Thread (7 messages) 7 messages, 3 authors, 2016-08-04

Re: every boot gives: bcache/alloc.c:78 WARNING

From: Eric Wheeler <hidden>
Date: 2016-08-04 02:53:19

On Wed, 3 Aug 2016, Eric Wheeler wrote:
On Wed, 3 Aug 2016, Marc MERLIN wrote:
quoted
On Wed, Aug 03, 2016 at 05:26:30PM -0700, Eric Wheeler wrote:
quoted
On Wed, 3 Aug 2016, Marc MERLIN wrote:
quoted
This happens on all kernels up to 4.7.
Sorry, it happens earlier than ethernet coming up or my storage, so I can't
use netconsole or other text dumps:
https://goo.gl/photos/ubsi6maZXsjkevYY7

Looks like the warning happens on the registration of one of my bcache, but
I can't tell which one or why.

Does the trace give any hints?
(please ignore the load modules errors below, different issue)
Does it cause a problem, or just warn?
 
No problem, but since it's a warning, I'm reporting it.
quoted
It looks like something needs garbage collected but perhaps isn't.  

You could write to sysfs/.../trigger_gc:
 
https://evilpiepirate.org/git/linux-bcache.git/tree/Documentation/bcache.txt
	trigger_gc
	  Writing to this file forces garbage collection to run.
BTW both this and the just released 4.7.0 are still missing the
documentation updates I contributed months ago. Any idea what's going on
there?
quoted
If that doesn't work, I wonder what increasing BUCKET_GC_GEN_MAX would do, 
though I don't know if that is safe.  Its set to 96U, so its not on on a 
bit boundary which sounds like it could be slightly safer---but I wouldn't 
try it unless this is a test machine.
That's on the backing device, correct?
I have 3 of them, and I can only write to them way way later in the boot
process.
Should I do that one by one and see if I get output now?

When you say do "that" do you mean `trigger_gc` ?

I think trigger_gc a cache thing, but the whole bcacheN dev might need to 
be online before it can be triggered (not sure).  Backing devices really 
have metadata, just superblock.
I meant to say: 

Backing devices have no metadata, just superblock.



--
Eric Wheeler

--
Eric Wheeler

quoted
Thanks,
Marc
-- 
"A mouse is a device used to point at the xterm you want to type in" - A.S.R.
Microsoft is to operating systems ....
                                      .... what McDonalds is to gourmet cooking
Home page: http://marc.merlins.org/  
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