On Sat, 25 Jul 2020 16:07:49 +0800 Muchun Song <songmuchun@xxxxxxxxxxxxx> wrote: > In the reservation routine, we only check whether the cpuset meets > the memory allocation requirements. But we ignore the mempolicy of > MPOL_BIND case. If someone mmap hugetlb succeeds, but the subsequent > memory allocation may fail due to mempolicy restrictions and receives > the SIGBUS signal. This can be reproduced by the follow steps. > > 1) Compile the test case. > cd tools/testing/selftests/vm/ > gcc map_hugetlb.c -o map_hugetlb > > 2) Pre-allocate huge pages. Suppose there are 2 numa nodes in the > system. Each node will pre-allocate one huge page. > echo 2 > /proc/sys/vm/nr_hugepages > > 3) Run test case(mmap 4MB). We receive the SIGBUS signal. > numactl --membind=0 ./map_hugetlb 4 > > With this patch applied, the mmap will fail in the step 3) and throw > "mmap: Cannot allocate memory". This doesn't compile with CONFIG_NUMA=n - ther eis no implementation of get_task_policy(). I think it needs more than a simple build fix - can we please rework the patch so that its impact (mainly code size) on non-NUMA machines is minimized?
