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

[Glauber Costa]

On 04/11/2012 03:57 PM, Linus Torvalds wrote:
> On Wed, Apr 11, 2012 at 11:48 AM, Michal Hocko<mhocko at suse.cz>  wrote:
>>
>> I am not familiar with the code much but a trivial call chain walk up to
>> write_dev_supers (in btrfs) shows that we do not check for the return value
>> from __getblk so we would nullptr and there might be more.
>> I guess these need some treat before the BUG might be removed, right?
>
> Well, realistically, isn't BUG() as bad as a NULL pointer dereference?
>
> Do you care about the exact message on the screen when your machine dies?
Not particular, but I don't see why (I might be wrong) it would 
necessarily lead to a NULL pointer dereference.

At least in my test cases, after turning this to a WARN (to make sure it 
was still being hit), the machine could go on just fine.

I was running this in a container system, with restricted memory. After
killing the container - at least in my ext4 system - everything seemed 
as happy as ever.