On Tue, 18 Dec 2018 14:35:55 -0800 Mike Kravetz <mike.kravetz@xxxxxxxxxx> wrote: > There are two primary issues addressed here: > 1) For shared pmds, huge PTE pointers returned by huge_pte_alloc can become > invalid via a call to huge_pmd_unshare by another thread. > 2) hugetlbfs page faults can race with truncation causing invalid global > reserve counts and state. > Both issues are addressed by expanding the use of i_mmap_rwsem. > > These issues have existed for a long time. They can be recreated with a > test program that causes page fault/truncation races. For simple mappings, > this results in a negative HugePages_Rsvd count. If racing with mappings > that contain shared pmds, we can hit "BUG at fs/hugetlbfs/inode.c:444!" or > Oops! as the result of an invalid memory reference. Still no reviewers or ackers :( I'll queue these for 4.21-rc1. The Fixes: commits are over a decade old so I assume things aren't super-urgent and the cc:stable will do its work.
