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Wed, 06 Aug 2025 00:17:11 -0700 (PDT) MIME-Version: 1.0 References: <20250805062333.121553-1-bhe@redhat.com> In-Reply-To: <20250805062333.121553-1-bhe@redhat.com> From: Marco Elver Date: Wed, 6 Aug 2025 09:16:34 +0200 X-Gm-Features: Ac12FXwlK-cs-vH-SavIGCKnyqqqvtGaUUbmDgA0yfosyX6KUMYZkchuphMeuWE Message-ID: Subject: Re: [PATCH 0/4] mm/kasan: make kasan=on|off work for all three modes To: Baoquan He Cc: linux-mm@kvack.org, ryabinin.a.a@gmail.com, glider@google.com, andreyknvl@gmail.com, dvyukov@google.com, vincenzo.frascino@arm.com, akpm@linux-foundation.org, kasan-dev@googlegroups.com, linux-kernel@vger.kernel.org, kexec@lists.infradead.org Content-Type: text/plain; charset="UTF-8" X-Rspamd-Queue-Id: CA45240005 X-Stat-Signature: mb4ka5qhrh4pjzf4yyztarij1ag5g6f8 X-Rspam-User: X-Rspamd-Server: rspam11 X-HE-Tag: 1754464632-283940 X-HE-Meta: U2FsdGVkX1+yWJHvZmQrM5QNDhB21wez8wpQzFnZxK98CZV3AypUl5/CzpQm+wXskD/7vebrQNpTrO/wsAPOc73flO5/as0cMVLPaIwSqeNCUaT7D7syxVY56uScnkfxL/4Ki1fGxErqM0TIYJoqAwfGq8ZFVmDD+6iIO1TkZfF/a1b78tT2CMKRCvPrUTDT2louuliuet4uWS5NL4PVupf3qqNqeUKThAdb7DfJSevtny9Cyof8tR472V7OXCfJuucUv1F8fyWzmPIpuHaRVpAPTfaiiMuDT3p99vvo+NefjTYAqYAYwSwXOom07FTfepDMKn7hOOyQRcVH5Tx0QsGDOCVLMxmQIiW9aOXW9Zk6bR3yA5c2fNMNZUf2hDln6KsUIe2s3EsP36hNXV2emaq9HZnW45+smh7+NDtVSGSw6Kop9sFaw3Yixqa3mrvwJBO3JZ5fQxz79IhCsVtWGGE3EaCUOij6NMdlT4X4VYdBW48BVl5MsBw1hxir2Pn6PrNa8uM6i/h0pso53cMgt/1rXV57kz+KZI8493FiHWNnmzBfSm0fsOHIbA+ZKwwbNG5+Xtb0K/bciv2bhJ2XMh/y1093sNZHX0kwsBtgAj+HuKx796NQQnWvJFdZcqgB2UgORQPpL3l8g0JGDxk7+D3Vvyfs1AWigekS7tDyU+OHWqagJYgDS9QVRB7kqg1vChJvJ6A7N55Y+KcVa6bAGilcUB5idgJd3TO+FD9FEwMDF/IOvkjVhn7Z5Orr8kQlm0OI46GBaWxu4DEcc8K+5XH8JNy5H8TI+sA9wMrV7M5a4LRDWYTX/5lG1iRJxSYG1BHEQ0rUVxVWo9eJ3kBC5PbJIaTsJ98BB8klT4Fbz34D+GXMdj4TZ0L5PTqgVN+yPq6xZDahtsupmxm9DuugNOq7RrrrsMcDjO5+DJUlKkRpK9AnRd5GawzVJyr1C9KZHXZxZ5B3cyxTMh2z2bZ KT8g7SHl abT7vV6cFz8QMvC0lTK2ZElLmPC8wMd8zZ65ARUlkui9eJvMR9KteGNbQwi3fKfinrC4aYUk8Te1QUrwXDhOPtjkdYb0WriGJ8JWZllXjdeJcn+qYtWR+nLxqokE6dFSGyqDeyRp0psX3fJh5OrT5zMawWJ8W0S37GjS854cbmlAN5Q+m3O/6bUj8dSfOEJO6jv0GRtUUUXVyb2RzOvHar3RquFtS+dF79m8bYRMg/vvE5OezwhDyz6N64pXsJg4qlxH0ZgcOzNOEfZ2xSzunSVu6D+Uhr7P0br+h0vh5C/1AohbLzbDBP8YEnbMVJRhE+paqKQVFvUqMiJD0cwvb8oBnVlulRjV7q/No9vjKCVEVcsm+49FnSVEn9Q== 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 Tue, 5 Aug 2025 at 08:23, 'Baoquan He' via kasan-dev wrote: > > Currently only hw_tags mode of kasan can be enabled or disabled with > kernel parameter kasan=on|off for built kernel. For kasan generic and > sw_tags mode, there's no way to disable them once kernel is built. > This