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 683F9D3C542 for ; Fri, 18 Oct 2024 02:23:51 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 6D70F6B0082; Thu, 17 Oct 2024 22:23:50 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 6876A6B0083; Thu, 17 Oct 2024 22:23:50 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 500906B0085; Thu, 17 Oct 2024 22:23:50 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0014.hostedemail.com [216.40.44.14]) by kanga.kvack.org (Postfix) with ESMTP id 321446B0082 for ; Thu, 17 Oct 2024 22:23:50 -0400 (EDT) Received: from smtpin03.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay04.hostedemail.com (Postfix) with ESMTP id 1335F1A16CC for ; Fri, 18 Oct 2024 02:23:29 +0000 (UTC) X-FDA: 82685126916.03.42E7048 Received: from mail-pj1-f44.google.com (mail-pj1-f44.google.com [209.85.216.44]) by imf12.hostedemail.com (Postfix) with ESMTP id DC8DD40012 for ; Fri, 18 Oct 2024 02:23:42 +0000 (UTC) Authentication-Results: imf12.hostedemail.com; dkim=pass header.d=bytedance.com header.s=google header.b=XbtI0XWG; spf=pass (imf12.hostedemail.com: domain of zhengqi.arch@bytedance.com designates 209.85.216.44 as permitted sender) smtp.mailfrom=zhengqi.arch@bytedance.com; dmarc=pass (policy=quarantine) header.from=bytedance.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1729218153; a=rsa-sha256; cv=none; b=k/OJwfC+O6UiKSma1OFxd2YY+vkz/dXagd34leHxtrFx2CAMqby8kqAj7FUXr5FUrDVyx1 0Us6iE3A3eWTxK+fOp8iUSlPSeXZ9CJABRidOL4wI4UxXaM93FmnmSEwj0Uf+/8rH4d8Ck SGPvzPQtowWZ+6oquBmwPS19orxDTEQ= ARC-Authentication-Results: i=1; imf12.hostedemail.com; dkim=pass header.d=bytedance.com header.s=google header.b=XbtI0XWG; spf=pass (imf12.hostedemail.com: domain of zhengqi.arch@bytedance.com designates 209.85.216.44 as permitted sender) smtp.mailfrom=zhengqi.arch@bytedance.com; dmarc=pass (policy=quarantine) header.from=bytedance.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1729218153; 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=pWdd9RuQD9OT8IO+IFQorkG8tJKWR5GHHBm0b+278DM=; b=cDG2ahU/YETkzoQD032BYDq8QlzOtlyJQv5wL0elmSm4iHHwGf4dAzYfbxWZTwz76gizLS Lcup0zzhshPac9zjk/HMn/Ydl6KgARP2zLcv3HQDYcqXDCbleTVktUrFGRfTeaHhDEckU/ YIzZGX/bVuPLZL0ll3IXR1nyVfcQJq8= Received: by mail-pj1-f44.google.com with SMTP id 98e67ed59e1d1-2e2e88cb0bbso1174551a91.3 for ; Thu, 17 Oct 2024 19:23:47 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bytedance.com; s=google; t=1729218226; x=1729823026; darn=kvack.org; h=content-transfer-encoding:in-reply-to:from:references:cc:to :content-language:subject:user-agent:mime-version:date:message-id :from:to:cc:subject:date:message-id:reply-to; bh=pWdd9RuQD9OT8IO+IFQorkG8tJKWR5GHHBm0b+278DM=; b=XbtI0XWGuGMfEtHfP4e7umPkqmti9hLzQ6KMpwGrpKutimXil1+kIxUaZ6A4H5/F/X x2VXHL64Ug0FZAoV01rp1rSLpxPpfTSsZnI/GATG1i5aep7G0PDZlHpcjfzrerNBDbzF aXxrGPD7Tvdju/yS1Cxv/raHqWQ4dgLdfiBQ/MgfdIAShOLtCm3lFnNYFhOJoWtykIG7 K84rJpVaI+QK/+rhLlOOkE98KErNjgnwAN1qIvj56twYftm7351v9gkG0Wo8rR49J5A+ d5eNnKULANjzJyAil8ZkFQXUrfRk6EVC7TahqqvnUvJZKY5b1mX8/vkuBKsKN3ekIqpF vXCg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1729218226; x=1729823026; h=content-transfer-encoding:in-reply-to:from:references:cc:to :content-language:subject:user-agent:mime-version:date:message-id :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=pWdd9RuQD9OT8IO+IFQorkG8tJKWR5GHHBm0b+278DM=; b=FQgB0gBB9js/D/sU+B8iuX7/DSNy3LAO4xeTSkoMIYYevET+koe5N7B+NgErJYSs+s GLt/YhrH57DX/2RhAxtfgaKwLV57aKIpvnYbFJ38qy4q5ACPs7A1wi9Dvt4btqvJEASN