Re: [PATCH 1/2] fs: ext4: use BUG_ON if writepage call comes from direct reclaim

[Theodore Y. Ts'o]

On Tue, Jul 03, 2018 at 12:11:18PM +0800, Yang Shi wrote:
> direct reclaim doesn't write out filesystem page, only kswapd could do
> it. So, if the call comes from direct reclaim, it is definitely a bug.
> 
> And, Mel Gormane also mentioned "Ultimately, this will be a BUG_ON." In
> commit 94054fa3fca1fd78db02cb3d68d5627120f0a1d4 ("xfs: warn if direct
> reclaim tries to writeback pages").
> 
> Although it is for xfs, ext4 has the similar behavior, so elevate
> WARN_ON to BUG_ON.
> 
> And, correct the comment accordingly.
> 
> Cc: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
> Cc: "Theodore Ts'o" <tytso@xxxxxxx>
> Cc: Andreas Dilger <adilger.kernel@xxxxxxxxx>
> Signed-off-by: Yang Shi <yang.shi@xxxxxxxxxxxxxxxxx>

What's the upside of crashing the kernel if the file sytsem can handle it?

       	   	     	      	  	    - Ted