https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=248008
--- Comment #1 from Rick Macklem <[email protected]> --- Created attachment 216478 --> https://bugs.freebsd.org/bugzilla/attachment.cgi?id=216478&action=edit Ryan Libby's suggestion #2 way to fix this When doing a kernel build over NFS, I could frequently get the system hung with many processes sleeping on btalloc. Ryan Libby made the following suggestions: I think the patch is not complete. It looks like the problem is that for systems that do not have UMA_MD_SMALL_ALLOC, we do uma_zone_set_allocf(vmem_bt_zone, vmem_bt_alloc); but we haven't set an appropriate free function. This is probably why UMA_ZONE_NOFREE was originally there. When NOFREE was removed, it was appropriate for systems with uma_small_alloc. So by default we get page_free as our free function. That calls kmem_free, which calls vmem_free ... but we do our allocs with vmem_xalloc. I'm not positive, but I think the problem is that in effect we vmem_xalloc -> vmem_free, not vmem_xfree. Three possible fixes: 1: The one you tested, but this is not best for systems with uma_small_alloc. 2: Pass UMA_ZONE_NOFREE conditional on UMA_MD_SMALL_ALLOC. 3: Actually provide an appropriate vmem_bt_free function. I think we should just do option 2 with a comment, it's simple and it's what we used to do. I'm not sure how much benefit we would see from option 3, but it's more work. This patch implements #2 and seems to fix the problem. The problem was not reproducible on an amd64 system with memory set to 1Gbyte. -- You are receiving this mail because: You are the assignee for the bug. _______________________________________________ [email protected] mailing list https://lists.freebsd.org/mailman/listinfo/freebsd-bugs To unsubscribe, send any mail to "[email protected]"
