On 2023/11/23 23:33, Matthew Wilcox wrote:
On Thu, Nov 23, 2023 at 05:09:04PM +0800, zhangpeng (AS) wrote:
+ pte_t *ptep = pte_offset_map_lock(vmf->vma->vm_mm, vmf->pmd,
+ vmf->address, &vmf->ptl);
+ if (ptep) {
+ /*
+ * Recheck pte with ptl locked as the pte can be cleared
+ * temporarily during a read/modify/write update.
+ */
+ if (unlikely(!pte_none(ptep_get(ptep))))
+ ret = VM_FAULT_NOPAGE;
+ pte_unmap_unlock(ptep, vmf->ptl);
+ if (unlikely(ret))
+ return ret;
+ }
+
Need to deal with ptep == NULL. Although that is high impossible.
If ptep == NULL, we may just need to return VM_FAULT_SIGBUS.
I'll add it in the next version.
no? wouldn't ptep being NULL mean that the ptep has been replaced with
a PMD entry, and thus should return NOPAGE?
Yes, ptep == NULL means that the ptep has been replaced with a PMD entry.
I'll add return NOPAGE in the next version.
Thanks!
--
Best Regards,
Peng
