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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 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-Originating-IP: [10.174.179.234] X-ClientProxiedBy: dggems705-chm.china.huawei.com (10.3.19.182) To kwepemk500005.china.huawei.com (7.202.194.90) X-Rspam-User: X-Rspamd-Queue-Id: 6E4081C0007 X-Stat-Signature: 91neiibqjwatgyqp5g9r49b9n4njh6pf X-Rspamd-Server: rspam03 X-HE-Tag: 1739847239-850549 X-HE-Meta: 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 xiEhnnAz HeJMHvQG6OUcMsUR0fx+aQjpyDBrzyYUeXm0vXfx/L0NmfYZHZPP5lp6FR+oR86Js814p4g4wig0SQMGBMViZP5dQDOH756UiXcFsK8ttNItrXsrJzKwFffkFQTFck9DXfrcR4x/8NEibzaCqUw0L5WAYWIsMF3PtES7PgJdJYWXgdH1tqgbmlNvfdsST7Z4IJDcY3V8vkdPC/tHBgrRkBfWlmqNaqxPorvxi 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: 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 >> > > > .