Re: [PATCH] remove BUG() in possible but rare condition

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On 04/11/2012 05:26 PM, Andrew Morton wrote:

>    failed:
>  -	BUG();
>    	unlock_page(page);
>    	page_cache_release(page);
>    	return NULL;
Cute.

AFAICT what happened was that in my April 2002 rewrite of this code I
put a non-fatal buffer_error() warning in that case to tell us that
something bad happened.

Years later we removed the temporary buffer_error() and mistakenly
replaced that warning with a BUG().  Only it*can*  happen.

We can remove the BUG() and fix up callers, or we can pass retry=1 into
alloc_page_buffers(), so grow_dev_page() "cannot fail".  Immortal
functions are a silly fiction, so we should remove the BUG() and fix up
callers.

Any particular caller you are concerned with ?

As I mentioned, this function already returns NULL for other reason - that seem even more probable than this specific failure. So whoever is not checking this return value, is already broken without this patch as well.


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