From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 427C2C6FA82 for ; Fri, 23 Sep 2022 07:53:07 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id B190680009; Fri, 23 Sep 2022 03:53:06 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id AA24C80007; Fri, 23 Sep 2022 03:53:06 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 91B3680009; Fri, 23 Sep 2022 03:53:06 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id 7C95C80007 for ; Fri, 23 Sep 2022 03:53:06 -0400 (EDT) Received: from smtpin07.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay07.hostedemail.com (Postfix) with ESMTP id 4B891160CF7 for ; Fri, 23 Sep 2022 07:53:06 +0000 (UTC) X-FDA: 79942584372.07.641291C Received: from mga04.intel.com (mga04.intel.com [192.55.52.120]) by imf30.hostedemail.com (Postfix) with ESMTP id 6A3DF80006 for ; Fri, 23 Sep 2022 07:53:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1663919585; x=1695455585; h=from:to:cc:subject:references:date:in-reply-to: message-id:mime-version; bh=RRq3GIYX0K2ybEJZ1gFU38FbFEL6Oayfi9B31K5s1kU=; b=nelqMltBKoFLKK4w9+rlv3S5q75hv223ohSGpbQuCHTBkjDcecdirnlo NDIGiZnQsG8aj+tb9RwZ3v9amhNcr/58ILz9PYMB/lWXOU+Yh/p2AL7S5 vik8NGhpKVQXtDzJm4Oc5gUq4bAMcnwkxdDkdOXW0NRWMQZfpFcSPglwh epQo2FbbDDQFMtky38s5Jv7OpPlZ55hU6iQDnvpZtbkIGk9pWNgYFAeNR hINmUQUrSsJWSK9pHonaI9zmJVL0NbMiPEoinoOKB2VNrHm6q3nEIcmqe E96jMUVQEjMdv3OBfkJ/6NpDK9yhkAcODk0+7ZOHFRcCmI/HhY6qrViZr Q==; X-IronPort-AV: E=McAfee;i="6500,9779,10478"; a="299258296" X-IronPort-AV: E=Sophos;i="5.93,337,1654585200"; d="scan'208";a="299258296" Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by fmsmga104.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 23 Sep 2022 00:53:03 -0700 X-IronPort-AV: E=Sophos;i="5.93,337,1654585200"; d="scan'208";a="762530091" Received: from yhuang6-desk2.sh.intel.com (HELO yhuang6-desk2.ccr.corp.intel.com) ([10.238.208.55]) by fmsmga001-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 23 Sep 2022 00:53:01 -0700 From: "Huang, Ying" To: Bharata B Rao Cc: , , Andrew Morton , Zi Yan , Yang Shi , Baolin Wang , Oscar Salvador , "Matthew Wilcox" Subject: Re: [RFC 0/6] migrate_pages(): batch TLB flushing References: <20220921060616.73086-1-ying.huang@intel.com> <477e50ab-9045-0ca2-6979-e2dca71be263@amd.com> Date: Fri, 23 Sep 2022 15:52:52 +0800 In-Reply-To: <477e50ab-9045-0ca2-6979-e2dca71be263@amd.com> (Bharata B. Rao's message of "Thu, 22 Sep 2022 18:20:28 +0530") Message-ID: <87bkr6jzmz.fsf@yhuang6-desk2.ccr.corp.intel.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=ascii ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1663919586; a=rsa-sha256; cv=none; b=I04Ho56XR4fxSg+/djlP2/lFWj9/LVF+slHXLLXU5cRRKcjZ/ovKyskCVDtlWDbCNgQj2k BEfzr+zWPyOFPcrXIEINBlUrOMZ6BSbs0QLzpbCyPDgtlpjf9GtQxVaErrKxBps320jKAG iAxDLIkODfk+VxOYAaPkTLGGdkNkI+8= ARC-Authentication-Results: i=1; imf30.hostedemail.com; dkim=none ("invalid DKIM record") header.d=intel.com header.s=Intel header.b=nelqMltB; spf=pass (imf30.hostedemail.com: domain of ying.huang@intel.com designates 192.55.52.120 as permitted sender) smtp.mailfrom=ying.huang@intel.com; dmarc=pass (policy=none) header.from=intel.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1663919586; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=Xx4Y6jhjCG0egUZbnlzhK9v0IdFRf1dImu/OlVOzvUc=; b=FM+Z1/bByZhD3CSlHQ1A1EISQerItGnJcJrWKKrhiue+BgHv3VXWpQe1hxEnvNFWJp+Y82 SsecWmBFXR+rZUr13s9kOWOhgAE+arx3jkxTFGIYm+BTrE8yd4ECbgo+qwWH8R77Ah2C4P 5Vt8baH29gvE36Bm61se3Pzpw3TwVPM= X-Stat-Signature: 4hrxeorueme6rby5j8wpdck4dg6wt6u7 X-Rspamd-Queue-Id: 6A3DF80006 X-Rspam-User: X-Rspamd-Server: rspam08 Authentication-Results: imf30.hostedemail.com; dkim=none ("invalid DKIM record") header.d=intel.com header.s=Intel header.b=nelqMltB; spf=pass (imf30.hostedemail.com: domain