Re: [PATCH v2 1/2] seqlock: Do the lockdep annotation before locking in do_write_seqcount_begin_nested()

Michal Hocko
2023-07-31T14:25:22Z

On Sat 29-07-23 20:05:43, Tetsuo Handa wrote:
> On 2023/07/29 14:31, Tetsuo Handa wrote:
> > On 2023/07/28 0:10, Sebastian Andrzej Siewior wrote:
> >> On 2023-06-28 21:14:16 [+0900], Tetsuo Handa wrote:
> >>>> Anyway, please do not do this change only because of printk().
> >>>> IMHO, the current ordering is more logical and the printk() problem
> >>>> should be solved another way.
> >>>
> >>> Then, since [PATCH 1/2] cannot be applied, [PATCH 2/2] is automatically
> >>> rejected.
> >>
> >> My understanding is that this patch gets applied and your objection will
> >> be noted.
> >
> > My preference is that zonelist_update_seq is not checked by !__GFP_DIRECT_RECLAIM
> > allocations, which is a low-hanging fruit towards GFP_LOCKLESS mentioned at
> > https://lkml.kernel.org/r/ZG3+l4qcCWTPtSMD@dhcp22.suse.cz and
> > https://lkml.kernel.org/r/ZJWWpGZMJIADQvRS@dhcp22.suse.cz .
> >
> > Maybe we can defer checking zonelist_update_seq till retry check like below,
> > for this is really an infrequent event.
> >
>
> An updated version with comments added.

Seriously, don't you see how hairy all this is? And for what? Nitpicking
something that doesn't seem to be a real problem in the first place?
--
Michal Hocko
SUSE Labs