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b=lKK7qS3ayOUoGqbDi/TxN4vTUQ3c46MmEmzbBUj7+5tgh6t0FPyeD7sJH8+N+7eN6 n4VRIjKu06gOYUah6DD63yV3pxz98udRx98r2J2kng87LWbCrR47I66j5SxjUDON1z /ifzB/LubUG0VxRxXXb6CxJ9N5VBoNo+xwWi5fjGMTBY6nz+Y/VCnmyHnQITS7R2YW aM72WF9/KZrqnZYjlRNnfJd+gUJmkNOeiZYvX1AAjz7q83GOOCaC2OX/cF28RGnqWS Ux9gp16W04ABGFXsAK6AGep466gRcm7OcBiQxxJ1dgSDMLpQ7LkwTVuWRJBrj2uuz4 +fExMa0KST6MA== From: SJ Park To: zjh Cc: SJ Park , Andrew Morton , damon@lists.linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm/damon: prevent migration fallback to non-target nodes Date: Wed, 8 Jul 2026 07:11:33 -0700 Message-ID: <20260708141134.123360-1-sj@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 60EB380012 X-Stat-Signature: 7wp3itcx3smrakud3hy4ped5ywqyd5cn X-HE-Tag: 1783519899-687712 X-HE-Meta: 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 QiQnBB4d wJO3575Hlj7/rDFYqAQPuRxTrqoMX01D+2NuMY/ABYY7452taYKCPmuXJ/v6XhI8tLg8eeXU3kPvkXWXZ6ojOzvVr9i73fjjNaKfrptYVZrqbW+fcNbF4QRxPFbPLaK8LIaoIxYEaDQMCvWxJaO/GKLl9ep9Zwh3hSxtTVLGcT+hE4d75IeAhOG0HvRx6h0NuCxXUgh+s/dMQlhSncQZpRCbWXgctvj3vGJC7J4/3mtu0p1IjWSuiBuJzCYL95rKawkLhd+ND9MLXETJ4hyDj9SSEhg== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Hello jzh, On Wed, 8 Jul 2026 01:07:54 -0700 zjh wrote: > DAMOS_MIGRATE_{HOT,COLD} passes a target NUMA node to migrate_pages(). > But alloc_migration_target() treats mtc->nid as a preferred node unless > __GFP_THISNODE is set. Hence target allocation can fall back to another > node, and migrate_pages() can report success without placing the folio on > the requested target node. > > Make DAMON migration target allocation strict by setting __GFP_THISNODE. > This is consistent with alloc_misplaced_dst_folio() and > alloc_demote_folio(), which also use __GFP_THISNODE for migrations to an > explicit destination node. Thank you for sharing this patch. So this patch is introducing a small behavioral change. May I ask why you think the new behavior is better? Have you find some negative user impacts from the current behavior? > > Signed-off-by: zjh We as the kernel community disallow [1] anonymous patch submissions. Is zjh your preferred identity? Also, it is not a strict rule, but we as the mm community prefer using a formal name if that's ok. [1] https://docs.kernel.org/process/submitting-patches.html#developer-s-certificate-of-origin-1-1 Thanks, SJ [...]