Hi Eric,
On Fri, 16 Apr 2021 at 23:27, Jakub Kicinski kuba@kernel.org wrote:
On Thu, 15 Apr 2021 10:37:53 -0700 Eric Dumazet wrote:
From: Eric Dumazet edumazet@google.com
Calling two copy_to_user() for very small regions has very high overhead.
Switch to inlined unsafe_put_user() to save one stac/clac sequence, and avoid copy_to_user().
Signed-off-by: Eric Dumazet edumazet@google.com Cc: Soheil Hassas Yeganeh soheil@google.com
Hi Eric!
This appears to break boot on my systems.
I have been noticing this problem.
IDK how exactly, looks like systemd gets stuck waiting for nondescript services to start in initramfs. I have lots of debug enabled and didn't spot anything of note in kernel logs.
We (LKFT) are still seeing this problem only on arm architecture on next-20210416 tag onwards. our bisect script points to this commit.
Steps to reproduce: - build linux next latest next-20210423 tag with below config - kernel-config: https://builds.tuxbuild.com/1reqrnNLnHEX9uEZFngRfaoJa9E/config - boot qemu-arm with below command - /usr/bin/qemu-system-aarch64 -cpu host,aarch64=off -machine virt-2.10,accel=kvm -nographic -net nic,model=virtio,macaddr=BA:DD:AD:CC:09:04 -net tap -m 2048 -monitor none -kernel zImage --append "console=ttyAMA0 root=/dev/vda rw" -hda rpb-console-image-lkft-am57xx-evm-20201022181203-3085.rootfs.ext4 -m 4096 -smp 2 -nographic
- After the mount rootfs - the systemd gets stuck
I'll try to poke at this more, but LMK if you have any ideas. The commit looks "obviously correct" :S
May I request to investigate this on arm architecture. The qemu_arm boot failed link, https://lkft.validation.linaro.org/scheduler/job/2565371#L540
The qemu_arm boot pass after the reverting this patch, commit 38ebcf5096a86762b82262e96b2c8b170fe79040 scm: optimize put_cmsg()
on the latest linux next tags i have to revert two commits. "scm: fix a typo in put_cmsg()" "scm: optimize put_cmsg()"
Reported-by: Naresh Kamboju naresh.kamboju@linaro.org
-- Linaro LKFT https://lkft.linaro.org
On Sun, Apr 25, 2021 at 9:59 PM Naresh Kamboju naresh.kamboju@linaro.org wrote:
Hi Eric,
On Fri, 16 Apr 2021 at 23:27, Jakub Kicinski kuba@kernel.org wrote:
On Thu, 15 Apr 2021 10:37:53 -0700 Eric Dumazet wrote:
From: Eric Dumazet edumazet@google.com
Calling two copy_to_user() for very small regions has very high overhead.
Switch to inlined unsafe_put_user() to save one stac/clac sequence, and avoid copy_to_user().
Signed-off-by: Eric Dumazet edumazet@google.com Cc: Soheil Hassas Yeganeh soheil@google.com
Hi Eric!
This appears to break boot on my systems.
I have been noticing this problem.
IDK how exactly, looks like systemd gets stuck waiting for nondescript services to start in initramfs. I have lots of debug enabled and didn't spot anything of note in kernel logs.
We (LKFT) are still seeing this problem only on arm architecture on next-20210416 tag onwards. our bisect script points to this commit.
Steps to reproduce:
- build linux next latest next-20210423 tag with below config
- kernel-config:
https://builds.tuxbuild.com/1reqrnNLnHEX9uEZFngRfaoJa9E/config
- boot qemu-arm with below command
- /usr/bin/qemu-system-aarch64 -cpu host,aarch64=off -machine
virt-2.10,accel=kvm -nographic -net nic,model=virtio,macaddr=BA:DD:AD:CC:09:04 -net tap -m 2048 -monitor none -kernel zImage --append "console=ttyAMA0 root=/dev/vda rw" -hda rpb-console-image-lkft-am57xx-evm-20201022181203-3085.rootfs.ext4 -m 4096 -smp 2 -nographic
- After the mount rootfs - the systemd gets stuck
I'll try to poke at this more, but LMK if you have any ideas. The commit looks "obviously correct" :S
May I request to investigate this on arm architecture. The qemu_arm boot failed link, https://lkft.validation.linaro.org/scheduler/job/2565371#L540
The qemu_arm boot pass after the reverting this patch, commit 38ebcf5096a86762b82262e96b2c8b170fe79040 scm: optimize put_cmsg()
Well, as already reported, this patch had an obvious typo.
Fixed later by "scm: fix a typo in put_cmsg()"
Can you trace put_cmsg() and check that systemd passes an aligned control buffer ?
Kernel was indeed able to handle arbitrary alignment, but why the application would force slow copyout() (alignment mismatch between source/destination buffers) is quite strange.
on the latest linux next tags i have to revert two commits. "scm: fix a typo in put_cmsg()" "scm: optimize put_cmsg()"
Reported-by: Naresh Kamboju naresh.kamboju@linaro.org
-- Linaro LKFT https://lkft.linaro.org
-
Eric Dumazet -
Naresh Kamboju