On Fri, 21 Jul 2017 15:45:00 -0700 Tim Chen <tim.c.chen@xxxxxxxxxxxxxxx> wrote: > Memory allocations can happen before the swap_slots cache initialization > is completed during cpu bring up. If we are low on memory, we could call > get_swap_page and access swap_slots_cache before it is fully initialized. > > Add a check in get_swap_page for initialized swap_slots_cache > to prevent this condition. Similar check already exists in > free_swap_slot. Also annotate the checks to indicate the likely > condition. > > We also added a memory barrier to make sure that the locks > initialization are done before the assignment of cache->slots > and cache->slots_ret pointers. This ensures the assumption > that it is safe to acquire the slots cache locks and use the slots > cache when the corresponding cache->slots or cache->slots_ret > pointers are non null. I guess that the user-visible effect is "crash on boot on large machine". Or something. Please don't make me guess! Which kernel version(s) do you believe need this patch, and why? -- 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>
