On Fri, 17 Feb 2012 23:14:01 -0800 (PST) Hugh Dickins <hughd@xxxxxxxxxx> wrote: > On Sat, 18 Feb 2012, Konstantin Khlebnikov wrote: > > Hugh Dickins wrote: > > > On Thu, 16 Feb 2012, Hugh Dickins wrote: > > > > > > > > Yours are not the only patches I was testing in that tree, I tried to > > > > gather several other series which I should be reviewing if I ever have > > > > time: Kamezawa-san's page cgroup diet 6, Xiao Guangrong's 4 prio_tree > > > > cleanups, your 3 radix_tree changes, your 6 shmem changes, your 4 memcg > > > > miscellaneous, and then your 15 books. > > > > > > > > The tree before your final 15 did well under pressure, until I tried to > > > > rmdir one of the cgroups afterwards: then it crashed nastily, I'll have > > > > to bisect into that, probably either Kamezawa's or your memcg changes. > > > > > > So far I haven't succeeded in reproducing that at all: it was real, > > > but obviously harder to get than I assumed - indeed, no good reason > > > to associate it with any of those patches, might even be in 3.3-rc. > > > > > > It did involve a NULL pointer dereference in mem_cgroup_page_lruvec(), > > > somewhere below compact_zone() - but repercussions were causing the > > > stacktrace to scroll offscreen, so I didn't get good details. > > > > There some stupid bugs in my v1 patchset, it shouldn't works at all. > > I did not expect that someone will try to use it. I sent it just to discuss. > > Yes, but as I said, that bug appeared before I put your patchset (the 15) on. > Hm, NULL pointer dereference in mem_cgroup_page_lruvec() via comaction tend to mean pc->mem_cgroup was NULL... IIUC, - compaction get pages from LRU list and isolate/migrate them. So, When pages on LRU were migrated by compact_zone(), pc->mem_cgroup never be NULL.. - All newly allocated pages for migration will be reset by mem_cgroup_reset_owner(). Hm, something unexpected happens.. Regards, -Kame -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>