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[173.79.60.52]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-90c5f2b2b38sm67816356d6.43.2026.08.21.10.47.12 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 21 Aug 2026 10:47:12 -0700 (PDT) Date: Fri, 21 Aug 2026 13:47:10 -0400 From: Gregory Price To: Andrew Morton Cc: Eric Dumazet , linux-kernel , syzbot+0dbf6d295b3350944f0b@syzkaller.appspotmail.com, David Hildenbrand , Zi Yan , Matthew Brost , Joshua Hahn , Rakie Kim , Byungchul Park , Ying Huang , Alistair Popple , linux-mm@kvack.org Subject: Re: [PATCH] mm/mempolicy: Fix sleeping allocation in alloc_pages_bulk_weighted_interleave() Message-ID: References: <20260821170407.3721004-1-edumazet@google.com> <20260821104043.f692421fec915c0c5bc1fbe6@linux-foundation.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260821104043.f692421fec915c0c5bc1fbe6@linux-foundation.org> On Fri, Aug 21, 2026 at 10:40:43AM -0700, Andrew Morton wrote: > On Fri, 21 Aug 2026 17:04:07 +0000 Eric Dumazet 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