On Thu, Mar 17, 2016 at 02:21:40PM +0100, Roman Peniaev wrote:

On Thu, Mar 17, 2016 at 1:57 PM, Chris Wilson [off-list ref] wrote:

quoted

On Thu, Mar 17, 2016 at 01:37:06PM +0100, Roman Peniaev wrote:

quoted

quoted

+       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.

Thanks,
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre

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