

Honestly, I think you and Christian are overthinking this. Let's try
charging the memory to every process which shares a buffer, and go from
there.

I'm not concerned about wrongly accounting shared buffers (they don't
matter), but imbalanced accounting. I.e. allocate a buffer in the client,
share it, but then the compositor drops the last reference.

I don't think the order matters. The memory is "uncharged" in each
process when it drops its reference.

Daniel made a fair point about passing DRM fds between processes, though.

It's not a problem with how the fds are currently used, but somebody could do the following:

1. Create a DRM fd in process A, allocate lots of buffers.
2. Pass the fd to process B via some IPC mechanism.
3. Exit process A.

There needs to be some assurance that the BOs are accounted as belonging to process B in the end.

Cheers,
Nicolai
--
Lerne, wie die Welt wirklich ist,
Aber vergiss niemals, wie sie sein sollte.

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@xxxxxxxxx.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>



[Index of Archives]     [Linux ARM Kernel]     [Linux ARM]     [Linux Omap]     [Fedora ARM]     [IETF Annouce]     [Bugtraq]     [Linux OMAP]     [Linux MIPS]     [eCos]     [Asterisk Internet PBX]     [Linux API]
  Powered by Linux