linux-kernel - Re: [RFC PATCH 0/4] Add fbind() and NUMA mempolicy support for KVM guest

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Message-ID: <ZypqJ0e-J3C_K8LA@casper.infradead.org>
Date: Tue, 5 Nov 2024 18:55:35 +0000
From: Matthew Wilcox <willy@...radead.org>
To: Shivank Garg <shivankg@....com>
Cc: x86@...nel.org, viro@...iv.linux.org.uk, brauner@...nel.org,
	jack@...e.cz, akpm@...ux-foundation.org,
	linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
	linux-mm@...ck.org, linux-api@...r.kernel.org,
	linux-arch@...r.kernel.org, kvm@...r.kernel.org, chao.gao@...el.com,
	pgonda@...gle.com, thomas.lendacky@....com, seanjc@...gle.com,
	luto@...nel.org, tglx@...utronix.de, mingo@...hat.com, bp@...en8.de,
	dave.hansen@...ux.intel.com, arnd@...db.de, pbonzini@...hat.com,
	kees@...nel.org, bharata@....com, nikunj@....com,
	michael.day@....com, Neeraj.Upadhyay@....com
Subject: Re: [RFC PATCH 0/4] Add fbind() and NUMA mempolicy support for KVM
 guest_memfd

On Tue, Nov 05, 2024 at 04:45:45PM +0000, Shivank Garg wrote:
> This patch series introduces fbind() syscall to support NUMA memory
> policies for KVM guest_memfd, allowing VMMs to configure memory placement
> for guest memory. This addresses the current limitation where guest_memfd
> allocations ignore NUMA policies, potentially impacting performance of
> memory-locality-sensitive workloads.

Why does guest_memfd ignore numa policies?  The pagecache doesn't,
eg in vma_alloc_folio_noprof().