On Wed, Apr 08, 2015 at 02:16:05PM -0700, Mike Kravetz wrote: > On 04/08/2015 09:15 AM, Shawn Bohrer wrote: > >I've noticed on a number of my systems that after shutting down my > >application that uses huge pages that I'm left with some pages still > >in HugePages_Rsvd. It is possible that I still have something using > >huge pages that I'm not aware of but so far my attempts to find > >anything using huge pages have failed. I've run some simple tests > >using map_hugetlb.c from the kernel source and can see that pages that > >have been reserved but not allocated still show up in > >/proc/<pid>/smaps and /proc/<pid>/numa_maps. Are there any cases > >where this is not true? > > Just a quick question. Are you using hugetlb filesystem(s)? I can't say for sure that nothing is using hugetlbfs. It is mounted but as far as I can tell on the affected system(s) it is empty. [root@dev106 ~]# grep hugetlbfs /proc/mounts hugetlbfs /dev/hugepages hugetlbfs rw,relatime 0 0 [root@dev106 ~]# ls -al /dev/hugepages/ total 0 drwxr-xr-x 2 root root 0 Apr 8 16:22 . drwxr-xr-x 16 root root 4360 Apr 8 03:53 .. [root@dev106 ~]# lsof | grep hugepages > If so, you might want to take a look at files residing in the > filesystem(s). As an experiment, I had a program do a simple > mmap() of a file in a hugetlb filesystem. The program just > created the mapping, and did not actually fault/allocate any > huge pages. The result was the reservation (HugePages_Rsvd) > of sufficient huge pages to cover the mapping. When the program > exited, the reservations remained. If I remove (unlink) the > file the reservations will be removed. That makes sense but I don't think it is the issue here. Thanks, Shawn -- 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>