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a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1792393129; bh=jKcRI0F9aHnlKD651grREaBBW4xvRcUMzBlgAiHKlsU=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=StlLDKq4P1yblYmcNUL/S2ln1AqLeYYRPcJPR+/GUUMAOs1w3CfSJYbdyEfSHULs+ yNXPO49brP9+UjPFeg1bY6f39wNxEV9GIf+ejuiDxy5qXrhRH/cH9ROgchLpwdaLtX AYklqgynUtNpXJDDuA7feuEpCmp7LhrGsihDk9Ms= Message-ID: <4aa14b41-9b89-494c-8825-55fffd5a541c@arm.com> Date: Mon, 19 Oct 2026 12:28:40 +0530 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3] mm: page_alloc: make defrag_mode retries follow the promoted order To: Kiryl Shutsemau , "Vlastimil Babka (SUSE)" Cc: Johannes Weiner , Andrew Morton , David Hildenbrand , Harry Yoo , Usama Arif , Suren Baghdasaryan , Michal Hocko , Brendan Jackman , Zi Yan , Shakeel Butt , linux-mm@kvack.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@meta.com References: <20261009125503.126202-1-kas@kernel.org> <15a9e03e-c748-4e51-b8cc-583a3610c897@kernel.org> <20261012192834.6934ef85444dee4a60d6d876@linux-foundation.org> <20261014202936.GC371161@cmpxchg.org> <78238103-3a7f-432c-b1df-bd14d7cf4bb1@kernel.org> Content-Language: en-US From: Dev Jain In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 876192000A X-Rspam-User: X-Stat-Signature: mpdihd4dg4eqmb7qyo3eqt7w4sd8pzsk X-HE-Tag: 1792393130-943905 X-HE-Meta: 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 hUSfauvS 2/MNLZgRrQjxXWBDo6E5VUGoYLeeCHIdOCamluaGQ670W3L6YjVh39Re1GnONcOb3u8SLZC7MqlbmxDkD/pAcFYGvQMkeY4MPL8hrFQ/XOG9NFNzZUNMSsw4nI6iphFguc/GW99zOEJnWugm/e/Pn+SknMIvOeBBZa+81xL+TrrL6z15UMIoZdaXEFA1YPvkxFi1YZ5iqf5wkmi88LtJu03jClsaklytnhb3WTz9KwXz1dbxo+3jZfNXHheX7DENysYTr4Lt5jGbnE7W1I4f3Nl0ojGr+OzZuHnG6 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 15/10/26 6:25 pm, Kiryl Shutsemau wrote: > On Thu, Oct 15, 2026 at 09:16:36AM +0200, Vlastimil Babka (SUSE) wrote: >>> And agree 7.4-rc1 with CC stable is fine. Sadly, not sure if anyone >>> but Meta is using the feature right now. >> >> I thought it was there for a long time but it was only added in 2025 :) At >> least the enterprise world is slow to adopt things, AFAICS. > > I was thinking to propose a patch after merge window to make defrag_mode > default. Do you think it is too early? I don't think it is ever going > to be truly stabilized without wider exposure. AFAIU defrag mode is not going to improve mTHP allocation success. I ran a synthetic benchmark faulting in lots of 64k mTHP with swap enabled, defrag mode caused me to enter a warn_alloc (and 8 times more compact_stalls), which didn't happen without defrag. So perhaps bundle the default with pageblock_order eagerness etc. > > We also discussed with Johannes to make a stricter (defrag_mode=2?) mode > that will not give up on fragmentation ever, but OOM instead. >