of ying.huang@intel.com designates 192.55.52.120 as permitted sender) smtp.mailfrom=ying.huang@intel.com; dmarc=pass (policy=none) header.from=intel.com X-HE-Tag: 1663919585-128788 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Bharata B Rao writes: > On 9/21/2022 11:36 AM, Huang Ying wrote: >> From: "Huang, Ying" >> >> Now, migrate_pages() migrate pages one by one, like the fake code as >> follows, >> >> for each page >> unmap >> flush TLB >> copy >> restore map >> >> If multiple pages are passed to migrate_pages(), there are >> opportunities to batch the TLB flushing and copying. That is, we can >> change the code to something as follows, >> >> for each page >> unmap >> for each page >> flush TLB >> for each page >> copy >> for each page >> restore map >> >> The total number of TLB flushing IPI can be reduced considerably. And >> we may use some hardware accelerator such as DSA to accelerate the >> page copying. >> >> So in this patch, we refactor the migrate_pages() implementation and >> implement the TLB flushing batching. Base on this, hardware >> accelerated page copying can be implemented. >> >> If too many pages are passed to migrate_pages(), in the naive batched >> implementation, we may unmap too many pages at the same time. The >> possibility for a task to wait for the migrated pages to be mapped >> again increases. So the latency may be hurt. To deal with this >> issue, the max number of pages be unmapped in batch is restricted to >> no more than HPAGE_PMD_NR. That is, the influence is at the same >> level of THP migration. > > Thanks for the patchset. I find it hitting the following BUG() when > running mmtests/autonumabench: > > kernel BUG at mm/migrate.c:2432! > invalid opcode: 0000 [#1] PREEMPT SMP NOPTI > CPU: 7 PID: 7150 Comm: numa01 Not tainted 6.0.0-rc5+ #171 > Hardware name: Dell Inc. PowerEdge R6525/024PW1, BIOS 2.5.6 10/06/2021 > RIP: 0010:migrate_misplaced_page+0x670/0x830 > Code: 36 48 8b 3c c5 e0 7a 19 8d e8 dc 10 f7 ff 4c 89 e7 e8 f4 43 f5 ff 8b 55 bc 85 d2 75 6f 48 8b 45 c0 4c 39 e8 0f 84 b0 fb ff ff <0f> 0b 48 8b 7d 90 e9 ec fc ff ff 48 83 e8 01 e9 48 fa ff ff 48 83 > RSP: 0000:ffffb1b29ec3fd38 EFLAGS: 00010202 > RAX: ffffe946460f8248 RBX: 0000000000000001 RCX: ffffe946460f8248 > RDX: 0000000000000000 RSI: ffffe946460f8248 RDI: ffffb1b29ec3fce0 > RBP: ffffb1b29ec3fda8 R08: 0000000000000000 R09: 0000000000000005 > R10: 0000000000000001 R11: 0000000000000000 R12: ffffe946460f8240 > R13: ffffb1b29ec3fd68 R14: 0000000000000001 R15: ffff9698beed5000 > FS: 00007fcc31fee640(0000) GS:ffff9697b0000000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 00007fcc3a3a5000 CR3: 000000016e89c002 CR4: 0000000000770ee0 > PKRU: 55555554 > Call Trace: > > __handle_mm_fault+0xb87/0xff0 > handle_mm_fault+0x126/0x3c0 > do_user_addr_fault+0x1ed/0x690 > exc_page_fault+0x84/0x2c0 > asm_exc_page_fault+0x27/0x30 > RIP: 0033:0x7fccfa1a1180 > Code: 81 fa 80 00 00 00 76 d2 c5 fe 7f 40 40 c5 fe 7f 40 60 48 83 c7 80 48 81 fa 00 01 00 00 76 2b 48 8d 90 80 00 00 00 48 83 e2 c0 fd 7f 02 c5 fd 7f 42 20 c5 fd 7f 42 40 c5 fd 7f 42 60 48 83 ea > RSP: 002b:00007fcc31fede38 EFLAGS: 00010283 > RAX: 00007fcc39fff010 RBX: 000000000000002c RCX: 00007fccfa11ea3d > RDX: 00007fcc3a3a5000 RSI: 0000000000000000 RDI: 00007fccf9ffef90 > RBP: 00007fcc39fff010 R08: 00007fcc31fee640 R09: 00007fcc31fee640 > R10: 00007ffdecef614f R11: 0000000000000246 R12: 00000000c0000000 > R13: 0000000000000000 R14: 00007fccfa094850 R15: 00007ffdecef6190 > > This is BUG_ON(!list_empty(&migratepages)) in migrate_misplaced_page(). Thank you very much for reporting! I haven't reproduced this yet. But I will pay special attention to this when develop the next version, even if I cannot reproduce this finally. Best Regards, Huang, Ying