Re: [Bug #12210] 2.6.28-rc8 big regression in VM

From: Wu Fengguang
Date: Mon Mar 02 2009 - 21:17:54 EST


Hi Lukas,

On Thu, Feb 26, 2009 at 08:06:36PM +0200, Lukas Hejtmanek wrote:
> Hello,
>
> you may remember that I reported regression in VM. I used you filecache module
> and discovered that the leaks are caused by these items:
> # filecache 1.0
> # ino size cached cached% refcnt state dev file
> 167302 16 16 100 1 d- 00:08(tmpfs) /drm\040mm\040object\040(deleted)
> 167301 16 16 100 1 d- 00:08(tmpfs) /drm\040mm\040object\040(deleted)
> 167300 16 16 100 1 d- 00:08(tmpfs) /drm\040mm\040object\040(deleted)
> 167299 4 4 100 1 -- 00:08(tmpfs) /drm\040mm\040object\040(deleted)
> 167290 8 8 100 1 -- 00:08(tmpfs) /drm\040mm\040object\040(deleted)
> 167289 8 8 100 1 -- 00:08(tmpfs) /drm\040mm\040object\040(deleted)
> 167288 16 16 100 1 -- 00:08(tmpfs) /drm\040mm\040object\040(deleted)
> 167287 16 16 100 1 d- 00:08(tmpfs) /drm\040mm\040object\040(deleted)
>
> there are tons of those items:
> cat /proc/filecache | grep drm | wc -l
> 14224
>
> Do you have any clues what happens here? Is it a bug in kernel VM system or it
> is more likely a bug in Intel's GEM drm driver? Right now it results in 500MB
> of undropable cache.

Could you provide the full filecache listing(the 'size' field may
provide some info), and the contents in /proc/dri/0/*?

> Also lsof reports many leaked file descriptors:
> lsof | grep drm | wc -l
> 7326

Simply being "deleted" does not mean that they are leaked files.
shmem files are special.

Thanks,
Fengguang

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