On Thu, 6 Aug 2020 15:45:14 +0800 Muchun Song <songmuchun@xxxxxxxxxxxxx> wrote: > On Tue, Jul 28, 2020 at 11:49 AM 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". > > > > Signed-off-by: Muchun Song <songmuchun@xxxxxxxxxxxxx> > > Reported-by: Jianchao Guo <guojianchao@xxxxxxxxxxxxx> > > Suggested-by: Michal Hocko <mhocko@xxxxxxxxxx> > > Reviewed-by: Mike Kravetz <mike.kravetz@xxxxxxxxxx> > > Hi Andrew, > > Any comments or forgot to add this to the queue for the > merge window? I think Baoquan He's comment threw me off. I worry about the use of `current' in mempolicy.h. It's the first time this header has referenced current and the patch forgot to include sched.h to get the definition. Presumably it works by accident. I could toss in the #include but sometimes that blows up. But it's unlikely that we'll be getting circular includes or other such nastiness between those two header files, so fingers crossed... --- a/include/linux/mempolicy.h~mm-hugetlb-add-mempolicy-check-in-the-reservation-routine-fix +++ a/include/linux/mempolicy.h @@ -6,7 +6,7 @@ #ifndef _LINUX_MEMPOLICY_H #define _LINUX_MEMPOLICY_H 1 - +#include <linux/sched.h> #include <linux/mmzone.h> #include <linux/dax.h> #include <linux/slab.h> _
