From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0FD9132B124 for ; Thu, 2 Jul 2026 16:03:57 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783008238; cv=none; b=hbcoJzn1sXrHUols3S2Yv1O2NZkJfr0Z3yyjm1xDk3WfYLr3aCeJ/pDbxzdcAxg/ni28xREixJkwYVnW+1JLFHC26gouQBeFJePMKFmi6AyOskph1FDhXf1/DcGjnhCOYKfmA88RNWhzgkbku3S2EqJQptphEpc/YaBcz3got74= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783008238; c=relaxed/simple; bh=NNUAesQWJsmzIG3Up18xlY+dS4t2LVqxOoXhw+d5LMQ=; h=Date:To:From:Subject:Message-Id; b=LDA6U0s2yTpBZh23KMD2tVg0vkkoPRHmQUsKWjGphNsrQV2wyvOVjDHUNhOORDYgb+e3k2xRGCJ7jo7f2QKfnilwm0BlBRnC+BPm/VAsuVN8uEkwoq3W8nllBL8kfIN0QthoSPekFmYe8+bCzKKBfXDfipyOCgH5gGX63fTQEok= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=UZqi28uR; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="UZqi28uR" Received: by smtp.kernel.org (Postfix) with ESMTPSA id DABCF1F00A3A; Thu, 2 Jul 2026 16:03:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux-foundation.org; s=korg; t=1783008237; bh=UN89C+EfZMT+T1j36+Vkn0Z1aJUKv73EUzFDEB8+Wiw=; h=Date:To:From:Subject; b=UZqi28uRPZZIQGFxFVGMiBttzgXX3jiBduxSAvJKgWX43FdbA6+1EmZW5NLxYLAWj soI0TWNzgSMf+vyb8is6HlcR8c2qj1A+Vpl61qHYCDQIkhOhjtS/mZisF16FO/hrbm V4KeCUkjrr1n/qHBiPJWIbzmnjJ8ZEqZwNt3ge74= Date: Thu, 02 Jul 2026 09:03:56 -0700 To: mm-commits@vger.kernel.org,lizhe.67@bytedance.com,akpm@linux-foundation.org From: Andrew Morton Subject: [to-be-updated] mm-use-memcpy_nt-in-zone-device-template-copies.patch removed from -mm tree Message-Id: <20260702160356.DABCF1F00A3A@smtp.kernel.org> Precedence: bulk X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The quilt patch titled Subject: mm: use memcpy_nt() in zone-device template copies has been removed from the -mm tree. Its filename was mm-use-memcpy_nt-in-zone-device-template-copies.patch This patch was dropped because an updated version will be issued ------------------------------------------------------ From: "Li Zhe" Subject: mm: use memcpy_nt() in zone-device template copies Date: Wed, 1 Jul 2026 17:05:53 +0800 The template fast path currently uses memcpy() for the actual struct page copy. Switch zone_device_page_init_from_template() to memcpy_nt() and add memcpy_nt_drain() before memmap_init_compound(), before prep_compound_head() updates overlapping tail metadata, and before returning from memmap_init_zone_device(). ZONE_DEVICE memmap initialization is largely write-once: each struct page is populated once, and most destination cachelines are not expected to be reused immediately afterwards. On x86, a regular cached memcpy() can therefore incur write-allocate traffic by pulling destination cachelines into the cache before writeback, and can populate the cache with data that has little near-term reuse. Using memcpy_nt() lets this path request non-temporal stores for that copy pattern, which can reduce cache pollution and avoid part of the associated write-allocate overhead, while architectures without a specialized backend still fall back to memcpy(). When memcpy_nt() maps to non-temporal stores, order those stores before memmap_init_compound(), before prep_compound_head() updates overlapping compound metadata, and before returning from memmap_init_zone_device(). Keep sanitized builds on the slow path so KASAN/KMSAN retain their instrumented stores. Tested in a VM with a 100 GB fsdax namespace device configured with map=dev and a 100 GB devdax namespace (align=2097152) on Intel Ice Lake server. Test procedure: Rebind the nd_pmem and dax_pmem driver 30 times and collect the memmap initialization time from the pr_debug() output of memmap_init_zone_device(). Base(v7.2-rc1): First binding for nd_pmem driver: 1456 ms Average of subsequent rebinds: 244.28 ms First binding for dax_pmem driver: 1462 ms Average of subsequent rebinds: 273.31 ms With this series: First binding for nd_pmem driver: 1272 ms Average of subsequent rebinds: 96.79 ms First binding for dax_pmem driver: 1354 ms Average of subsequent rebinds: 119.04 ms This reduces the average rebind time by about 60.4% for nd_pmem and 56.4% for dax_pmem. Link: https://lore.kernel.org/20260701090553.62691-9-lizhe.67@bytedance.com Signed-off-by: Li Zhe Cc: Alistair Popple Cc: Arnd Bergmann Cc: Balbir Singh Cc: "Borislav Petkov (AMD)" Cc: David Hildenbrand Cc: Ingo Molnar Cc: Kees Cook Cc: Mike Rapoport (Microsoft) Signed-off-by: Andrew Morton --- mm/mm_init.c | 39 +++++++++++++++++++++++++++++++++++++-- 1 file changed, 37 insertions(+), 2 deletions(-) --- a/mm/mm_init.c~mm-use-memcpy_nt-in-zone-device-template-copies +++ a/mm/mm_init.c @@ -1059,10 +1059,20 @@ static void __ref zone_device_page_init_ static inline bool zone_device_page_init_optimization_enabled(void) { /* + * Keep sanitized builds on the slow path so their stores stay + * instrumented. + */ + if (IS_ENABLED(CONFIG_KASAN) || IS_ENABLED(CONFIG_KMSAN)) + return false; + + /* * The template fast path copies a preinitialized struct page image. * Skip it when the page_ref_set tracepoint is enabled. */ - return !page_ref_tracepoint_active(page_ref_set); + if (page_ref_tracepoint_active(page_ref_set)) + return false; + + return true; } static inline void zone_device_template_page_init(struct page *template, @@ -1107,7 +1117,7 @@ static void zone_device_page_init_from_t * to the destination page. */ zone_device_page_update_template(template, pfn); - memcpy(page, template, sizeof(*page)); + memcpy_nt(page, template, sizeof(*page)); } /* @@ -1178,6 +1188,15 @@ static void __ref memmap_init_compound(s zone_device_tail_page_init(page, pfn, zone_idx, nid, pgmap, head, order); } + + /* + * When the template path is enabled, order the preceding tail-page copies + * before prep_compound_head() updates the overlapping compound metadata + * in the first tail-page descriptors. If memcpy_nt() fell back to + * regular cached stores, memcpy_nt_drain() may be a no-op. + */ + if (use_template) + memcpy_nt_drain(); prep_compound_head(head, order); } @@ -1247,10 +1266,26 @@ void __ref memmap_init_zone_device(struc if (pfns_per_compound == 1) continue; + /* + * When the template path is enabled, order the preceding head-page copy + * before memmap_init_compound(), which immediately updates compound-head + * metadata. If memcpy_nt() fell back to regular cached stores, + * memcpy_nt_drain() may be a no-op. + */ + if (use_template) + memcpy_nt_drain(); + memmap_init_compound(page, pfn, zone_idx, nid, pgmap, compound_nr_pages(pfn, altmap, pgmap), use_template); } + /* + * Ensure any prior template copies are ordered before returning. + * On architectures where memcpy_nt() used regular cached stores, + * memcpy_nt_drain() may be a no-op. + */ + if (use_template) + memcpy_nt_drain(); pageblock_migratetype_init_range(start_pfn, nr_pages, MIGRATE_MOVABLE, false); _ Patches currently in -mm which might be from lizhe.67@bytedance.com are