| Message ID | 20190109020203.26669-2-aarcange@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | mm/hugetlb.c: teach follow_hugetlb_page() to handle FOLL_NOWAIT | expand |
On 1/8/19 6:02 PM, Andrea Arcangeli wrote: > hugetlb needs the same fix as faultin_nopage (which was applied in > 96312e61282ae3f6537a562625706498cbc75594) or KVM hangs because it > thinks the mmap_sem was already released by hugetlb_fault() if it > returned VM_FAULT_RETRY, but it wasn't in the FOLL_NOWAIT case. > > Fixes: ce53053ce378 ("kvm: switch get_user_page_nowait() to get_user_pages_unlocked()") > Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> > Tested-by: "Dr. David Alan Gilbert" <dgilbert@redhat.com> > Reported-by: "Dr. David Alan Gilbert" <dgilbert@redhat.com> Thanks for fixing this. Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
On Tue, Jan 08, 2019 at 09:02:03PM -0500, Andrea Arcangeli wrote: > hugetlb needs the same fix as faultin_nopage (which was applied in > 96312e61282ae3f6537a562625706498cbc75594) or KVM hangs because it > thinks the mmap_sem was already released by hugetlb_fault() if it > returned VM_FAULT_RETRY, but it wasn't in the FOLL_NOWAIT case. > > Fixes: ce53053ce378 ("kvm: switch get_user_page_nowait() to get_user_pages_unlocked()") > Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> > Tested-by: "Dr. David Alan Gilbert" <dgilbert@redhat.com> > Reported-by: "Dr. David Alan Gilbert" <dgilbert@redhat.com> FWIW: Reviewed-by: Peter Xu <peterx@redhat.com> > --- > mm/hugetlb.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/mm/hugetlb.c b/mm/hugetlb.c > index e37efd5d8318..b3622d7888c8 100644 > --- a/mm/hugetlb.c > +++ b/mm/hugetlb.c > @@ -4301,7 +4301,8 @@ long follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma, > break; > } > if (ret & VM_FAULT_RETRY) { > - if (nonblocking) > + if (nonblocking && > + !(fault_flags & FAULT_FLAG_RETRY_NOWAIT)) > *nonblocking = 0; > *nr_pages = 0; > /* Regards,
diff --git a/mm/hugetlb.c b/mm/hugetlb.c index e37efd5d8318..b3622d7888c8 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -4301,7 +4301,8 @@ long follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma, break; } if (ret & VM_FAULT_RETRY) { - if (nonblocking) + if (nonblocking && + !(fault_flags & FAULT_FLAG_RETRY_NOWAIT)) *nonblocking = 0; *nr_pages = 0; /*
hugetlb needs the same fix as faultin_nopage (which was applied in 96312e61282ae3f6537a562625706498cbc75594) or KVM hangs because it thinks the mmap_sem was already released by hugetlb_fault() if it returned VM_FAULT_RETRY, but it wasn't in the FOLL_NOWAIT case. Fixes: ce53053ce378 ("kvm: switch get_user_page_nowait() to get_user_pages_unlocked()") Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Tested-by: "Dr. David Alan Gilbert" <dgilbert@redhat.com> Reported-by: "Dr. David Alan Gilbert" <dgilbert@redhat.com> --- mm/hugetlb.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)