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Thu, 18 Jun 2026 21:11:19 -0700 (PDT) Received: from pve-server ([49.205.216.49]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-8455382b766sm793864b3a.47.2026.06.18.21.11.12 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 18 Jun 2026 21:11:17 -0700 (PDT) From: Ritesh Harjani (IBM) To: Kairui Song Cc: linux-mm@kvack.org, Madhavan Srinivasan , Michael Ellerman , Nicholas Piggin , Christophe Leroy , Andrew Morton , Chris Li , Kairui Song , Kemeng Shi , Nhat Pham , Baoquan He , Barry Song , Youngjun Park , David Hildenbrand , linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, Sayali Patil Subject: Re: [PATCH v3 1/3] mm, swap: make SWAPFILE_CLUSTER runtime In-Reply-To: Date: Fri, 19 Jun 2026 09:36:17 +0530 Message-ID: <5x3fdvie.ritesh.list@gmail.com> References: <1e8d7e4d0bb1377277ae8b6561d89fa0e048e7de.1781287297.git.ritesh.list@gmail.com> X-Rspam-User: X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 8AEB840004 X-Stat-Signature: aetegf8q4qkqbtz6nse8jebsqtxi4m4t X-HE-Tag: 1781842280-181056 X-HE-Meta: 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 7o9XHjM5 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Kairui Song writes: > On Fri, Jun 12, 2026 at 11:39:15PM +0800, Ritesh Harjani (IBM) wrote: >> On PowerPC Book3S64, MMU is selected at runtime, so macros like >> PMD_SHIFT are effectively runtime variables in the Book3S64 code. THP >> swap code uses these macros to size some of its array data structures >> based on PMD_ORDER e.g. SWAPFILE_CLUSTER macro is used for this very >> purpose. >> Hence this patch initializes SWAPFILE_CLUSTER at runtime and also >> modifies swap_table and swap_memcg_table which were earlier using this >> macro for defining the number of table entries. >> >> Signed-off-by: Ritesh Harjani (IBM) >> --- >> mm/swap.h | 5 +++-- >> mm/swap_table.h | 6 ++---- >> mm/swapfile.c | 27 ++++++++++++++++++++++----- >> 3 files changed, 27 insertions(+), 11 deletions(-) > > Hi Ritesh, > > Thanks for the patch. > Thanks Kairui for taking a look at this. Sorry about the delayed response, (was on travel to #OSSMumbai). >> >> diff --git a/mm/swap.h b/mm/swap.h >> index 77d2d14eda42..956879a69ddd 100644 >> --- a/mm/swap.h >> +++ b/mm/swap.h >> @@ -26,11 +26,12 @@ extern int page_cluster; >> #define SWAP_TABLE_HAS_ZEROFLAG ((BITS_PER_LONG - SWAP_CACHE_PFN_MARK_BITS - \ >> SWAP_CACHE_PFN_BITS) > SWAP_COUNT_MIN_BITS) >> >> +extern unsigned int swap_slots_in_cluster __read_mostly; > > Maybe __ro_after_init is better for this kind of use case? > yup. I can change that. >> +#define SWAPFILE_CLUSTER swap_slots_in_cluster >> + >> #ifdef CONFIG_THP_SWAP >> -#define SWAPFILE_CLUSTER HPAGE_PMD_NR > > So on Book3S64, HPAGE_PMD_NR is also a variable right? Then we don't really > need to change the SWAPFILE_CLUSTER defination here? We just need to adjust > the users of this macro so the build will pass? > Right. Earlier I was playing with different values of this via an arch_xxx variant. But for book3s64 usecase, the default values are fine. So, I agree, we need not change SWAPFILE_CLUSTER here. I can update the patch with the suggested changes in v4. -ritesh