Re: kstrdup_quotable_cmdline and gfp flags

[Michal Hocko]

On Mon 05-11-18 22:32:07, Rasmus Villemoes wrote:
> kstrdup_quotable_cmdline takes gfp flags and passes those on to
> kstrdup_quotable, but before that it has done a kmalloc(PAGE_SIZE) with
> a hard-coded GFP_KERNEL. There is one caller of kstrdup_quotable_cmdline
> which passes GFP_ATOMIC, and the commit introducing that (65a3c2748e)
> conveniently has this piece of history:
> 
>     v2: Use GFP_ATOMIC while holding the rcu lock per Chris Wilson
> 
> So, should the GFP_KERNEL in kstrdup_quotable_cmdline simply be changed
> to use the passed-in gfp, or is there some deeper reason for the
> GFP_KERNEL (in which case it doesn't really make sense to take gfp at
> all...)?

I would just drop the gfp argument and move comm = kstrdup(task->comm, GFP_ATOMIC);
before rcu read lock

The code in its current form is buggy.
-- 
Michal Hocko
SUSE Labs