is not convenient sometime, e.g in system kdump is configured. > When the 1st kernel has KASAN enabled and crash triggered to switch to > kdump kernel, the generic or sw_tags mode will cost much extra memory > for kasan shadow while in fact it's meaningless to have kasan in kdump > kernel. Are you using KASAN generic or SW-tags is production? If in a test environment, is the overhead of the kdump kernel really unacceptable? > So this patchset moves the kasan=on|off out of hw_tags scope and into > common code to make it visible in generic and sw_tags mode too. Then we > can add kasan=off in kdump kernel to reduce the unneeded meomry cost for > kasan. > > Test: > ===== > I only took test on x86_64 for generic mode, and on arm64 for > generic, sw_tags and hw_tags mode. All of them works well. Does it also work for CONFIG_KASAN_INLINE? > However when I tested sw_tags on a HPE apollo arm64 machine, it always > breaks kernel with a KASAN bug. Even w/o this patchset applied, the bug > can always be seen too. > > "BUG: KASAN: invalid-access in pcpu_alloc_noprof+0x42c/0x9a8" > > I haven't got root cause of the bug, will report the bug later in > another thread. > ==== > > Baoquan He (4): > mm/kasan: add conditional checks in functions to return directly if > kasan is disabled > mm/kasan: move kasan= code to common place > mm/kasan: don't initialize kasan if it's disabled > mm/kasan: make kasan=on|off take effect for all three modes > > arch/arm/mm/kasan_init.c | 6 +++++ > arch/arm64/mm/kasan_init.c | 7 ++++++ > arch/loongarch/mm/kasan_init.c | 5 ++++ > arch/powerpc/mm/kasan/init_32.c | 8 +++++- > arch/powerpc/mm/kasan/init_book3e_64.c | 6 +++++ > arch/powerpc/mm/kasan/init_book3s_64.c | 6 +++++ > arch/riscv/mm/kasan_init.c | 6 +++++ > arch/um/kernel/mem.c | 6 +++++ > arch/x86/mm/kasan_init_64.c | 6 +++++ > arch/xtensa/mm/kasan_init.c | 6 +++++ > include/linux/kasan-enabled.h | 11 ++------ > mm/kasan/common.c | 27 ++++++++++++++++++++ > mm/kasan/generic.c | 20 +++++++++++++-- > mm/kasan/hw_tags.c | 35 ++------------------------ > mm/kasan/init.c | 6 +++++ > mm/kasan/quarantine.c | 3 +++ > mm/kasan/shadow.c | 23 ++++++++++++++++- > mm/kasan/sw_tags.c | 9 +++++++ > 18 files changed, 150 insertions(+), 46 deletions(-) > > -- > 2.41.0 > > -- > You received this message because you are subscribed to the Google Groups "kasan-dev" group. > To unsubscribe from this group and stop receiving emails from it, send an email to kasan-dev+unsubscribe@googlegroups.com. > To view this discussion visit https://groups.google.com/d/msgid/kasan-dev/20250805062333.121553-1-bhe%40redhat.com.