lkml.org 
[lkml]   [2018]   [Mar]   [27]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [PATCH v9 06/24] mm: make pte_unmap_same compatible with SPF
    On Tue, 13 Mar 2018, Laurent Dufour wrote:

    > diff --git a/include/linux/mm.h b/include/linux/mm.h
    > index 2f3e98edc94a..b6432a261e63 100644
    > --- a/include/linux/mm.h
    > +++ b/include/linux/mm.h
    > @@ -1199,6 +1199,7 @@ static inline void clear_page_pfmemalloc(struct page *page)
    > #define VM_FAULT_NEEDDSYNC 0x2000 /* ->fault did not modify page tables
    > * and needs fsync() to complete (for
    > * synchronous page faults in DAX) */
    > +#define VM_FAULT_PTNOTSAME 0x4000 /* Page table entries have changed */
    >
    > #define VM_FAULT_ERROR (VM_FAULT_OOM | VM_FAULT_SIGBUS | VM_FAULT_SIGSEGV | \
    > VM_FAULT_HWPOISON | VM_FAULT_HWPOISON_LARGE | \
    > diff --git a/mm/memory.c b/mm/memory.c
    > index 21b1212a0892..4bc7b0bdcb40 100644
    > --- a/mm/memory.c
    > +++ b/mm/memory.c
    > @@ -2309,21 +2309,29 @@ static bool pte_map_lock(struct vm_fault *vmf)
    > * parts, do_swap_page must check under lock before unmapping the pte and
    > * proceeding (but do_wp_page is only called after already making such a check;
    > * and do_anonymous_page can safely check later on).
    > + *
    > + * pte_unmap_same() returns:
    > + * 0 if the PTE are the same
    > + * VM_FAULT_PTNOTSAME if the PTE are different
    > + * VM_FAULT_RETRY if the VMA has changed in our back during
    > + * a speculative page fault handling.
    > */
    > -static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd,
    > - pte_t *page_table, pte_t orig_pte)
    > +static inline int pte_unmap_same(struct vm_fault *vmf)
    > {
    > - int same = 1;
    > + int ret = 0;
    > +
    > #if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT)
    > if (sizeof(pte_t) > sizeof(unsigned long)) {
    > - spinlock_t *ptl = pte_lockptr(mm, pmd);
    > - spin_lock(ptl);
    > - same = pte_same(*page_table, orig_pte);
    > - spin_unlock(ptl);
    > + if (pte_spinlock(vmf)) {
    > + if (!pte_same(*vmf->pte, vmf->orig_pte))
    > + ret = VM_FAULT_PTNOTSAME;
    > + spin_unlock(vmf->ptl);
    > + } else
    > + ret = VM_FAULT_RETRY;
    > }
    > #endif
    > - pte_unmap(page_table);
    > - return same;
    > + pte_unmap(vmf->pte);
    > + return ret;
    > }
    >
    > static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va, struct vm_area_struct *vma)
    > @@ -2913,7 +2921,8 @@ int do_swap_page(struct vm_fault *vmf)
    > int exclusive = 0;
    > int ret = 0;

    Initialization is now unneeded.

    Otherwise:

    Acked-by: David Rientjes <rientjes@google.com>

    \
     
     \ /
      Last update: 2018-03-27 23:19    [W:3.469 / U:0.856 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site