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Fri, 10 Mar 2023 15:42:31 -0800 (PST) MIME-Version: 1.0 References: <20230209031159.2337445-1-ouyangweizhao@zeku.com> <93b94f59016145adbb1e01311a1103f8@zeku.com> <2b57491a9fab4ce9a643bd0922e03e73@zeku.com> In-Reply-To: From: Andrey Konovalov Date: Sat, 11 Mar 2023 00:42:20 +0100 Message-ID: Subject: Re: [PATCH v2] kasan: fix deadlock in start_report() To: Catalin Marinas , Peter Collingbourne Cc: =?UTF-8?B?6KKB5biFKFNodWFpIFl1YW4p?= , Dmitry Vyukov , =?UTF-8?B?5qyn6Ziz54Kc6ZKKKFdlaXpoYW8gT3V5YW5nKQ==?= , Andrey Ryabinin , Alexander Potapenko , Vincenzo Frascino , Andrew Morton , "kasan-dev@googlegroups.com" , "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" , Weizhao Ouyang , =?UTF-8?B?5Lu756uL6bmPKFBlbmcgUmVuKQ==?= Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspam-User: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 78017180017 X-Stat-Signature: c46xhxueuodpwcdg9ew448yc1ec7cxy8 X-HE-Tag: 1678491752-541683 X-HE-Meta: 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 9RAdwOHD 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 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: On Wed, Mar 1, 2023 at 6:00=E2=80=AFPM Catalin Marinas wrote: > > Yes. I'm including Vincenzo's patch below (part of fixing some potential > strscpy() faults with its unaligned accesses eager reading; we'll get to > posting that eventually). You can add some arch_kasan_enable/disable() > macros on top and feel free to include the patch below. Ah, perfect! I'll send a patchset soon. Thanks! > Now, I wonder whether we should link those into kasan_disable_current(). > These functions only deal with the depth for KASAN_SW_TAGS but it would > make sense for KASAN_HW_TAGS to enable tag-check-override so that we > don't need to bother with a match-all tags on pointer dereferencing. Using these TCO routines requires having (at least) migration disabled, rig= ht? It's not a problem for KASAN reporting code, as it already disables preemption anyway. The question is with the other kasan_disable/enable_current() call sites. But as within all of them, the code does either a single access or a memcpy or something similar, I think we can disable preemption for that duration. On a related note, I recalled that we also have a bug about using supporting no_sanitize_address for HW_TAGS KASAN. And Peter suggested using TCO entry/exit instrumentation to resolve it [2]. However, we will also need to disable preemption for the duration of no_sanitize_address-annotated functions, and I'm not sure if it's a good idea to do that via compiler instrumentation. Any thoughts? In the mean time, I'll send a simpler patchset without converting all kasan_disable/enable_current(). [1] https://bugzilla.kernel.org/show_bug.cgi?id=3D212513 [2] https://bugzilla.kernel.org/show_bug.cgi?id=3D212513#c2