Re: [PATCH] mm/mempolicy: Fix sleeping allocation in alloc_pages_bulk_weighted_interleave()

[Gregory Price]

On Fri, Aug 21, 2026 at 10:40:43AM -0700, Andrew Morton wrote:
> On Fri, 21 Aug 2026 17:04:07 +0000 Eric Dumazet <edumazet@xxxxxxxxxx> wrote:
> 
> I wonder if we *really* need the local copy of state->iw_table. 
> Perhaps with appropriate care we can directly use state->iw_table in
> here.
> 
> How much would it hurt to expand the rcu_read_lock() coverage?
> 
> A local array of MAX_NUMNODES bytes isn't attractive - 1k of stack.
> 
> A spinlock-protected static array would work, if super-rare slowpath.
> 

I would need to go back through the original thread when i authored
this, but I think this is possible.  I will add it to my backlog to
investigate.

Weight updates should be *extraordinarily* rare, unless someone is doing
dynamic runtime twiddling of the sysfs values and thinks that's somehow
a good idea (or expecting them to be timely).

~Gregory