On Thu, Mar 17, 2016 at 1:57 PM, Chris Wilson <[email protected]> wrote: > On Thu, Mar 17, 2016 at 01:37:06PM +0100, Roman Peniaev wrote: >> > + freed = 0; >> > + blocking_notifier_call_chain(&vmap_notify_list, 0, &freed); >> >> It seems to me that alloc_vmap_area() was designed not to sleep, >> at least on GFP_NOWAIT path (__GFP_DIRECT_RECLAIM is not set). >> >> But blocking_notifier_call_chain() might sleep. > > Indeed, I had not anticipated anybody using GFP_ATOMIC or equivalently > restrictive gfp_t for vmap and yes there are such callers. > > Would guarding the notifier with gfp & __GFP_DIRECT_RECLAIM and > !(gfp & __GFP_NORETRY) == be sufficient? Is that enough for GFP_NOFS?
I would use gfpflags_allow_blocking() for that purpose. Roman
