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Wed, 21 Apr 2021 06:21:18 +0000 (GMT) Subject: Re: [PATCH v4 05/10] signal: Introduce TRAP_PERF si_code and si_perf to siginfo To: Marco Elver Cc: Peter Zijlstra , Alexander Shishkin , Arnaldo Carvalho de Melo , Ingo Molnar , Jiri Olsa , Mark Rutland , Namhyung Kim , Thomas Gleixner , Alexander Potapenko , Al Viro , Arnd Bergmann , Christian Brauner , Dmitry Vyukov , Jann Horn , Jens Axboe , Matt Morehouse , Peter Collingbourne , Ian Rogers , Oleg Nesterov , kasan-dev , linux-arch , linux-fsdevel , LKML , the arch/x86 maintainers , "open list:KERNEL SELFTEST FRAMEWORK" , Geert Uytterhoeven , Bartlomiej Zolnierkiewicz From: Marek Szyprowski Message-ID: <43f8a3bf-34c5-0fc9-c335-7f92eaf23022@samsung.com> Date: Wed, 21 Apr 2021 08:21:17 +0200 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.9.1 MIME-Version: 1.0 In-Reply-To: Content-Transfer-Encoding: 7bit Content-Language: en-US X-Brightmail-Tracker: H4sIAAAAAAAAA01Se0xTZxzdd+/t7YUEvZQOvlhks07MXMCRLdsXdYRFltxNwsTMmMA2KeUG 2aCyljI1OFscXW2caBOhNDyqUyQ8BMqzhPerY0DHYwxlIAroBlnbNNRNYYxR7tj47/x+5/y+ c07yUbigjtxBJcvSWblMkiImvYmGvue2kPieC/Gvj+j3IN2DJhJpzfk8tKrv46Py6RwS1Riq eEjt2I2uPtLwkWawkYeeTLZi6BtXK45M2W4+Gu0PQb1DqxgqfTKDIW3zUwK1tPYTaKy5gER5 U04S3Z4YwdB3nR08NNphwlBWST2B6tuzAcqZmiCR9dsODNWar+Pox1UrDz2rnuNFBDIVRRWA WVnWA2a10IUzJrOSabnWTzK1pfuYsSElYy67RDIOm43PdHVrAVPUH8M428ZJ5kpdGWCWzEGM ed6OHd0e630okU1JzmDl+8PjvU81dKrwtF6/M5WmPEIFZrbrgBcF6TfhbVMvTwe8KQFdCuCt pm7gIQS0G8DZXAVHLAFYuDDH37xwj1QQHHEHQOeftzBucAHoUmt5HpUfHQu7bcO4BwtpMbTP XcE9Ipwep6DW0o15CJIOgzq7jvRgHzocZruLNrwJeg9ssqs3HnqRToD3R9dwTuML+/PnCQ/2 omNgZ1Prxjs4/RJstBfgHA6Ak/PFG4kgbfGGswYzxuWOhK3DDwkO+8FFa92/fQLhmmXz4CKA j2yVfG64DOBYlgFwqoNwyra8HpVat3gVVjXv59bvwsVqI+ZZQ3obvGf35UJsg/qGPJxb+0Ct RsCpg6HRevc/287hUfwqEBu3VDNuqWPcUsf4v68JEGUggFUqUpNYxRsy9stQhSRVoZQlhUpP p5rB+sce+Nv6tAmULrpCuwBGgS4AKVws9Jk5nxkv8EmUnD3Hyk+flCtTWEUXEFGEOMCnub7i pIBOkqSzn7NsGivfZDHKa4cKi1t5ecIR/YXvpz0PQzSxkXWfZb1VjA8NFLruBe50YaK325R/ aQOcxwfOa4ODEqJ6hJWuT7pCWnLL5g72xFRVK6THJK+tia2TZw6VGKI7DkhF9pr34oqtqo8/ DLucQdwR/qBbKB9PiX529v3d03La9IdTld77a8TPJbq1c6PPf7p/LFq6NL2cZhZoEm4aMIfp or4958ZaltcRdWLvTnfJK4lHr30V/LgKrAqdY22iE+/sqh3c6xD9cmnX4Upjvn/u7x/ETkT5 Wz7KjNx7OK+PlA1aVh6M8+tfSMo0nViJvdDoPxmhFo2og47EmR2/HahZaHk87nuDDW//XlqQ HDXLZtz8ulxMKE5JwvbhcoXkH9fSTxdHBAAA X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFjrGKsWRmVeSWpSXmKPExsVy+t/xe7oJR+oTDNrPMVt03dvBZtGxaSar xd9Jx9gtVt/tZ7PYOGM9q0XjO2WLCQ/b2C3azmxntXh2ay+TRfvHvcwWC1q/sFtcOqlrcfTs XyaLFc/uM1l07PrKYrFn70kWi8u75rBZTL/zns1i6fWLTBaLDx5gtbh0YAGTRdOyrSwWW/e3 Mlr037nOZnG89wCTxeZNU5ktzv89zmrxY8NjVgcZjzXz1jB6/P41idHj79yPzB4LNpV67Jl4 ks1j8wotj8tnSz02repk83h37hy7x6HDHYwe804Gerzfd5XNo2/LKkaPz5vkPDY9ecsUwB+l Z1OUX1qSqpCRX1xiqxRtaGGkZ2hpoWdkYqlnaGwea2VkqqRvZ5OSmpNZllqkb5egl7HtYANz wVHhirULprM0MN7n72Lk5JAQMJH4cnENC4gtJLCUUaJ3fS1EXEbi5LQGVghbWOLPtS62LkYu oJr3jBJ71r9mA0kIC0RJXPr7jhnEFhFQknj7uI8ZpIhZ4CaHxJKdT5ggOrYySWw6/4IdpIpN wFCi620XWDevgJ1E65d5jCA2i4CqxI63jWDrRAWSJO5dXskMUSMocXLmE7DzOAUCJQ7u2MsE YjMLmEnM2/yQGcKWl9j+dg6ULS5x68l8pgmMQrOQtM9C0jILScssJC0LGFlWMYqklhbnpucW G+kVJ+YWl+al6yXn525iBCaobcd+btnBuPLVR71DjEwcjIcYJTiYlUR479fWJAjxpiRWVqUW 5ccXleakFh9iNAX6ZyKzlGhyPjBF5pXEG5oZmBqamFkamFqaGSuJ85ocWRMvJJCeWJKanZpa