On Wed, 31 Mar 2010 15:00:52 +0900 (JST) KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx> wrote: > > KOSAKI-san, > > > > On Wed, Mar 31, 2010 at 01:38:12PM +0800, KOSAKI Motohiro wrote: > > > > On Tue, Mar 30, 2010 at 02:08:53PM +0800, KOSAKI Motohiro wrote: > > > > > Hi > > > > > > > > > > > Commit 84b18490d1f1bc7ed5095c929f78bc002eb70f26 introduces a regression. > > > > > > With it, our tmpfs test always oom. The test has a lot of rotated anon > > > > > > pages and cause percent[0] zero. Actually the percent[0] is a very small > > > > > > value, but our calculation round it to zero. The commit makes vmscan > > > > > > completely skip anon pages and cause oops. > > > > > > An option is if percent[x] is zero in get_scan_ratio(), forces it > > > > > > to 1. See below patch. > > > > > > But the offending commit still changes behavior. Without the commit, we scan > > > > > > all pages if priority is zero, below patch doesn't fix this. Don't know if > > > > > > It's required to fix this too. > > > > > > > > > > Can you please post your /proc/meminfo and reproduce program? I'll digg it. > > > > > > > > > > Very unfortunately, this patch isn't acceptable. In past time, vmscan > > > > > had similar logic, but 1% swap-out made lots bug reports. > > > > if 1% is still big, how about below patch? > > > > > > This patch makes a lot of sense than previous. however I think <1% anon ratio > > > shouldn't happen anyway because file lru doesn't have reclaimable pages. > > > <1% seems no good reclaim rate. > > > > > > perhaps I'll take your patch for stable tree. but we need to attack the root > > > cause. iow, I guess we need to fix scan ratio equation itself. > > > > I tend to regard this patch as a general improvement for both > > .33-stable and .34. > > > > I do agree with you that it's desirable to do more test&analyze and > > check further for possibly hidden problems. > > Yeah, I don't want ignore .33-stable too. if I can't find the root cause > in 2-3 days, I'll revert guilty patch anyway. > It's a good idea to avoid fixing a bug one-way-in-stable, other-way-in-mainline. Because then we have new code in both trees which is different. And the -stable guys sensibly like to see code get a bit of a shakedown in mainline before backporting it. So it would be better to merge the "simple" patch into mainline, tagged for -stable backporting. Then we can later implement the larger fix in mainline, perhaps starting by reverting the "simple" fix. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>