kernel/git/stable/linux-stable.git/mm/userfaultfd.c, branch linux-4.14.y

mm: userfaultfd: fix missing cache flush in mcopy_atomic_pte() and __mcopy_atomic()

2022-05-15T17:40:27+00:00

commit 7c25a0b89a487878b0691e6524fb5a8827322194 upstream. userfaultfd calls mcopy_atomic_pte() and __mcopy_atomic() which do not do any cache flushing for the target page. Then the target page will be mapped to the user space with a different address (user address), which might have an alias issue with the kernel address used to copy the data from the user to. Fix this by insert flush_dcache_page() after copy_from_user() succeeds. Link: https://lkml.kernel.org/r/20220210123058.79206-7-songmuchun@bytedance.com Fixes: b6ebaedb4cb1 ("userfaultfd: avoid mmap_sem read recursion in mcopy_atomic") Fixes: c1a4de99fada ("userfaultfd: mcopy_atomic|mfill_zeropage: UFFDIO_COPY|UFFDIO_ZEROPAGE preparation") Signed-off-by: Muchun Song Cc: Axel Rasmussen Cc: David Rientjes Cc: Fam Zheng Cc: Kirill A. Shutemov Cc: Lars Persson Cc: Mike Kravetz Cc: Peter Xu Cc: Xiongchun Duan Cc: Zi Yan Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

hugetlbfs: hugetlb_fault_mutex_hash() cleanup

2021-06-03T06:36:25+00:00

commit 552546366a30d88bd1d6f5efe848b2ab50fd57e5 upstream. A new clang diagnostic (-Wsizeof-array-div) warns about the calculation to determine the number of u32's in an array of unsigned longs. Suppress warning by adding parentheses. While looking at the above issue, noticed that the 'address' parameter to hugetlb_fault_mutex_hash is no longer used. So, remove it from the definition and all callers. No functional change. Link: http://lkml.kernel.org/r/20190919011847.18400-1-mike.kravetz@oracle.com Signed-off-by: Mike Kravetz Reported-by: Nathan Chancellor Reviewed-by: Nathan Chancellor Reviewed-by: Davidlohr Bueso Reviewed-by: Andrew Morton Cc: Nick Desaulniers Cc: Ilie Halip Cc: David Bolvansky Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

hugetlb: use same fault hash key for shared and private mappings

2019-05-31T13:47:12+00:00

commit 1b426bac66e6cc83c9f2d92b96e4e72acf43419a upstream. hugetlb uses a fault mutex hash table to prevent page faults of the same pages concurrently. The key for shared and private mappings is different. Shared keys off address_space and file index. Private keys off mm and virtual address. Consider a private mappings of a populated hugetlbfs file. A fault will map the page from the file and if needed do a COW to map a writable page. Hugetlbfs hole punch uses the fault mutex to prevent mappings of file pages. It uses the address_space file index key. However, private mappings will use a different key and could race with this code to map the file page. This causes problems (BUG) for the page cache remove code as it expects the page to be unmapped. A sample stack is: page dumped because: VM_BUG_ON_PAGE(page_mapped(page)) kernel BUG at mm/filemap.c:169! ... RIP: 0010:unaccount_page_cache_page+0x1b8/0x200 ... Call Trace: __delete_from_page_cache+0x39/0x220 delete_from_page_cache+0x45/0x70 remove_inode_hugepages+0x13c/0x380 ? __add_to_page_cache_locked+0x162/0x380 hugetlbfs_fallocate+0x403/0x540 ? _cond_resched+0x15/0x30 ? __inode_security_revalidate+0x5d/0x70 ? selinux_file_permission+0x100/0x130 vfs_fallocate+0x13f/0x270 ksys_fallocate+0x3c/0x80 __x64_sys_fallocate+0x1a/0x20 do_syscall_64+0x5b/0x180 entry_SYSCALL_64_after_hwframe+0x44/0xa9 There seems to be another potential COW issue/race with this approach of different private and shared keys as noted in commit 8382d914ebf7 ("mm, hugetlb: improve page-fault scalability"). Since every hugetlb mapping (even anon and private) is actually a file mapping, just use the address_space index key for all mappings. This results in potentially more hash collisions. However, this should not be the common case. Link: http://lkml.kernel.org/r/20190328234704.27083-3-mike.kravetz@oracle.com Link: http://lkml.kernel.org/r/20190412165235.t4sscoujczfhuiyt@linux-r8p5 Fixes: b5cec28d36f5 ("hugetlbfs: truncate_hugepages() takes a range of pages") Signed-off-by: Mike Kravetz Reviewed-by: Naoya Horiguchi Reviewed-by: Davidlohr Bueso Cc: Joonsoo Kim Cc: "Kirill A . Shutemov" Cc: Michal Hocko Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

