Re: [PATCH 1/2] mm: add GFP mask param to strndup_user

[Alexey Dobriyan]

On Sat, Aug 15, 2020 at 11:42:10PM +0100, Al Viro wrote:
> On Sat, Aug 15, 2020 at 11:23:43AM -0700, Pascal Bouchareine wrote:
> > Let caller specify allocation.
> > Preserve existing calls with GFP_USER.
> 
> Bloody bad idea, unless you slap a BUG_ON(flags & GFP_ATOMIC) on it,
> to make sure nobody tries _that_.  Note that copying from userland
> is an inherently blocking operation, and this interface invites
> just that.
> 
> What do you need that flag for, anyway?

You need it for kmem accounting.