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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>
This commit is contained in:
Dominik Dingel 2016-01-15 16:57:07 -08:00 committed by Linus Torvalds
parent 4a9e1cda27
commit fef8953ae4
1 changed files with 26 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

29
arch/s390/mm/pgtable.c
View File

@ -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 @@ int set_guest_storage_key(struct mm_struct *mm, unsigned long addr,
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;
}