On Tue, Jul 28, 2020 at 8:19 AM Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> wrote: > > 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? > OK. I will do that, thanks. -- Yours, Muchun
