On Thu, 2014-01-30 at 10:59 +0100, Michal Hocko wrote: > On Wed 29-01-14 22:37:03, Davidlohr Bueso wrote: > > From: Davidlohr Bueso <davidlohr@xxxxxx> > > > > While testing some changes, I noticed an issue triggered by the libhugetlbfs > > test-suite. This is caused by commit 309381fe (mm: dump page when hitting a > > VM_BUG_ON using VM_BUG_ON_PAGE), where an application can unexpectedly OOM due > > to another program that using, or reserving, pool_size-1 pages later triggers > > a VM_BUG_ON_PAGE and thus greedly leaves no memory to the rest of the hugetlb > > aware tasks. For example, in libhugetlbfs 2.14: > > > > mmap-gettest 10 32783 (2M: 64): <---- hit VM_BUG_ON_PAGE > > mmap-cow 32782 32783 (2M: 32): FAIL Failed to create shared mapping: Cannot allocate memory > > mmap-cow 32782 32783 (2M: 64): FAIL Failed to create shared mapping: Cannot allocate memory > > > > While I have not looked into why 'mmap-gettest' keeps failing, it is of no > > importance to this particular issue. This problem is similar to why we have > > the hugetlb_instantiation_mutex, hugepages are quite finite. > > > > Revert the use of VM_BUG_ON_PAGE back to just VM_BUG_ON. > > I do not understand what VM_BUG_ON_PAGE has to do with the above > failure. Could you be more specific. > > Hmm, now that I am looking into dump_page_badflags it shouldn't call > mem_cgroup_print_bad_page for hugetlb pages because it doesn't make any > sense. I will post a patch for that but that still doesn't explain the > above changelog. Yeah, I then looked closer at it and realized it doesn't make much sense. I don't know why I thought a new page was being used. In any case, bisection still shows the commit in question as the cause of the regression. I will continue looking into it. -- 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>