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]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 1419ACD8C8E for ; Mon, 8 Jun 2026 04:34:48 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 554D26B008C; Mon, 8 Jun 2026 00:34:48 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 50AD46B0092; Mon, 8 Jun 2026 00:34:48 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 3F3E76B0093; Mon, 8 Jun 2026 00:34:48 -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 2CEF16B008C for ; Mon, 8 Jun 2026 00:34:48 -0400 (EDT) Received: from smtpin15.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay09.hostedemail.com (Postfix) with ESMTP id C1D4691411 for ; Mon, 8 Jun 2026 04:34:47 +0000 (UTC) X-FDA: 84855479814.15.120731D Received: from out-171.mta1.migadu.com (out-171.mta1.migadu.com [95.215.58.171]) by imf03.hostedemail.com (Postfix) with ESMTP id DDAA920004 for ; Mon, 8 Jun 2026 04:34:45 +0000 (UTC) Authentication-Results: imf03.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=VPOCIBhM; dmarc=pass (policy=none) header.from=linux.dev; spf=pass (imf03.hostedemail.com: domain of lance.yang@linux.dev designates 95.215.58.171 as permitted sender) smtp.mailfrom=lance.yang@linux.dev ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1780893286; 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=LEGSgRbxhASAeu5c+j0JYp3vSZy8pgb96WObfdHnflg=; b=PlB5wmbBmyxDARHHAfyOf4NHrt3y88uD05ziBSFVE2pmT0UIZIIFqKz8FL/GlNXQ3O+gcO fyxoKElBvaRjlxTfxdLNDiGeUSsaMByaGca4ZIpuOOm2GZ3Dw/Aq7ZKIbmWK9misAB922E MQ1/w5rjq7nkp8jM+6VptPulwN1iEz4= ARC-Authentication-Results: i=1; imf03.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=VPOCIBhM; dmarc=pass (policy=none) header.from=linux.dev; spf=pass (imf03.hostedemail.com: domain of lance.yang@linux.dev designates 95.215.58.171 as permitted sender) smtp.mailfrom=lance.yang@linux.dev ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1780893286; b=G+jHu0PpHIzOg8nfkpvs9cpkCqxQwB+jKpxrFparualv0wXFTkJNxD8wu4GR1WsJmppklH qNdZo+IRs9vHME5VUrsFTtTA0Xntn6pxgLxgVrZHqQ2C3nnAUMIevEQGnF7MZZhgpLmORR 76XCh66YK9Agpc1yZ5pZuQaop6zRCLo= X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1780893281; 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=LEGSgRbxhASAeu5c+j0JYp3vSZy8pgb96WObfdHnflg=; b=VPOCIBhMy3bhMys4tjIwpTNUtzP6MGv+Nn6NObx2oWwjAimmM3rk21c2FPdqpv4YaDBpr6 0+eQK5sDLTwER1nbC9LUzt9Lo5gKkA2lIBYpEHSVZAfPNQXBG+/72ec7a4XSNLj89zDlRT 6qmoBbe0Ok0yW6VRRc/UfKW3DXnFbbc= From: Lance Yang To: npache@redhat.com Cc: linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-trace-kernel@vger.kernel.org, aarcange@redhat.com, akpm@linux-foundation.org, anshuman.khandual@arm.com, apopple@nvidia.com, baohua@kernel.org, baolin.wang@linux.alibaba.com, byungchul@sk.com, catalin.marinas@arm.com, cl@gentwo.org, corbet@lwn.net, dave.hansen@linux.intel.com, david@kernel.org, dev.jain@arm.com, gourry@gourry.net, hannes@cmpxchg.org, hughd@google.com, jack@suse.cz, jackmanb@google.com, jannh@google.com, jglisse@google.com, joshua.hahnjy@gmail.com, kas@kernel.org, lance.yang@linux.dev, liam@infradead.org, ljs@kernel.org, mathieu.desnoyers@efficios.com, matthew.brost@intel.com, mhiramat@kernel.org, mhocko@suse.com, peterx@redhat.com, pfalcato@suse.de, rakie.kim@sk.com, raquini@redhat.com, rdunlap@infradead.org, richard.weiyang@gmail.com, rientjes@google.com, rostedt@goodmis.org, rppt@kernel.org, ryan.roberts@arm.com, shivankg@amd.com, sunnanyong@huawei.com, surenb@google.com, thomas.hellstrom@linux.intel.com, tiwai@suse.de, usamaarif642@gmail.com, vbabka@suse.cz, vishal.moola@gmail.com, wangkefeng.wang@huawei.com, will@kernel.org, willy@infradead.org, yang@os.amperecomputing.com, ying.huang@linux.alibaba.com, ziy@nvidia.com, zokeefe@google.com Subject: Re: [PATCH mm-unstable v19 05/14] mm/khugepaged: require collapse_huge_page to enter/exit with the lock dropped Date: Mon, 8 Jun 2026 12:34:24 +0800 Message-Id: <20260608043424.55432-1-lance.yang@linux.dev> In-Reply-To: <20260605161422.213817-6-npache@redhat.com> References: <20260605161422.213817-6-npache@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: DDAA920004 X-Stat-Signature: fh77krurztgjtfs9uztckiqqfhp6w4nu X-Rspam-User: X-HE-Tag: 1780893285-991559 X-HE-Meta: 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 W5n1T9NK Zs/G8Ig5Sf9Ro+zK1GDYbKJIxnC9VkGXsF/KucgMt6eOR99vT+s2RMbxu51sfulpJmYgq/4/9RwyuYtzVGhqeBtxkEJwVPL0ZHueG7LLnUnYUwQXS0vapdoi1coGyBLa3rvUxQwdfgMhLbVksKz1DyA6djdNxT/7O1y/GIszDjEZXrF0QhCVCsIDoI4QUqo7wcWLzjo7mEkbhg3hF6ga1wNpEuMJ2nzVd5yE0c6CRMFtAaN8qYJnBtx2oDdev1roK8MQvb0LbxYRw0FvN3uzUC6C2JKfgRfLAJLVZF8jDFyYxktFFRCRCxpWnx96IGI+XijzvV99gde+dkjvRCQAE0jY58C4l+QL9qUsE1rnZ4eIT+775COc5uJGBfQ== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, Jun 05, 2026 at 10:14:12AM -0600, Nico Pache wrote: >Currently the collapse_huge_page function requires the mmap_read_lock to >enter with it held, and exit with it dropped. This function moves the >unlock into its parent caller, and changes this semantic to requiring it >to enter/exit with it always unlocked. > >In future patches, we need this expectation, as for in mTHP collapse, we >may have already dropped the lock, and do not want to conditionally >check for this by passing through the lock_dropped variable. > >No functional change is expected as one of the first things the >collapse_huge_page function does is drop this lock before allocating the >hugepage. > >Reviewed-by: Lorenzo Stoakes >Acked-by: David Hildenbrand (Arm) >Signed-off-by: Nico Pache >--- Reviewed-by: Lance Yang