On Fri, 31 Dec 2021, Thorsten Leemhuis wrote: > On 30.12.21 00:45, Andrew Morton wrote: > > On Tue, 28 Dec 2021 11:04:18 +0100 Thorsten Leemhuis <regressions@xxxxxxxxxxxxx> wrote: > > > >> Hi, this is your Linux kernel regression tracker speaking. > >> > >> On 02.12.21 16:06, Mel Gorman wrote: > >>> Mike Galbraith, Alexey Avramov and Darrick Wong all reported similar > >>> problems due to reclaim throttling for excessive lengths of time. > >>> In Alexey's case, a memory hog that should go OOM quickly stalls for > >>> several minutes before stalling. In Mike and Darrick's cases, a small > >>> memcg environment stalled excessively even though the system had enough > >>> memory overall. > >> > >> Just wondering: this patch afaics is now in -mm and Linux next for > >> nearly two weeks. Is that intentional? I had expected it to be mainlined > >> with the batch of patches Andrew mailed to Linus last week, but it > >> wasn't among them. > > > > I have it queued for 5.17-rc1. > > > > There is still time to squeeze it into 5.16, just, with a cc:stable. > > > > Alternatively we could merge it into 5.17-rc1 with a cc:stable, so it > > will trickle back with less risk to the 5.17 release. > > > > What do people think? > > CCing Linus, to make sure he's aware of this. > > Maybe I'm totally missing something, but I'm a bit confused by what you > wrote, as the regression afaik was introduced between v5.15..v5.16-rc1. > So I assume this is what you meant: > > ``` > I have it queued for 5.17-rc1. > > There is still time to squeeze it into 5.16. > > Alternatively we could merge it into 5.17-rc1 with a cc:stable, so it > will trickle back with less risk to the 5.16 release. > > What do people think? > ``` > > I'll leave the individual risk evaluation of the patch to others. If the > fix is risky, waiting for 5.17 is fine for me. > > But hmmm, regarding the "could merge it into 5.17-rc1 with a cc:stable" > idea a remark: is that really "less risk", as your stated? > > If we get it into rc8 (which is still possible, even if a bit hard due > to the new year festivities), it will get at least one week of testing. My vote is for it to go into rc8: for me, 5.16-rc reclaim behaves too oddly without it, so I've simply added it into whatever testing I do ever since Mel posted - no regressions noticed with it in (aside from needing the -fix.patch you already added a few weeks ago). Hugh > > If the fix waits for the next merge window, it all depends on the how > the timing works out. But it's easy to picture a worst case: the fix is > only merged on the Friday evening before Linus releases 5.17-rc1 and > right after it's out makes it into a stable-rc (say a day or two after > 5.17-rc1 is out) and from there into a 5.16.y release on Thursday. That > IMHO would mean less days of testing in the end (and there is a weekend > in this period as well). > > Waiting obviously will also mean that users of 5.16 and 5.16.y will > likely have to face this regression for at least two and a half weeks, > unless you send the fix early and Greg backports it before rc1 (which he > afaics does if there are good reasons). Yes, it's `just` a performance > regression, so it might not stop anyone from running Linux 5.16 -- but > it's one that three people separately reported in the 5.16 devel cycle, > so others will likely encounter it as well if we leave it unfixed in > 5.16. This will likely annoy some people, especially if they invest time > in bisecting it, only to find out that the forth iteration of the fix > for the regression is already available since December the 2nd. > > Ciao, Thorsten
