Couple of questions on OOM trace.

[Jonathan Neuschäfer]

On Wed, May 08, 2013 at 11:27:40PM +0530, Shraddha Kamat wrote:
> 
> Here is the OOM trace header : 
> 
> Out of memory: Kill process 5374 (min_free_kbytes) score 944 or sacrifice child
> Killed process 5374 (min_free_kbytes)  total-vm:30495360kB,anon-rss:20155328kB, file-rss:64kB
> min_free_kbytes invoked oom-killer: gfp_mask=0x200da, order=0, oom_score_adj=0
> min_free_kbytes cpuset=/ mems_allowed=0
> 
> ------------------
> 
> 
> I understand that in this case free pages has gone below min_pages(1). 
> 
> Couple of questions based on these 4 lines : 
> 
> (1) I googled a lot but I am not able to find the meaning of 'score
> 994' , anon-rss and file-rss ? 

Try reading mm/oom_kill.c.

> (2) In my understanding gfp_mask is relevant here to know from which
> Zone the memory allocation was tried , but failed - right ?  
> 
> (3) What do order and oom_score_adj signify here ?

oom_score_adj is a per-process /proc entry to adjust the likelihood that
a particular process is killed by the OOM code.

The word "order" is explained by mm/oom_kill.c, line 600:
 * @order: amount of memory being requested as a power of 2

Or, better yet, mm/mempolicy.c, line 2024:
 * @order: Power of two of allocation size in pages. 0 is a single page.


HTH,
Jonathan Neuschäfer