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 E6B10C83F1D for ; Sun, 13 Jul 2025 23:27:52 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 846EE6B0092; Sun, 13 Jul 2025 19:27:52 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 81E056B0093; Sun, 13 Jul 2025 19:27:52 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 734686B0095; Sun, 13 Jul 2025 19:27:52 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) by kanga.kvack.org (Postfix) with ESMTP id 620F46B0092 for ; Sun, 13 Jul 2025 19:27:52 -0400 (EDT) Received: from smtpin13.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay06.hostedemail.com (Postfix) with ESMTP id 2245310E321 for ; 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t=1752449270; 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: in-reply-to:in-reply-to:references:references; bh=1xw1ouskdusNRcbgp4uxp4FwvsFlVFNyTSL6KjlcnAI=; b=Mn+BusYqoFZ6mmBrbPihE93qKq6N0oxpvEmfpPBBVAIbdrOVD5QwjSE8/WccRJkWTmIXj7 sC58d5v8rPrpUHqIp7/uyxmDumoxiL6XF9UydExrBbHwbZKk1VEfkAfzACsmg+fJ98UTy+ ylew3/wfnGlGpuTMiIWqCRV2vPbrUVU= X-AuditID: a67dfc5b-669ff7000002311f-54-687440f1ab53 Date: Mon, 14 Jul 2025 08:27:40 +0900 From: Byungchul Park To: Yeo Reum Yun Cc: Andrey Konovalov , "akpm@linux-foundation.org" , "glider@google.com" , "dvyukov@google.com" , Vincenzo Frascino , "bigeasy@linutronix.de" , "clrkwllms@kernel.org" , "rostedt@goodmis.org" , "max.byungchul.park@gmail.com" , "ysk@kzalloc.com" , "kasan-dev@googlegroups.com" , "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" , "linux-rt-devel@lists.linux.dev" , "kernel_team@skhynix.com" , "urezki@gmail.com" Subject: Re: [PATCH v2] kasan: remove kasan_find_vm_area() to prevent possible deadlock Message-ID: <20250713232740.GA18327@system.software.com> References: <20250703181018.580833-1-yeoreum.yun@arm.com> <20250711020858.GA78977@system.software.com> <20250711021100.GA4320@system.software.com> MIME-Version: 1.0 Content-Type: text/plain; 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The > > time complextity looks O(log N). I don't think an irq disabled section > > of O(log N) is harmful. I still think using > > spin_lock_irqsave(&vn->busy.lock) can resolve this issue with no worry > > of significant irq delay. Am I missing something? > > I don't agree for this. > since in PREEMPT_RT case, it has the same problem. > > In case of PREEMPT_RT, spin_lock_irqsave() becomes rt_spin_lock() which is sleepable. > But, KASAN calls "rt_spin_lock()" holding raw_spin_lock_irqsave() which is definitely wrong. It's another issue than irq handling latency, but it's about lock usage correctness. You are right. Byungchul > But as Uladzislau said, without reference count manage, UAF can always happen. > IOW, If KASAN to dump vm information, I think we need: > 1. manage reference for vmap_area. > 2. find_vm_area() with rcu version. > > > Thanks. > > -- > Sincerely, > Yeoreum Yun