JRcAfFNl/Rus7sCZesnTcXtAA19UWpH9SdSGiQl1NJvMJT7U+LuT1BaS2a/PFa5px4kx pXpbwgbC6gkmP8DyI2jV3u8d/ScBET/qwuIYs3XjuIo1j/YU4/kQ2yJX4qOXbs/N0G6N 2IRmuwHeTu0Qb1qsyRUHl6+ntCak5prXOtz2tRpDsB0wqlM+OEOd1xqLugms8obetB0E s9tA== X-Forwarded-Encrypted: i=1; AJvYcCU138DAlDN78pI7Aj2NEwXgveSGvYkqY4nLt1qs1Z03kbx6WzspTmV45iIz2qdMATgZvdyo2qSXYg==@kvack.org X-Gm-Message-State: AOJu0Yzh6Nj3dGHQ279CV6I2jJLRzUoZThbvIWT8kbDG6eTfV05KDy8J 9DcrkWP9hKhbeWrlHLVPj7UO6cwh75BQi4AmS/XaFJWb+1xWipC9vJjTFiBtwQs= X-Google-Smtp-Source: AGHT+IGRgwQMcdUN+DdM+bHtNlDSqsON7etEGgvrap7Zi8+M8ABi3eEaKwZlzaeZthvdRl0aSSBn8w== X-Received: by 2002:a17:90a:4b88:b0:2e2:d197:40f3 with SMTP id 98e67ed59e1d1-2e56172465amr1204446a91.35.1729218226505; Thu, 17 Oct 2024 19:23:46 -0700 (PDT) Received: from [10.84.149.95] ([63.216.146.178]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-2e55da3bc3fsm651646a91.42.2024.10.17.19.23.38 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 17 Oct 2024 19:23:44 -0700 (PDT) Message-ID: <5242273a-e5c8-44f3-93ba-488e64af78c3@bytedance.com> Date: Fri, 18 Oct 2024 10:23:35 +0800 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v1 2/7] mm: make zap_pte_range() handle full within-PMD range Content-Language: en-US To: Jann Horn Cc: david@redhat.com, hughd@google.com, willy@infradead.org, mgorman@suse.de, muchun.song@linux.dev, vbabka@kernel.org, akpm@linux-foundation.org, zokeefe@google.com, rientjes@google.com, peterx@redhat.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, x86@kernel.org References: From: Qi Zheng In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Stat-Signature: 181iodzc4x3a86wb39pz8zjhcy4zgsgn X-Rspamd-Queue-Id: DC8DD40012 X-Rspam-User: X-Rspamd-Server: rspam10 X-HE-Tag: 1729218222-942910 X-HE-Meta: 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 jEE4bjHE AGkIEfIj/kOsb8XsNoVoYCZf/cWQZNnRojqK+bI1unmI1194FY7b7Z2kDEnXrHEcciUjrrffzWKYdg2SN33rM188KX7Ui+91PjwY9LdCoVGp84MeJecmb38OPJjJeZGCa1srpVwrfSXI6vhOGHF/c5h7VtLHiQZCCkTeiVZKkAQPNgXUUgyDN93chP/N7jZopzFR7XlK45zdTI6/a51TUGdxO9z7227+mIiZxTiVJ20346Gx1mNrELGCEbh1hfKnL0k8V1N3hEttAP/t7yY6Hq/ny1FmohJKAw9nmQ0aaMC4QgX9UiwWXJKmGnOqMVJBM5wrL0Hh37MSminlnUcuNKS76HqQM97prpBTtVyXOW17ranaDKwNNYVu7txpAZ0pckqVKCf+LnkklOVsNMo7oGaURpaVh7NsRysZRJK3t4xjBPqs4BAF6vyJlAQ== 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 2024/10/18 02:06, Jann Horn wrote: > On Thu, Oct 17, 2024 at 11:48 AM Qi Zheng wrote: >> In preparation for reclaiming empty PTE pages, this commit first makes >> zap_pte_range() to handle the full within-PMD range, so that we can more >> easily detect and free PTE pages in this function in subsequent commits. > > I think your patch causes some unintended difference in behavior: > >> Signed-off-by: Qi Zheng >> --- >> mm/memory.c | 8 ++++++-- >> 1 file changed, 6 insertions(+), 2 deletions(-) >> >> diff --git a/mm/memory.c b/mm/memory.c >> index caa6ed0a7fe5b..fd57c0f49fce2 100644 >> --- a/mm/memory.c >> +++ b/mm/memory.c >> @@ -1602,6 +1602,7 @@ static unsigned long zap_pte_range(struct mmu_gather *tlb, >> swp_entry_t entry; >> int nr; >> >> +retry: > > This "retry" label is below the line "bool force_flush = false, > force_break = false;", so I think after force_break is set once and > you go through the retry path, every subsequent present PTE will again > bail out and retry. I think that doesn't lead to anything bad, but it > seems unintended. Right, thanks for catching this! Will set force_flush and force_break to false under "retry" label in v2. Thanks!