On Fri, Jun 13, 2014 at 05:26:17PM +0100, Chris Wilson wrote: > When using remap_pfn_range() from a fault handler, we are exposed to > races between concurrent faults. Rather than hitting a BUG, report the > error back to the caller, like vm_insert_pfn(). > > Signed-off-by: Chris Wilson <[email protected]> > Cc: Andrew Morton <[email protected]> > Cc: "Kirill A. Shutemov" <[email protected]> > Cc: Peter Zijlstra <[email protected]> > Cc: Rik van Riel <[email protected]> > Cc: Mel Gorman <[email protected]> > Cc: Cyrill Gorcunov <[email protected]> > Cc: Johannes Weiner <[email protected]> > Cc: [email protected] > --- > mm/memory.c | 8 ++++++-- > 1 file changed, 6 insertions(+), 2 deletions(-) > > diff --git a/mm/memory.c b/mm/memory.c > index 037b812a9531..6603a9e6a731 100644 > --- a/mm/memory.c > +++ b/mm/memory.c > @@ -2306,19 +2306,23 @@ static int remap_pte_range(struct mm_struct *mm, > pmd_t *pmd, > { > pte_t *pte; > spinlock_t *ptl; > + int ret = 0; > > pte = pte_alloc_map_lock(mm, pmd, addr, &ptl); > if (!pte) > return -ENOMEM; > arch_enter_lazy_mmu_mode(); > do { > - BUG_ON(!pte_none(*pte)); > + if (!pte_none(*pte)) { > + ret = -EBUSY; > + break; > + } > set_pte_at(mm, addr, pte, pte_mkspecial(pfn_pte(pfn, prot))); > pfn++; > } while (pte++, addr += PAGE_SIZE, addr != end); > arch_leave_lazy_mmu_mode(); > pte_unmap_unlock(pte - 1, ptl);
Oh. That will want the EBUSY path to increment pte or we will try to unmap the wrong page. -Chris -- Chris Wilson, Intel Open Source Technology Centre _______________________________________________ Intel-gfx mailing list [email protected] http://lists.freedesktop.org/mailman/listinfo/intel-gfx
