Fwd: mmap issue with 22.04.3 and kernel 6.2

[Mauricio Faria de Oliveira]

Hi Mathieu,

On Tue, Aug 22, 2023 at 11:20 AM Mathieu Fluhr <mathieu.fluhr at gmail.com> wrote:
>
> Hello,
>
> First of all, I apologize if this is not the right place to report a bug, but for some obscure reason, I cannot login to launchpad with my Ubuntu One account (I always end up on the "Ooops" page...).

No worries, thanks for reporting an issue in some way.
(For the login issue, see login.ubuntu.com > Support > Other > "When I
try to log in, I get an "OOPS" message. What should I do?")

If this helps, please know that in the future, you can reach out to
our kernel team specifically, kernel-team at lists.ubuntu.com [2].

>
> I am compiling (daily) the Android OS (AOSP) which makes a heavy use of hardware resources and several parts of it relies on the mmap() system call. Updating to 22.04.3 last Thursday started to trigger several (non-consistent) build errors, all related to mmap(), claiming that it can't allocate memory.... which is not consistent with the fact that my workstation still had 50GB+ free RAM at that time.
>
> Digging a bit into the issue, I found out that it was a known issue, and that the fix has been merged in the 6.1 LTS kernel [1] but unfortunately not in 6.2, since the patch appeared after the last 6.2.16 release.
>
> I applied it locally and rebuilt a new kernel, and I can confirm this fixes the issue.
> Could it be possible to think about applying it to the official 6.2 ubuntu package so that I don't have to always "downgrade" to the old 5.19 coming from 22.04.2 ?
>
> Kind Regards,
> Mathieu
>
> [1] https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/lib/maple_tree.c?h=v6.1.45&id=254ee530286aeb6d6de93d05b2247153df590af1

Looking at the patch [1] ...
"""
maple_tree: make maple state reusable after mas_empty_area()
commit 0257d9908d38c0b1669af4bb1bc4dbca1f273fe6 upstream.
"""
... and the lunar/6.2-based kernel package git repo, it should be
available in lunar-proposed.

Could you please test it?

$ git remote get-url origin
git://git.launchpad.net/~ubuntu-kernel/ubuntu/+source/linux/+git/lunar

$ git log --oneline origin/master-next -- lib/maple_tree.c | head -n1
a08052779ad6 maple_tree: make maple state reusable after mas_empty_area()

$ git show a08052779ad6 | grep 'commit .* upstream'
    commit 0257d9908d38c0b1669af4bb1bc4dbca1f273fe6 upstream.

$ git describe --contains a08052779ad6
Ubuntu-6.2.0-30.30~288

$ rmadison -a source linux | grep lunar
 linux | 6.2.0-20.20    | lunar           | source
 linux | 6.2.0-27.28    | lunar-security  | source
 linux | 6.2.0-27.28    | lunar-updates   | source
 linux | 6.2.0-32.32    | lunar-proposed  | source

$ sudo add-apt-repository -yp proposed

ubuntu at lunar:~$ apt policy linux-image-6.2.0-32-generic
...
        100 http://archive.ubuntu.com/ubuntu lunar-proposed/main amd64 Packages
        100 http://security.ubuntu.com/ubuntu lunar-proposed/main amd64 Packages

$ sudo apt install linux-image-6.2.0-32-generic
$ ... reboot

cheers,

[2] https://lists.ubuntu.com/mailman/listinfo/kernel-team

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-- 
Mauricio Faria de Oliveira