diff options
Diffstat (limited to 'arch/s390/mm/pgtable.c')
| -rw-r--r-- | arch/s390/mm/pgtable.c | 29 |
1 files changed, 26 insertions, 3 deletions
diff --git a/arch/s390/mm/pgtable.c b/arch/s390/mm/pgtable.c index 84bddda8d412..a809fa8e6f8b 100644 --- a/arch/s390/mm/pgtable.c +++ b/arch/s390/mm/pgtable.c @@ -578,17 +578,29 @@ int gmap_fault(struct gmap *gmap, unsigned long gaddr, { unsigned long vmaddr; int rc; + bool unlocked; down_read(&gmap->mm->mmap_sem); + +retry: + unlocked = false; vmaddr = __gmap_translate(gmap, gaddr); if (IS_ERR_VALUE(vmaddr)) { rc = vmaddr; goto out_up; } - if (fixup_user_fault(current, gmap->mm, vmaddr, fault_flags, NULL)) { + if (fixup_user_fault(current, gmap->mm, vmaddr, fault_flags, + &unlocked)) { rc = -EFAULT; goto out_up; } + /* + * In the case that fixup_user_fault unlocked the mmap_sem during + * faultin redo __gmap_translate to not race with a map/unmap_segment. + */ + if (unlocked) + goto retry; + rc = __gmap_link(gmap, gaddr, vmaddr); out_up: up_read(&gmap->mm->mmap_sem); @@ -714,12 +726,14 @@ int gmap_ipte_notify(struct gmap *gmap, unsigned long gaddr, unsigned long len) spinlock_t *ptl; pte_t *ptep, entry; pgste_t pgste; + bool unlocked; int rc = 0; if ((gaddr & ~PAGE_MASK) || (len & ~PAGE_MASK)) return -EINVAL; down_read(&gmap->mm->mmap_sem); while (len) { + unlocked = false; /* Convert gmap address and connect the page tables */ addr = __gmap_translate(gmap, gaddr); if (IS_ERR_VALUE(addr)) { @@ -728,10 +742,13 @@ int gmap_ipte_notify(struct gmap *gmap, unsigned long gaddr, unsigned long len) } /* Get the page mapped */ if (fixup_user_fault(current, gmap->mm, addr, FAULT_FLAG_WRITE, - NULL)) { + &unlocked)) { rc = -EFAULT; break; } + /* While trying to map mmap_sem got unlocked. Let us retry */ + if (unlocked) + continue; rc = __gmap_link(gmap, gaddr, addr); if (rc) break; @@ -792,9 +809,11 @@ int set_guest_storage_key(struct mm_struct *mm, unsigned long addr, spinlock_t *ptl; pgste_t old, new; pte_t *ptep; + bool unlocked; down_read(&mm->mmap_sem); retry: + unlocked = false; ptep = get_locked_pte(mm, addr, &ptl); if (unlikely(!ptep)) { up_read(&mm->mmap_sem); @@ -803,8 +822,12 @@ retry: if (!(pte_val(*ptep) & _PAGE_INVALID) && (pte_val(*ptep) & _PAGE_PROTECT)) { pte_unmap_unlock(ptep, ptl); + /* + * We do not really care about unlocked. We will retry either + * way. But this allows fixup_user_fault to enable userfaultfd. + */ if (fixup_user_fault(current, mm, addr, FAULT_FLAG_WRITE, - NULL)) { + &unlocked)) { up_read(&mm->mmap_sem); return -EFAULT; } |