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Tue, 9 Apr 2024 21:28:00 +0800 Message-ID: <4311bf57-ea3e-4ea6-8f7b-370d9dd2dac1@huawei.com> Date: Tue, 9 Apr 2024 21:27:59 +0800 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] mm,page_owner: Defer enablement of static branch Content-Language: en-US To: Oscar Salvador , Andrew Morton CC: , , Vlastimil Babka References: <20240409131715.13632-1-osalvador@suse.de> From: Kefeng Wang In-Reply-To: <20240409131715.13632-1-osalvador@suse.de> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [10.174.177.243] X-ClientProxiedBy: dggems706-chm.china.huawei.com (10.3.19.183) To dggpemm100001.china.huawei.com (7.185.36.93) X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: CA8E54001F X-Stat-Signature: ph5nm7646zcr57pqymnefz7siwcyaaj4 X-Rspam-User: X-HE-Tag: 1712669284-278566 X-HE-Meta: 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 9AjlPOc7 Ww00Dki9dKETh4hPBx72B50a3KQlWVVw8XVzqlI1bnSyIPrhUyls17WWvXn87HvpIPvNL4IpVMNRJhsJhbd0OJk38AwcBRg4OFnzea+/Xfrikq+wbOYClbcmu6Ko4KRW9pFRgHFoq3xeZEJXL7KEiEyi635spoOEB19Myx6x1ILClOEunUCxNxnE3IYdU0LE6Q7YIANT6e8jtXjKc2S0hMcG3yGnGLjT+KzX6BT1qpbMx48RuU7dWtj7Ch2I0z7wrN2Mcqe1sDvJQ5IRjb7shfBiq2Wap3K8EINobHs9Ll4ZiuXo= 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 2024/4/9 21:17, Oscar Salvador wrote: > Kefeng Wang reported that he was seeing some memory leaks with kmemleak > with page_owner enabled. > The reason behind is that we enable the page_owner_inited static branch > and then proceed with the linking of stack_list struct to dummy_stack, > which means that exists a race window between these two steps where we > can have pages already being allocated calling add_stack_record_to_list(), > allocating objects and linking them to stack_list, but then we set > stack_list pointing to dummy_stack in init_page_owner. > Which means that the objects that have been allocated during that time > window are unreferenced and lost. > > Fix this by deferring the enablement of the branch until we have properly > set up the list. > > Reported-by: Kefeng Wang > Closes: https://lore.kernel.org/linux-mm/74b147b0-718d-4d50-be75-d6afc801cd24@huawei.com/ > Tested-by: Kefeng Wang > Fixes: 4bedfb314bdd ("mm,page_owner: maintain own list of stack_records structs") > Signed-off-by: Oscar Salvador > --- > Special thanks and kudos go to Kefeng Wang for helping me out chasing > down this bug, as I could not reproduce it with any of my machines, and > to Vlastimil to bring another pair of eyes, which was very helpful. > The issue is found by accident when test my migrate changes, thanks for your great job and quick response, this does pass my test, thanks ;) > mm/page_owner.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/mm/page_owner.c b/mm/page_owner.c > index 9bef0b442863..742f432e5bf0 100644 > --- a/mm/page_owner.c > +++ b/mm/page_owner.c > @@ -118,7 +118,6 @@ static __init void init_page_owner(void) > register_dummy_stack(); > register_failure_stack(); > register_early_stack(); > - static_branch_enable(&page_owner_inited); > init_early_allocated_pages(); > /* Initialize dummy and failure stacks and link them to stack_list */ > dummy_stack.stack_record = __stack_depot_get_stack_record(dummy_handle); > @@ -129,6 +128,7 @@ static __init void init_page_owner(void) > refcount_set(&failure_stack.stack_record->count, 1); > dummy_stack.next = &failure_stack; > stack_list = &dummy_stack; > + static_branch_enable(&page_owner_inited); > } > > struct page_ext_operations page_owner_ops = {