Michal Hocko <mhocko@xxxxxxxx> writes:
> On Tue 20-02-24 15:22:07, Huang, Ying wrote:
> [...]
>> This isn't an issue now, because mpol_misplaced() are always called with
>> PTL held. And, we can still keep thiscpu local variable.
>
> yes, this is the case but it would be better if we made that assumption
> official by lockdep_assert_held
>
How about this folded into this patch?
2 files changed, 12 insertions(+), 4 deletions(-)
mm/memory.c | 6 ++++--
mm/mempolicy.c | 10 ++++++++--
modified mm/memory.c
@@ -4879,9 +4879,11 @@ static vm_fault_t do_fault(struct vm_fault *vmf)
return ret;
}
-int numa_migrate_prep(struct folio *folio, struct vm_area_struct *vma,
+int numa_migrate_prep(struct folio *folio, struct vm_fault *vmf,
unsigned long addr, int page_nid, int *flags)
{
+ struct vm_area_struct *vma = vmf->vma;
+
folio_get(folio);
/* Record the current PID acceesing VMA */
@@ -4893,7 +4895,7 @@ int numa_migrate_prep(struct folio *folio, struct vm_area_struct *vma,
*flags |= TNF_FAULT_LOCAL;
}
- return mpol_misplaced(folio, vma, addr);
+ return mpol_misplaced(folio, vmf, addr);
}
static vm_fault_t do_numa_page(struct vm_fault *vmf)
modified mm/mempolicy.c
@@ -2495,18 +2495,24 @@ static inline bool mpol_preferred_should_numa_migrate(int exec_node, int folio_n
* Return: NUMA_NO_NODE if the page is in a node that is valid for this
* policy, or a suitable node ID to allocate a replacement folio from.
*/
-int mpol_misplaced(struct folio *folio, struct vm_area_struct *vma,
+int mpol_misplaced(struct folio *folio, struct vm_fault *vmf,
unsigned long addr)
{
struct mempolicy *pol;
pgoff_t ilx;
struct zoneref *z;
int curnid = folio_nid(folio);
+ struct vm_area_struct *vma = vmf->vma;
int thiscpu = raw_smp_processor_id();
- int thisnid = cpu_to_node(thiscpu);
+ int thisnid = numa_node_id();
int polnid = NUMA_NO_NODE;
int ret = NUMA_NO_NODE;
+ /*
+ * Make sure ptl is held so that we don't preempt and we
+ * have a stable smp processor id
+ */
+ lockdep_assert_held(vmf->ptl);
pol = get_vma_policy(vma, addr, folio_order(folio), &ilx);
if (!(pol->flags & MPOL_F_MOF))
goto out;
[back]
