Am 04.05.2014 22:37, schrieb Hugh Dickins: > On Sat, 3 May 2014, Richard Weinberger wrote: >> On Thu, May 1, 2014 at 6:20 PM, Richard Weinberger >> <richard.weinberger@xxxxxxxxx> wrote: >>> On Wed, Apr 16, 2014 at 10:40 PM, Hugh Dickins <hughd@xxxxxxxxxx> wrote: >>>> >>>> Help! >>> >>> Using a trinity as of today I'm able to trigger this bug on UML within seconds. >>> If you want me to test patch, I can help. >>> >>> I'm also observing one strange fact, I can trigger this on any kernel version. >>> So far I've managed UML to crash on 3.0 to 3.15-rc... >> >> After digging deeper into UML's mmu and tlb code I've found issues and >> fixed them. >> >> But I'm still facing this issue. Although triggering the BUG_ON() is >> not so easy as before >> I can trigger "BUG: Bad rss-counter ..." very easily. >> Now the interesting fact, with my UML mmu and flb fixes applied it >> happens only on kernels >= 3.14. >> If it helps I can try to bisect it. > > Thanks a lot for trying, but from other mail it looks like your > bisection got blown off course ;( Yeah, looks like the issue I'm facing on UML is a completely different story. Although the symptoms are identical. :-( > I expect for the moment you'll want to concentrate on getting UML's > TLB flushing back on track with 3.15-rc. This is what I'm currently doing. But it might take some time as I'm a mm novice. > Once you have that sorted out, I wouldn't be surprised if the same > changes turn out to fix your "Bad rss-counter"s on 3.14 also. > > If not, and if you do still have time to bisect back between 3.13 and > 3.14 to find where things went wrong, it will be a bit tedious in that > you would probably have to apply > > 887843961c4b "mm: fix bad rss-counter if remap_file_pages raced migration" > 7e09e738afd2 "mm: fix swapops.h:131 bug if remap_file_pages raced migration" > > at each stage, to avoid those now-known bugs which trinity became rather > good at triggering. Perhaps other fixes needed, those the two I remember. > > Please don't worry if you don't have time for this, that's understandable. > > Or is UML so contrary that one of those commits actually brings on the > problem for you? Hehe, no. I gave it a quick try, both 887843961c4b and 7e09e738afd2 seem to be unrelated to the issues I see. Thanks, //richard -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>