On 2025-02-19 09:24:37 [+0000], MOESSBAUER, Felix wrote:
> On Fri, 2024-10-04 at 09:39 +0200, Sebastian Andrzej Siewior wrote:
> > On 2024-09-27 15:01:00 [-0400], Joseph Salisbury wrote:
> > > Is it needed in all stable release patch sets, including v5.15?
> >
> > Yes. I would appreciate backporting it all the way where the code is
> > available. The dependencies
> > 1eacdd71b3436 ("netfilter: nft_counter: Disable BH in
> > nft_counter_offload_stats().")
> > a0b39e2dc7017 ("netfilter: nft_counter: Synchronize
> > nft_counter_reset() against reader.")
> >
> > were already routed via stable.
> > The problem is that the seqcount has no lock associated so a reader
> > could preempt a writer and then lockup spinning.
>
> Hi,
>
> this needs to be backported to all stable RT trees (just checked 4.19
> and 6.1. 5.15 already has it). We observed the reader live-lock issue
> in "nft_counter_fetch" on 6.1.120-rt47 (leading to a system stall) and
> were also able to find it with lockdep (see stacktrace below).
>
> I'm wondering if this patch could be applied to linux-stable, even if
> it is just a performance optimization on non-rt kernels (not a fix).
>
> The patch "netfilter: nft_counter: Use u64_stats_t for statistic"
> cleanly applies on 6.1.y and 6.1.127-rt48.
I assumed the backport did already happen. So at least 4.19 and 6.1 is
missing you say.
4.19 will remain at missing it because it is EOL.
6.1 would be Clark's department.
Could everyone please report what the status on backporting is?
If you want to pull the performance card and route it via the stable
tree, I suggest to ask the netfilter people if they object. And then it
might work.
Sebastian