userfaultfd: shmem/hugetlbfs: only allow to register VM_MAYWRITE vmas

2018-12-08T12:03:38+00:00

commit 29ec90660d68bbdd69507c1c8b4e33aa299278b1 upstream. After the VMA to register the uffd onto is found, check that it has VM_MAYWRITE set before allowing registration. This way we inherit all common code checks before allowing to fill file holes in shmem and hugetlbfs with UFFDIO_COPY. The userfaultfd memory model is not applicable for readonly files unless it's a MAP_PRIVATE. Link: http://lkml.kernel.org/r/20181126173452.26955-4-aarcange@redhat.com Fixes: ff62a3421044 ("hugetlb: implement memfd sealing") Signed-off-by: Andrea Arcangeli Reviewed-by: Mike Rapoport Reviewed-by: Hugh Dickins Reported-by: Jann Horn Fixes: 4c27fe4c4c84 ("userfaultfd: shmem: add shmem_mcopy_atomic_pte for userfaultfd support") Cc: Cc: "Dr. David Alan Gilbert" Cc: Mike Kravetz Cc: Peter Xu Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

userfaultfd: shmem: add i_size checks

2018-12-08T12:03:37+00:00

commit e2a50c1f64145a04959df2442305d57307e5395a upstream. With MAP_SHARED: recheck the i_size after taking the PT lock, to serialize against truncate with the PT lock. Delete the page from the pagecache if the i_size_read check fails. With MAP_PRIVATE: check the i_size after the PT lock before mapping anonymous memory or zeropages into the MAP_PRIVATE shmem mapping. A mostly irrelevant cleanup: like we do the delete_from_page_cache() pagecache removal after dropping the PT lock, the PT lock is a spinlock so drop it before the sleepable page lock. Link: http://lkml.kernel.org/r/20181126173452.26955-5-aarcange@redhat.com Fixes: 4c27fe4c4c84 ("userfaultfd: shmem: add shmem_mcopy_atomic_pte for userfaultfd support") Signed-off-by: Andrea Arcangeli Reviewed-by: Mike Rapoport Reviewed-by: Hugh Dickins Reported-by: Jann Horn Cc: Cc: "Dr. David Alan Gilbert" Cc: Mike Kravetz Cc: Peter Xu Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

userfaultfd: shmem: allocate anonymous memory for MAP_PRIVATE shmem

2018-12-08T12:03:37+00:00

commit 5b51072e97d587186c2f5390c8c9c1fb7e179505 upstream. Userfaultfd did not create private memory when UFFDIO_COPY was invoked on a MAP_PRIVATE shmem mapping. Instead it wrote to the shmem file, even when that had not been opened for writing. Though, fortunately, that could only happen where there was a hole in the file. Fix the shmem-backed implementation of UFFDIO_COPY to create private memory for MAP_PRIVATE mappings. The hugetlbfs-backed implementation was already correct. This change is visible to userland, if userfaultfd has been used in unintended ways: so it introduces a small risk of incompatibility, but is necessary in order to respect file permissions. An app that uses UFFDIO_COPY for anything like postcopy live migration won't notice the difference, and in fact it'll run faster because there will be no copy-on-write and memory waste in the tmpfs pagecache anymore. Userfaults on MAP_PRIVATE shmem keep triggering only on file holes like before. The real zeropage can also be built on a MAP_PRIVATE shmem mapping through UFFDIO_ZEROPAGE and that's safe because the zeropage pte is never dirty, in turn even an mprotect upgrading the vma permission from PROT_READ to PROT_READ|PROT_WRITE won't make the zeropage pte writable. Link: http://lkml.kernel.org/r/20181126173452.26955-3-aarcange@redhat.com Fixes: 4c27fe4c4c84 ("userfaultfd: shmem: add shmem_mcopy_atomic_pte for userfaultfd support") Signed-off-by: Andrea Arcangeli Reported-by: Mike Rapoport Reviewed-by: Hugh Dickins Cc: Cc: "Dr. David Alan Gilbert" Cc: Jann Horn Cc: Mike Kravetz Cc: Peter Xu Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

