linux-kernel - Re: [PATCH 1/2] mm/page_alloc: Ensure try_alloc_pages() plays well with unaccepted memory

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Message-ID: <5loiv7lfplpruujplz7wmzj25g34rs2aezvrfsl55dsddrh7mo@rnqrlx5zccol>
Date: Tue, 6 May 2025 22:00:12 +0300
From: "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
To: Alexei Starovoitov <alexei.starovoitov@...il.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>, 
	Vlastimil Babka <vbabka@...e.cz>, Suren Baghdasaryan <surenb@...gle.com>, 
	Michal Hocko <mhocko@...e.com>, Brendan Jackman <jackmanb@...gle.com>, 
	Johannes Weiner <hannes@...xchg.org>, Borislav Petkov <bp@...en8.de>, 
	Thomas Gleixner <tglx@...utronix.de>, David Hildenbrand <david@...hat.com>, 
	Alexei Starovoitov <ast@...nel.org>, linux-mm <linux-mm@...ck.org>, linux-coco@...ts.linux.dev, 
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/2] mm/page_alloc: Ensure try_alloc_pages() plays well
 with unaccepted memory

On Tue, May 06, 2025 at 10:18:21AM -0700, Alexei Starovoitov wrote:
> On Tue, May 6, 2025 at 4:25 AM Kirill A. Shutemov
> <kirill.shutemov@...ux.intel.com> wrote:
> >
> > try_alloc_pages() will not attempt to allocate memory if the system has
> > *any* unaccepted memory. Memory is accepted as needed and can remain in
> > the system indefinitely, causing the interface to always fail.
> >
> > Rather than immediately giving up, attempt to use already accepted
> > memory on free lists.
> >
> > Pass 'alloc_flags' to cond_accept_memory() and do not accept new memory
> > for ALLOC_TRYLOCK requests.
> >
> > Signed-off-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
> > Fixes: 97769a53f117 ("mm, bpf: Introduce try_alloc_pages() for opportunistic page allocation")
> 
> Thanks for working on this, but the fixes tag is overkill.
> This limitation is not causing any issues in our setups.

Have you had chance to test it on any platform with unaccepted memory?
So far it is only Intel TDX and AMD SEV guests.

> Improving it is certainly better, of course.
> Acked-by: Alexei Starovoitov <ast@...nel.org>

Thanks!

-- 
  Kiryl Shutsemau / Kirill A. Shutemov