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Thu, 03 Jul 2025 12:05:31 -0700 (PDT) MIME-Version: 1.0 References: <20250703181018.580833-1-yeoreum.yun@arm.com> In-Reply-To: From: Andrey Konovalov Date: Thu, 3 Jul 2025 21:05:20 +0200 X-Gm-Features: Ac12FXyxUbHA_lo-Kj6ls_i2v0Skaq2nx5J2PN_n_cVaHRgGx5xPMKN_AxPcMMo Message-ID: Subject: Re: [PATCH v2] kasan: remove kasan_find_vm_area() to prevent possible deadlock To: Yeoreum Yun Cc: glider@google.com, dvyukov@google.com, vincenzo.frascino@arm.com, akpm@linux-foundation.org, bigeasy@linutronix.de, clrkwllms@kernel.org, rostedt@goodmis.org, byungchul@sk.com, 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, Andrey Ryabinin Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspam-User: X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: A45B1100012 X-Stat-Signature: bb7tmpukicnk158goti1e1e1e653a8rc X-HE-Tag: 1751569534-120823 X-HE-Meta: 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 6cIjAMDb BoZDjXgjYnckB9RZw+VKVPivKZ80MjhOaktOyY6RXUw+2a72rj7oHrAE6O5NAxT8iFguYY3D+hCdMqRp0yDWgddh9ktcRy8eZQqtRezY5yOPEPGwodF3ARTnSiQDCeno6X2niB4xVe4/QMTanbJrnwkdcdAqxX6t6EGfv+AQeupaai91LcxURGlwErjyc/At6lRqVQFqKp2G0Q7UtJ/s5EzqqZBzRvJegpL+AwyI5zIv6Y4O+9iHrnGAjsoYvCtrTsbAsF5uhnGR0u2smmoTts+5V/VCLByYCpuwLYXFK+SOjhmuquLnxfb4JwEUqQLT6DozWcw6K1aeg/UmWTYHicZ6cPULJpN6FcCt6l+5fui8IRgLMIQqVX5wWJLRydhmV/Z499b8mPSvJwqJlEHyHEwY0ktpcslOGNAizF9gy7NIS2UmAXKJAFafXgU0qb0pVdfefe8ZMDeO6oOFHRtrRL9l5K5kncuxcWNQguDxSlF9W0zomBIpVyUZ+RXWKzPOqv7O+K3tYt51EImAlc9qWnfW7iMdYUTx3wABJ 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 Thu, Jul 3, 2025 at 8:55=E2=80=AFPM Yeoreum Yun wr= ote: > > Hi Andrey, > > > > > > > find_vm_area() couldn't be called in atomic_context. > > > If find_vm_area() is called to reports vm area information, > > > kasan can trigger deadlock like: > > > > > > CPU0 CPU1 > > > vmalloc(); > > > alloc_vmap_area(); > > > spin_lock(&vn->busy.lock) > > > spin_lock_bh(&some_lock); > > > > > > > > > spin_lock(&some_lock); > > > > > > kasan_report(); > > > print_report(); > > > print_address_description(); > > > kasan_find_vm_area(); > > > find_vm_area(); > > > spin_lock(&vn->busy.lock) //= deadlock! > > > > > > To prevent possible deadlock while kasan reports, remove kasan_find_v= m_area(). > > > > Can we keep it for when we are in_task()? > > We couldn't do. since when kasan_find_vm_area() is called, > the report_lock is grabbed with irq disabled. > > Please check discuss with Andrey Ryabinin: > https://lore.kernel.org/all/4599f645-f79c-4cce-b686-494428bb9e2a@gmail.= com/ That was about checking for !in_interrupt(), but I believe checking for in_task() is different? But I'm not an expert on these checks.