From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from szxga02-in.huawei.com (szxga02-in.huawei.com [45.249.212.188]) (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 3FEF514A4E0; Tue, 18 Feb 2025 02:53:57 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.249.212.188 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1739847240; cv=none; b=AWHGlUdUUK+omtlYSYcBcXktsQ1q7ESvKVGHCQbEj8p49Kk4RwOklJyl0hILQunGisJ2O27+jGu46XZWS7INtCRulPzXDJYMbNP6OCMOk6GmuXhw2LnJ4NDYIfalhzjF5j1s+WO5bliQwCabcE1MHj74aHsYjvQxwyjxhRYi16k= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1739847240; c=relaxed/simple; bh=493fq42fS56Pd9EQ89l57uN+C+1NmFHr9GOTDqiqx1g=; h=Message-ID:Date:MIME-Version:Subject:To:CC:References:From: In-Reply-To:Content-Type; b=bSUqBISD5CmqEazeSMd5g+6eo2DLQMOxqPFaOMET2u4s/+v/rmL8h6qz6PmxlAFPwfhSN2LzLoqubTSOD9JAxM3UZoWUJNqW0/2tftwKfYZYx9AB4XG7KlmJ3NT+sRzuLPzEISDyL8VUNJJFWh5iR7a3xArqGIHrzS4iUOwmBZI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com; spf=pass smtp.mailfrom=huawei.com; arc=none smtp.client-ip=45.249.212.188 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huawei.com Received: from mail.maildlp.com (unknown [172.19.88.194]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4YxkZr4BdBzcr0Y; Tue, 18 Feb 2025 10:52:20 +0800 (CST) Received: from kwepemk500005.china.huawei.com (unknown [7.202.194.90]) by mail.maildlp.com (Postfix) with ESMTPS id 3EF7E1402C1; Tue, 18 Feb 2025 10:53:54 +0800 (CST) Received: from [10.174.179.234] (10.174.179.234) by kwepemk500005.china.huawei.com (7.202.194.90) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.11; Tue, 18 Feb 2025 10:53:52 +0800 Message-ID: <7dac9afa-9778-187d-8f69-53a7e92bbe97@huawei.com> Date: Tue, 18 Feb 2025 10:53:51 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.8.0 Subject: Re: [PATCH -next] uprobes: fix two zero old_folio bugs in __replace_page() To: Oleg Nesterov , Andrew Morton , Peter Xu , David Hildenbrand CC: Masami Hiramatsu , Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Namhyung Kim , Mark Rutland , Alexander Shishkin , Jiri Olsa , Ian Rogers , Adrian Hunter , "Liang, Kan" , , , , , , linux-mm References: <20250217123826.88503-1-tongtiangen@huawei.com> <20250217161218.GD8082@redhat.com> From: Tong Tiangen In-Reply-To: <20250217161218.GD8082@redhat.com> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit X-ClientProxiedBy: dggems705-chm.china.huawei.com (10.3.19.182) To kwepemk500005.china.huawei.com (7.202.194.90) 在 2025/2/18 0:12, Oleg Nesterov 写道: > Can't comment, my understanding of mm/ is not enough these days. > > Just one question... > > On 02/17, Tong Tiangen wrote: >> >> Fixes: 7396fa818d62 ("uprobes/core: Make background page replacement logic account for rss_stat counters") >> Fixes: 2b1444983508 ("uprobes, mm, x86: Add the ability to install and remove uprobes breakpoints") > > Are you sure this logic was wrong from the very beginning? Just curious. > > Oleg. Yes, i checked the original code logic, and the put_page() didn't take zero pages into account. Add Morton,Peter and David for discussion. Thanks, Tong. > >> Signed-off-by: Tong Tiangen >> --- >> kernel/events/uprobes.c | 6 ++++-- >> 1 file changed, 4 insertions(+), 2 deletions(-) >> >> diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c >> index 46ddf3a2334d..ff5694acfa68 100644 >> --- a/kernel/events/uprobes.c >> +++ b/kernel/events/uprobes.c >> @@ -213,7 +213,8 @@ static int __replace_page(struct vm_area_struct *vma, unsigned long addr, >> dec_mm_counter(mm, MM_ANONPAGES); >> >> if (!folio_test_anon(old_folio)) { >> - dec_mm_counter(mm, mm_counter_file(old_folio)); >> + if (!is_zero_folio(old_folio)) >> + dec_mm_counter(mm, mm_counter_file(old_folio)); >> inc_mm_counter(mm, MM_ANONPAGES); >> } >> >> @@ -227,7 +228,8 @@ static int __replace_page(struct vm_area_struct *vma, unsigned long addr, >> if (!folio_mapped(old_folio)) >> folio_free_swap(old_folio); >> page_vma_mapped_walk_done(&pvmw); >> - folio_put(old_folio); >> + if (!is_zero_folio(old_folio)) >> + folio_put(old_folio); >> >> err = 0; >> unlock: >> -- >> 2.25.1 >> > > > .