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Wed, 21 Oct 2026 05:33:42 -0400 (EDT) Date: Wed, 21 Oct 2026 10:33:41 +0100 From: Kiryl Shutsemau To: Dev Jain Cc: "Vlastimil Babka (SUSE)" , 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 Subject: Re: [PATCH v3] mm: page_alloc: make defrag_mode retries follow the promoted order Message-ID: 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> <4aa14b41-9b89-494c-8825-55fffd5a541c@arm.com> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4aa14b41-9b89-494c-8825-55fffd5a541c@arm.com> On Mon, Oct 19, 2026 at 12:28:40PM +0530, Dev Jain wrote: > > > 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. Could you share the benchmark? I would like to play with it. Which THP defrag setting, and was the range MADV_HUGEPAGE? With the default "madvise" and no MADV_HUGEPAGE, a 64k fault cannot reclaim and does not wake kswapd. How is your system setup? > So perhaps bundle the default with pageblock_order eagerness etc. What do you mean by pageblock_order eagerness? -- Kiryl Shutsemau / Kirill A. Shutemov