From patchwork Thu Oct 5 18:31:38 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Verma, Vishal L" X-Patchwork-Id: 13410617 Received: from mgamail.intel.com (mgamail.intel.com [192.55.52.151]) (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 900BB3FB25 for ; Thu, 5 Oct 2023 18:32:00 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="LPghufRX" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1696530720; x=1728066720; h=from:subject:date:message-id:mime-version: content-transfer-encoding:to:cc; bh=/oSquPe50FjL5XM1xo2u1juCDXoKE0v8k5E8iBZtEIw=; b=LPghufRXgmW+FpkS+XZa3l4lxugkUkTdnijw03C1lR6U0JTV+wXIa6no EFEWvIOVNcWpLWR/mTLybgIR74zYc2cQtGpP89yvZS4w6nAviMjh1bAhR iaPAhOwj2ec/uYNEnlrm8HLy4cZbSCoZ6fv0mvWLaUc/fY/K2/ud3EVMF q9wB7O8sVtb+bgXl5v5lF5UvoUWdaAlceq/aoYOqshHPBP5gLoFVJWurD w3SJBPE94tsM1rUknPPPMuKpsag5YD4/6hiJBhJnvjFDlQXgfJIvIlJec MlahbTJts7hswlqBZNqYE13F8QwDLC9MNouhu9c/eQDLnTIky6CvTHOYd Q==; X-IronPort-AV: E=McAfee;i="6600,9927,10854"; a="363860722" X-IronPort-AV: E=Sophos;i="6.03,203,1694761200"; d="scan'208";a="363860722" Received: from orsmga008.jf.intel.com ([10.7.209.65]) by fmsmga107.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 05 Oct 2023 11:31:53 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10854"; a="781342809" X-IronPort-AV: E=Sophos;i="6.03,203,1694761200"; d="scan'208";a="781342809" Received: from amykuo-mobl.amr.corp.intel.com (HELO [192.168.1.200]) ([10.212.12.247]) by orsmga008-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 05 Oct 2023 11:31:52 -0700 From: Vishal Verma Subject: [PATCH v5 0/2] mm: use memmap_on_memory semantics for dax/kmem Date: Thu, 05 Oct 2023 12:31:38 -0600 Message-Id: <20231005-vv-kmem_memmap-v5-0-a54d1981f0a3@intel.com> Precedence: bulk X-Mailing-List: nvdimm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-B4-Tracking: v=1; b=H4sIAAoBH2UC/3XNQW7DIBAF0KtErEuFAWPIqveoomqMhxrVxhEkq FXku3eSjatYXczif+n9ubGCOWJhx8ONZayxxCVRaF8OzI+QPpHHgTKTQiphGsVr5V8zzh90M5x 5q63ydhBado4R6qEg7zMkPxJL12mi8pwxxO/Hl/cT5TGWy5J/Hk9rc2//3a8NFzyYAZ03EKQ3b zFdcHr1y8zuU1VuvJNixyVxa/sBoFfaOfXM1cataHZcEdfCoAMIrbHumeuNO2l3XBM3IXQqoG8 bB3/5uq6/ecPnLX4BAAA= To: Andrew Morton , David Hildenbrand , Oscar Salvador , Dan Williams , Dave Jiang Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, nvdimm@lists.linux.dev, linux-cxl@vger.kernel.org, Huang Ying , Dave Hansen , "Aneesh Kumar K.V" , Michal Hocko , Jonathan Cameron , Jeff Moyer , Vishal Verma , Jonathan Cameron X-Mailer: b4 0.12.3 X-Developer-Signature: v=1; a=openpgp-sha256; l=3836; i=vishal.l.verma@intel.com; h=from:subject:message-id; bh=/oSquPe50FjL5XM1xo2u1juCDXoKE0v8k5E8iBZtEIw=; b=owGbwMvMwCXGf25diOft7jLG02pJDKnyjMLySb8bv+wJd3nTr7TeqNDswTLnqZtspXept0Se3 sM9+1lwRykLgxgXg6yYIsvfPR8Zj8ltz+cJTHCEmcPKBDKEgYtTACZi8p3hf3LZ3uDd+/aeZPnw 4uZs5ow39yy/rQhZpegvfPizImvNhVMMf/j7d/7VfaqYvV1hoXrIRcachTsOW1w/+1DVZFvQnW3 HzDgA X-Developer-Key: i=vishal.l.verma@intel.com; a=openpgp; fpr=F8682BE134C67A12332A2ED07AFA61BEA3B84DFF The dax/kmem driver can potentially hot-add large amounts of memory originating from CXL memory expanders, or NVDIMMs, or other 'device memories'. There is a chance there isn't enough regular system memory available to fit the memmap for this new memory. It's therefore desirable, if all other