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Wed, 02 Jul 2025 08:47:40 -0700 (PDT) Message-ID: <4599f645-f79c-4cce-b686-494428bb9e2a@gmail.com> Date: Wed, 2 Jul 2025 17:46:23 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] kasan: don't call find_vm_area() in in_interrupt() for possible deadlock To: Yeoreum Yun , glider@google.com, andreyknvl@gmail.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 Cc: kasan-dev@googlegroups.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-rt-devel@lists.linux.dev, nd@arm.com, Yunseong Kim References: <20250701203545.216719-1-yeoreum.yun@arm.com> Content-Language: en-US From: Andrey Ryabinin In-Reply-To: <20250701203545.216719-1-yeoreum.yun@arm.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Stat-Signature: 4cwgpd194apxzypyithw5cd4k7urq15m X-Rspamd-Queue-Id: 9FC8840002 X-Rspam-User: X-Rspamd-Server: rspam07 X-HE-Tag: 1751471262-640033 X-HE-Meta: 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 I1JQgKZd QUtWgA0l3IjvkG0dxQXNI2jFPMhnBKEY4H5OFWgw8/HZyp4Bs16LNFjgi6Bi0NxO6rYYuyO6VDgEkamW8TSzSw4D1S9fGJklMeVmtLPPd3GtuQ1xWsOIkmeMmvPHs/bR2eqlyNwxSH22PRimR09YwqXRKSONWQeg8z6650JAq4d5aQTeemGARVJTiSy5Uk9lEsJMcTVCZbNKtMzYrJ9HncXfQV/Bwluq5z7oJZETfWPb21P+StouO+8JDKVxQRtZyRdMwgnCkcZskaqks1HSIxIrxR2pRAcGQ1D5vbh5UUPsFRlVNl+heiptjnNmmcMaXtK8OVrqUoVwthSfAa57Q1CBHUEWs8PfsyS/32DFEcj/7CR5qXX56xfo9MzgFrBgo85GSeR42KA/iiAJSwrzEQj4LheVbL3XFd734uDXgUVjBx/3HxeIH6EZ+i/xBP2RgbRbJadvb22Fb/oyTm9BnD9Dd4sJk9aLdKYvV5Wdzcbo5bx9Etfmgi/SaaglC7mapRPLMhM3+TnuhjROiN/GqF1PP6CeBPpQAx4YFX9R93AqQ8HoPhld+JTKfkZUEPyykvA6MhT0HSz00YVR1ZFeB8rKQDGHPSYh+dSbsqOpIa5SfolxXJTHahpnXzg7otumcHK3LEvB9lNatpEH5QIwiW1nlhe9cUf0C5g/CZrN/pD2rLYD7a4A71PgtJ6o0pJOyEs5JebBwNikcuoZaNULODGl7isRJouIwklwuUtXIXtYGA1g= 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 7/1/25 10:35 PM, Yeoreum Yun wrote: FYI some of email addresses in CC look corrupted, e.g. "kpm@linux-foundation.org", "nd@arm.com" > In below senario, kasan causes deadlock while reporting vm area informaion: > > 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! > ... > diff --git a/mm/kasan/report.c b/mm/kasan/report.c > index 8357e1a33699..61c590e8005e 100644 > --- a/mm/kasan/report.c > +++ b/mm/kasan/report.c > @@ -387,7 +387,7 @@ static inline struct vm_struct *kasan_find_vm_area(void *addr) > static DEFINE_WAIT_OVERRIDE_MAP(vmalloc_map, LD_WAIT_SLEEP); > struct vm_struct *va; > > - if (IS_ENABLED(CONFIG_PREEMPT_RT)) > + if (IS_ENABLED(CONFIG_PREEMPT_RT) || in_interrupt()) in_interrupt() returns true if BH disabled, so this indeed should avoid the deadlock. However, it seems we have similar problem with 'spin_lock_irq[save](&some_lock)' case and in_interrupt() check doesn't fix it. And adding irqs_disabled() check wouldn't make sense because print_report() always runs with irqs disabled. I see no obvious way to fix this rather than remove find_vm_area() call completely and just print less info.