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b=R4fI54Mxj6QHsAAOAeoV190DscJoLR/x3bJ7wtanPBdnNInG3neKCqgtEyRqF68YM axmakqbVm7c5IF0+0WU9QZojQKP4GM0fwKLgakOGc/hLjg9dKO0e1AkyqvcZ4NKg/o ySiAor7Az2ll7pZCJH0BoMQqlH3aLwXLj7n87mVQ= Date: Thu, 3 Jul 2025 13:35:42 -0700 From: Andrew Morton To: Yeoreum Yun Cc: glider@google.com, andreyknvl@gmail.com, dvyukov@google.com, vincenzo.frascino@arm.com, 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 Subject: Re: [PATCH v2] kasan: remove kasan_find_vm_area() to prevent possible deadlock Message-Id: <20250703133542.b9d61290725adee655c9b491@linux-foundation.org> In-Reply-To: <20250703181018.580833-1-yeoreum.yun@arm.com> References: <20250703181018.580833-1-yeoreum.yun@arm.com> X-Mailer: Sylpheed 3.7.0 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: C815918000F X-Stat-Signature: kx74goikd76kfz39586wqqc8ke86ad65 X-Rspam-User: X-HE-Tag: 1751574944-29955 X-HE-Meta: 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 Otcmati+ hZxzJf+mxHe63hOtle/E9ruEG66lVnFObf0UzBLoQzwl5GQEPCq51YqG8QLfaA6rAKpAao8YySjZYhT4375672i62kLpXpryvLIH/GNSQiSo1pXtx7Tl/cgm63NJU2DvI3r2mnUHR5zF77CjtRx48okzoULQyJGMmkFD1aSH/PAL3+ZWE9wndr++dvrYCwsF9uYFxcczSX+0p9ftNudmK7axjtCrHiZWUHdhHoaBfgrTSKvrLtmR6vOm6i648LkhOhsiiFAyWADfFU7FmOk1Ch9xBfROxWUKkNRIHz08jyd6bQeE2/BnaMl4Afy1KXX/4N+MvqNfxSdoS+7sz7QQ6JYQ6iOohE26hafy32eWKNiWUuRtVGQ23eJ6aOoNgK7JRqUSB2W5vAMe2T1zzAPkZL5X6VxURZ5tByHGXwv8r7yBkuRHVsFHGde69hdnzDeuDRjPH018Lr9ZYoWyTMj5Ih614aSmQEahAoVyI8MOJSxhvYVxcOfNCh9AgFCMsyN0XcucZekmS52vuL9k= 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, 3 Jul 2025 19:10:18 +0100 Yeoreum Yun wrote: > 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_vm_area(). > > Fixes: c056a364e954 ("kasan: print virtual mapping info in reports") Three years. > Reported-by: Yunseong Kim > Signed-off-by: Yeoreum Yun Thanks, I'll queue this (with a cc:stable) for testing and I shall await the conclusion of the ongoing review discussion.