On Thu, Dec 20, 2012 at 4:49 PM, Michel Lespinasse <walken@xxxxxxxxxx> wrote: > We have many vma manipulation functions that are fast in the typical case, > but can optionally be instructed to populate an unbounded number of ptes > within the region they work on: > - mmap with MAP_POPULATE or MAP_LOCKED flags; > - remap_file_pages() with MAP_NONBLOCK not set or when working on a > VM_LOCKED vma; > - mmap_region() and all its wrappers when mlock(MCL_FUTURE) is in effect; > - brk() when mlock(MCL_FUTURE) is in effect. > Something's buggy here. My evil test case is stuck with lots of threads spinning at 100% system time. Stack traces look like: [<0000000000000000>] __mlock_vma_pages_range+0x66/0x70 [<0000000000000000>] __mm_populate+0xf9/0x150 [<0000000000000000>] vm_mmap_pgoff+0x9f/0xc0 [<0000000000000000>] sys_mmap_pgoff+0x7e/0x150 [<0000000000000000>] sys_mmap+0x22/0x30 [<0000000000000000>] system_call_fastpath+0x16/0x1b [<0000000000000000>] 0xffffffffffffffff perf top says: 38.45% [kernel] [k] __mlock_vma_pages_range 33.04% [kernel] [k] __get_user_pages 28.18% [kernel] [k] __mm_populate The tasks in question use MCL_FUTURE but not MAP_POPULATE. These tasks are immune to SIGKILL. --Andy -- 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>