diff options
author | Dominik Dingel <dingel@linux.vnet.ibm.com> | 2016-01-15 16:57:07 -0800 |
---|---|---|
committer | Linus Torvalds <torvalds@linux-foundation.org> | 2016-01-15 17:56:32 -0800 |
commit | fef8953ae4e2b87392434a1a3774694c3f8164f6 (patch) | |
tree | fbfe75ac80473261d7ebc6146ac614759563f1d4 /arch/s390/mm/pgtable.c | |
parent | 4a9e1cda274893eca7d178d7dc265503ccb9d87a (diff) | |
download | linux-fef8953ae4e2b87392434a1a3774694c3f8164f6.tar.bz2 |
s390/mm: enable fixup_user_fault retrying
By passing a non-null flag we allow fixup_user_fault to retry, which
enables userfaultfd. As during these retries we might drop the mmap_sem
we need to check if that happened and redo the complete chain of
actions.
Signed-off-by: Dominik Dingel <dingel@linux.vnet.ibm.com>
Reviewed-by: Andrea Arcangeli <aarcange@redhat.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: "Jason J. Herne" <jjherne@linux.vnet.ibm.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Eric B Munson <emunson@akamai.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Dominik Dingel <dingel@linux.vnet.ibm.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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; } |