Commit fef8953a authored by Dominik Dingel's avatar Dominik Dingel Committed by Linus Torvalds
Browse files

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: default avatarDominik Dingel <dingel@linux.vnet.ibm.com>
Reviewed-by: default avatarAndrea 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: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 4a9e1cda

arch/s390/mm/pgtable.c

+26 −3
Original line number Diff line number Diff line
@@ -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;

		}

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