conditions are met, for the kmem managed memory to place its memmap on the newly added memory itself. The main hurdle for accomplishing this for kmem is that memmap_on_memory can only be done if the memory being added is equal to the size of one memblock. To overcome this, allow the hotplug code to split an add_memory() request into memblock-sized chunks, and try_remove_memory() to also expect and handle such a scenario. Patch 1 teaches the memory_hotplug code to allow for splitting add_memory() and remove_memory() requests over memblock sized chunks. Patch 2 adds a sysfs control for the kmem driver that would allow an opt-out of using memmap_on_memory for the memory being added. Signed-off-by: Vishal Verma --- Changes in v5: - Separate out per-memblock operations from per memory block operations in try_remove_memory(), and rename the inner function appropriately. This does expand the scope of the memory hotplug lock to include remove_memory_block_devices(), but the alternative was to drop the lock in the inner function separately for each iteration, and then re-acquire it in try_remove_memory() creating a small window where the lock isn't held. (David Hildenbrand) - Remove unnecessary rc check from the memmap_on_memory_store sysfs helper in patch 2 (Dan Carpenter) - Link to v4: https://lore.kernel.org/r/20230928-vv-kmem_memmap-v4-0-6ff73fec519a@intel.com Changes in v4: - Rebase to Aneesh's PPC64 memmap_on_memory series v8 [2]. - Tweak a goto / error path in add_memory_create_devices() (Jonathan) - Retain the old behavior for dax devices, only default to memmap_on_memory for CXL (Jonathan) - Link to v3: https://lore.kernel.org/r/20230801-vv-kmem_memmap-v3-0-406e9aaf5689@intel.com [2]: https://lore.kernel.org/linux-mm/20230808091501.287660-1-aneesh.kumar@linux.ibm.com Changes in v3: - Rebase on Aneesh's patches [1] - Drop Patch 1 - it is not needed since [1] allows for dynamic setting of the memmap_on_memory param (David) - Link to v2: https://lore.kernel.org/r/20230720-vv-kmem_memmap-v2-0-88bdaab34993@intel.com [1]: https://lore.kernel.org/r/20230801044116.10674-1-aneesh.kumar@linux.ibm.com Changes in v2: - Drop the patch to create an override path for the memmap_on_memory module param (David) - Move the chunking into memory_hotplug.c so that any caller of add_memory() can request this behavior. (David) - Handle remove_memory() too. (David, Ying) - Add a sysfs control in the kmem driver for memmap_on_memory semantics (David, Jonathan) - Add a #else case to define mhp_supports_memmap_on_memory() if CONFIG_MEMORY_HOTPLUG is unset. (0day report) - Link to v1: https://lore.kernel.org/r/20230613-vv-kmem_memmap-v1-0-f6de9c6af2c6@intel.com --- Vishal Verma (2): mm/memory_hotplug: split memmap_on_memory requests across memblocks dax/kmem: allow kmem to add memory with memmap_on_memory drivers/dax/bus.h | 1 + drivers/dax/dax-private.h | 1 + drivers/dax/bus.c | 38 +++++++++++ drivers/dax/cxl.c | 1 + drivers/dax/hmem/hmem.c | 1 + drivers/dax/kmem.c | 8 ++- drivers/dax/pmem.c | 1 + mm/memory_hotplug.c | 162 ++++++++++++++++++++++++++++------------------ 8 files changed, 149 insertions(+), 64 deletions(-) --- base-commit: 25b5b1a0646c3d39e1d885e27c10be1c9e202bf2 change-id: 20230613-vv-kmem_memmap-5483c8d04279 Best regards,