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Mon, 16 Jun 2025 19:02:04 +0800 From: "Huang, Ying" To: David Hildenbrand Cc: Bijan Tabatabai , linux-mm@kvack.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, sj@kernel.org, akpm@linux-foundation.org, corbet@lwn.net, ziy@nvidia.com, matthew.brost@intel.com, joshua.hahnjy@gmail.com, rakie.kim@sk.com, byungchul@sk.com, gourry@gourry.net, apopple@nvidia.com, bijantabatab@micron.com, venkataravis@micron.com, emirakhur@micron.com, ajayjoshi@micron.com, vtavarespetr@micron.com, damon@lists.linux.dev Subject: Re: [RFC PATCH 1/4] mm/mempolicy: Expose policy_nodemask() in include/linux/mempolicy.h In-Reply-To: (David Hildenbrand's message of "Mon, 16 Jun 2025 11:45:58 +0200") References: <20250612181330.31236-1-bijan311@gmail.com> <20250612181330.31236-2-bijan311@gmail.com> <5a50eeba-b26d-4913-8016-45278608a1ee@redhat.com> Date: Mon, 16 Jun 2025 19:02:03 +0800 Message-ID: <87plf43q6s.fsf@DESKTOP-5N7EMDA> User-Agent: Gnus/5.13 (Gnus v5.13) MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-Rspam-User: X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 8C195100018 X-Stat-Signature: q8e3ztjfeufft1efpka1uy5zzr7t3ikd X-HE-Tag: 1750071729-800631 X-HE-Meta: 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 OrCh69Kj ayvKpecW7NkSv/0aClyIDDdbbCswev2C9mJj9Gv90h3LKnuSDQu3fih99ABs2RCzCWxefe6ht37gWi3IpH6j8aCttLYlRnpNVIfxFVYUncGp+L/REFnqGL3JdWxUSHFff4dAWKrQoqxOppGR3qO2dxdygjAEKjTNHvSAkJVo+TWGyYooWqbc8zBIFFTb+/h0r02rl4NSqyRFJgdgv+RdZ/9Dx+cybqaQlfBwLXKy+wHP3m2UDnKa/1nijbx8jl9swCkj9mk59FHq5YvKJ/aZsCeojlp/HAL1gumAcrs9+Z86hVmo2TC3auE9XxuFwZxmdGlK3PQ3iiFB/5bWJDFDHH7zcPcFejrgsE3qyzCXOeMaKNAsFq23Sa1gmFITPG1UOBYDhNGmAecg+wmH1jzY/srNKecmJOSX2o1xT18QooSEY9nhfqbIc1MCKsHSrrWviG95KpIB6Nl7FmrcXli+maThmmmZAo7snlTUTYK+eT7R7QIA= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: David Hildenbrand writes: > On 13.06.25 18:33, Bijan Tabatabai wrote: >> On Fri, Jun 13, 2025 at 8:45=E2=80=AFAM David Hildenbrand wrote: >>> >>> On 12.06.25 20:13, Bijan Tabatabai wrote: >>>> From: Bijan Tabatabai >>>> [snip] >> I did not use get_vma_policy or mpol_misplaced, which I believe is >> the >> closest function that exists for what I want in this patch, because >> those functions > > I think what you mean is, that you are performing an rmap walk. But > there, you do have a VMA + MM available (stable). > >> seem to assume they are called inside of the task that the folio/vma >> is mapped to. > > But, we do have a VMA at hand, so why would we want to ignore any set > policy? (I think VMA policies so far only apply to shmem, but still). > > I really think you want to use get_vma_policy() instead of the task polic= y. > > >> More specifically, mpol_misplaced assumes it is being called within a >> page fault. >> This doesn't work for us, because we call it inside of a kdamond process. > > Right. > > But it uses the vmf only for ... > > 1) Obtaining the VMA > 2) Sanity-checking that the ptlock is held. 3) update NUMA balancing per-folio cpupid state (via should_numa_migrate_me= mory()). This needs to be called by the NUMA page fault handler. > Which, you also have during the rmap walk. > [snip] --- Best Regards, Huang, Ying