userfaultfd: use ENOENT instead of EFAULT if the atomic copy user fails

2018-12-08T12:03:37+00:00

commit 9e368259ad988356c4c95150fafd1a06af095d98 upstream. Patch series "userfaultfd shmem updates". Jann found two bugs in the userfaultfd shmem MAP_SHARED backend: the lack of the VM_MAYWRITE check and the lack of i_size checks. Then looking into the above we also fixed the MAP_PRIVATE case. Hugh by source review also found a data loss source if UFFDIO_COPY is used on shmem MAP_SHARED PROT_READ mappings (the production usages incidentally run with PROT_READ|PROT_WRITE, so the data loss couldn't happen in those production usages like with QEMU). The whole patchset is marked for stable. We verified QEMU postcopy live migration with guest running on shmem MAP_PRIVATE run as well as before after the fix of shmem MAP_PRIVATE. Regardless if it's shmem or hugetlbfs or MAP_PRIVATE or MAP_SHARED, QEMU unconditionally invokes a punch hole if the guest mapping is filebacked and a MADV_DONTNEED too (needed to get rid of the MAP_PRIVATE COWs and for the anon backend). This patch (of 5): We internally used EFAULT to communicate with the caller, switch to ENOENT, so EFAULT can be used as a non internal retval. Link: http://lkml.kernel.org/r/20181126173452.26955-2-aarcange@redhat.com Fixes: 4c27fe4c4c84 ("userfaultfd: shmem: add shmem_mcopy_atomic_pte for userfaultfd support") Signed-off-by: Andrea Arcangeli Reviewed-by: Mike Rapoport Reviewed-by: Hugh Dickins Cc: Mike Kravetz Cc: Jann Horn Cc: Peter Xu Cc: "Dr. David Alan Gilbert" Cc: Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

userfaultfd: shmem: wire up shmem_mfill_zeropage_pte

2017-09-07T00:27:28+00:00

For shmem VMAs we can use shmem_mfill_zeropage_pte for UFFDIO_ZEROPAGE Link: http://lkml.kernel.org/r/1497939652-16528-6-git-send-email-rppt@linux.vnet.ibm.com Signed-off-by: Mike Rapoport Cc: "Kirill A. Shutemov" Cc: Andrea Arcangeli Cc: Hillf Danton Cc: Hugh Dickins Cc: Pavel Emelyanov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

userfaultfd: mcopy_atomic: introduce mfill_atomic_pte helper

2017-09-07T00:27:28+00:00

Shuffle the code a bit to improve readability. Link: http://lkml.kernel.org/r/1497939652-16528-5-git-send-email-rppt@linux.vnet.ibm.com Signed-off-by: Mike Rapoport Cc: "Kirill A. Shutemov" Cc: Andrea Arcangeli Cc: Hillf Danton Cc: Hugh Dickins Cc: Pavel Emelyanov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm: convert generic code to 5-level paging

2017-03-09T19:48:47+00:00

Convert all non-architecture-specific code to 5-level paging. It's mostly mechanical adding handling one more page table level in places where we deal with pud_t. Signed-off-by: Kirill A. Shutemov Acked-by: Michal Hocko Signed-off-by: Linus Torvalds