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 4B85EC7EE2A for ; Thu, 26 Jun 2025 01:17:52 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 90C566B00B0; Wed, 25 Jun 2025 21:17:51 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 8BE416B00B7; Wed, 25 Jun 2025 21:17:51 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 7AC266B00BE; Wed, 25 Jun 2025 21:17:51 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) by kanga.kvack.org (Postfix) with ESMTP id 68FE56B00B0 for ; Wed, 25 Jun 2025 21:17:51 -0400 (EDT) Received: from smtpin11.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay04.hostedemail.com (Postfix) with ESMTP id 11D731A0301 for ; Thu, 26 Jun 2025 01:17:51 +0000 (UTC) X-FDA: 83595789942.11.F0402EF Received: from out-171.mta1.migadu.com (out-171.mta1.migadu.com [95.215.58.171]) by imf30.hostedemail.com (Postfix) with ESMTP id 14BC280004 for ; Thu, 26 Jun 2025 01:17:48 +0000 (UTC) Authentication-Results: imf30.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b="eQC/N5AQ"; spf=pass (imf30.hostedemail.com: domain of lance.yang@linux.dev designates 95.215.58.171 as permitted sender) smtp.mailfrom=lance.yang@linux.dev; dmarc=pass (policy=none) header.from=linux.dev ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1750900669; 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:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=+/mKaCqAOOiAqgd0HRwof3OK6yOq5hDWh6JBXZFbX3c=; b=grMkGRsEFxx2QvZtZ0cOFmwvbk7qCcttLWY23RTMv1UWVnibYpKQdpaIHkKYc18B0JZ3Yj 9L/VNXgHp/jjZyByD1+5c2ofDVxt+MzFkyOCJL0PDWjS1IOCknlV3C1s7NxtOT3KE7QiNv zX6OgJPgu/9jcjZ0QXKOfO8uRoZFkEo= ARC-Authentication-Results: i=1; imf30.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b="eQC/N5AQ"; spf=pass (imf30.hostedemail.com: domain of lance.yang@linux.dev designates 95.215.58.171 as permitted sender) smtp.mailfrom=lance.yang@linux.dev; dmarc=pass (policy=none) header.from=linux.dev ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1750900669; a=rsa-sha256; cv=none; b=Bh+KIKVOeJIQ6m0c/sI5V+uhjassnuZM/PUBRT/BR68G2Rev2uS3B1cgnDDozASkYAElaE sQMR9GClgOX5mFOCIbQCJ32VMfvaxcjjLtdHA+rFsdqrZw7X81lzFR6dA5mVkpNLSO90lW MGBLlvFv3CMAieTwxPD77d24qIL6wP0= Message-ID: <42343413-7089-404e-8ce0-dd0025dca04c@linux.dev> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1750900666; h=from:from: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:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=+/mKaCqAOOiAqgd0HRwof3OK6yOq5hDWh6JBXZFbX3c=; b=eQC/N5AQvanuC7OqZCZ2wPmyrZ0ioxCa9JUW83LYLMRJAjmHovEfQEFsrT0ybVpqok1KVf W8sl6sksNaJU2UyrQqwdsCkZ9XZzcI0M91ODFaE5+ns5n8ksfSxI1liRF/El6i+kpXAUkV hSNMrXxp+B00xFNqxmEmvAlnPyxAvY8= Date: Thu, 26 Jun 2025 09:17:33 +0800 MIME-Version: 1.0 Subject: Re: [PATCH v4 3/4] mm: Support batched unmap for lazyfree large folios during reclamation Content-Language: en-US To: Barry Song <21cnbao@gmail.com>, David Hildenbrand Cc: akpm@linux-foundation.org, baolin.wang@linux.alibaba.com, chrisl@kernel.org, kasong@tencent.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-riscv@lists.infradead.org, lorenzo.stoakes@oracle.com, ryan.roberts@arm.com, v-songbaohua@oppo.com, x86@kernel.org, ying.huang@intel.com, zhengtangquan@oppo.com, Lance Yang References: <2c19a6cf-0b42-477b-a672-ed8c1edd4267@redhat.com> <20250624162503.78957-1-ioworker0@gmail.com> <27d174e0-c209-4851-825a-0baeb56df86f@redhat.com> <938c4726-b93e-46df-bceb-65c7574714a6@linux.dev> <5ba95609-302b-456a-a863-2bd5df51baf2@redhat.com> <6179dd30-5351-4a79-b0d6-f0e85650a926@redhat.com> <5db6fb4c-079d-4237-80b3-637565457f39@redhat.com> <42f1d84f-2d17-43b7-8fa2-83322fcca44f@linux.dev> <9bb1e917-891d-4e1b-915f-98cdd5fc578b@redhat.com> X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Lance Yang In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 14BC280004 X-Stat-Signature: y9twp3okufcsygugojkxzm9h5npb61i4 X-HE-Tag: 1750900668-855628 X-HE-Meta: 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 Z1D62m4U c5cahHGa4SJot1R6gfjQMZpTKGH8lcQq39X9vzBexqa77FpbDr/1BX0eHoQlNy8jgjeb/ku70Fn7VR/aWCztN/Y/ItG1EQMbN2QEbmXdWuUJdBVGwXcAP5AHrxxDN7dJyzF9aRx81t9fZbtdC1uc6Fc6Ak65lXxYDJBYbWw0eq/n2JtvT+mMOvA5eEMtnKCU3mMCeQQmnVrdVeeuKrsKVXNeXKoF9aT9bpligwcv1oVT/t1E= 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: List-Subscribe: List-Unsubscribe: On 2025/6/26 05:03, Barry Song wrote: > On Thu, Jun 26, 2025 at 12:25 AM David Hildenbrand wrote: >> >> On 25.06.25 14:20, Lance Yang wrote: > [...] >>> Hmm... I have a question about the reference counting here ... >>> >>> if (vma->vm_flags & VM_LOCKED) >>> mlock_drain_local(); >>> folio_put(folio); >>> /* We have already batched the entire folio */ >>> >>> Does anyone else still hold a reference to this folio after folio_put()? >> >> The caller of the unmap operation should better hold a reference :) >> >> Also, I am not sure why we don't perform a >> >> folio_put_refs(folio, nr_pages); > > Because we've already called folio_ref_sub(folio, nr_pages - 1); > Looking back, it’s kind of ugly, huh. > > discard: > if (unlikely(folio_test_hugetlb(folio))) { > hugetlb_remove_rmap(folio); > } else { > folio_remove_rmap_ptes(folio, subpage, nr_pages, vma); > folio_ref_sub(folio, nr_pages - 1); > } > > I assume Lance will send a patch? If so, remember to remove this > when switching to folio_put_refs(folio, nr_pages); Ah, got it. Thanks for pointing that out!