Hi Marco,
On 21.04.2021 10:11, Marco Elver wrote:
On Wed, 21 Apr 2021 at 09:35, Marek Szyprowski m.szyprowski@samsung.com wrote:
On 21.04.2021 08:21, Marek Szyprowski wrote:
On 21.04.2021 00:42, Marco Elver wrote:
On Tue, 20 Apr 2021 at 23:26, Marek Szyprowski m.szyprowski@samsung.com 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 geert@linux-m68k.org # m68k Acked-by: Arnd Bergmann arnd@arndb.de # asm-generic Signed-off-by: Marco Elver elver@google.com
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.
This was a premature conclusion. It looks that during the test I've did while writing that reply, the modules were not deployed properly and a test board (RPi4) booted without modules. In that case the board booted fine and there was no udev timeout. After deploying kernel modules, the udev timeout is back.
I'm confused now. Can you confirm that the problem is due to your kernel modules, or do you think it's still due to 97ba62b27867? Or fb6cc127e0b6 (this patch)?
I don't use any custom kernel modules. I just deploy all modules that are being built from the given kernel defconfig (arm multi_v7_defconfig or arm64 default) and they are automatically loaded during the boot by udev. I've checked again and bisect was right. The kernel built from fb6cc127e0b6 suffers from the described issue, while the one build from the previous commit (2e498d0a74e5) works fine.
Best regards