kFoE08fEwSnVwLT3i7mHpPEKxg1z7HzZ20UcnJ8WLOVbkhZyTk7+W5hE1uwZbm/MWOJ3FbO5 rumxS7+82E+jwuF+wQQx8ckRdX82vkvtPzAz1VTRez+D4jFbW+ZlkYJmKS4LT3/Ynrsx1iff ZmXNBL3gfPEAwanN3A35l43s18r6f+PzWpVat0/4iKGHZhx3x1Zzt+JZfuEvHM5OKQ1iymIt Prn5x+KPL4y15dk0/K6vTZZ38Dn+7rbnzW9xN3ZMiVj3Zb139K0JbeeSfzClzZWQUBZ7miza HbaVJZit62qEW+KK277i4qfOCa5a9+K+/KmV+5I2Pdz0deqffeLRUkuVhFaYTDlydnKRqojZ N1/Ff6JnN531UWIpzkg01GIuKk4EAPvESsjZAwAA X-CMS-MailID: 20210421062120eucas1p2fb703eea4e1f49cad8352006e4719b08 X-Msg-Generator: CA Content-Type: text/plain; charset="utf-8" X-RootMTR: 20210420212618eucas1p102b427d1af9c682217dfe093f3eac3e8 X-EPHeader: CA CMS-TYPE: 201P X-CMS-RootMailID: 20210420212618eucas1p102b427d1af9c682217dfe093f3eac3e8 References: <20210408103605.1676875-1-elver@google.com> <20210408103605.1676875-6-elver@google.com> <1fbf3429-42e5-0959-9a5c-91de80f02b6a@samsung.com> Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org Hi, On 21.04.2021 00:42, Marco Elver wrote: > On Tue, 20 Apr 2021 at 23:26, Marek Szyprowski wrote: >> On 08.04.2021 12:36, Marco Elver wrote: >>> Introduces the TRAP_PERF si_code, and associated siginfo_t field >>> si_perf. These will be used by the perf event subsystem to send signals >>> (if requested) to the task where an event occurred. >>> >>> Acked-by: Geert Uytterhoeven # m68k >>> Acked-by: Arnd Bergmann # asm-generic >>> Signed-off-by: Marco Elver >> This patch landed in linux-next as commit fb6cc127e0b6 ("signal: >> Introduce TRAP_PERF si_code and si_perf to siginfo"). It causes >> regression on my test systems (arm 32bit and 64bit). Most systems fails >> to boot in the given time frame. I've observed that there is a timeout >> waiting for udev to populate /dev and then also during the network >> interfaces configuration. Reverting this commit, together with >> 97ba62b27867 ("perf: Add support for SIGTRAP on perf events") to let it >> compile, on top of next-20210420 fixes the issue. > Thanks, this is weird for sure and nothing in particular stands out. > > I have questions: > -- Can you please share your config? This happens with standard multi_v7_defconfig (arm) or just defconfig for arm64. > -- Also, can you share how you run this? Can it be reproduced in qemu? Nothing special. I just boot my test systems and see that they are waiting lots of time during the udev populating /dev and network interfaces configuration. I didn't try with qemu yet. > -- How did you derive this patch to be at fault? Why not just > 97ba62b27867, given you also need to revert it? Well, I've just run my boot tests with automated 'git bisect' and that was its result. It was a bit late in the evening, so I didn't analyze it further, I've just posted a report about the issue I've found. It looks that bisecting pointed to a wrong commit somehow. > If you are unsure which patch exactly it is, can you try just > reverting 97ba62b27867 and see what happens? Indeed, this is a real faulty commit. Initially I've decided to revert it to let kernel compile (it uses some symbols introduced by this commit). Reverting only it on top of linux-next 20210420 also fixes the issue. I'm sorry for the noise in this thread. I hope we will find what really causes the issue. Best regards -- Marek Szyprowski, PhD Samsung R&D Institute Poland