On Fri, Jul 21, 2023, Isaku Yamahata wrote:

On Fri, Jul 21, 2023 at 02:13:14PM +0800,
Yuan Yao [off-list ref] wrote:

quoted

quoted

+static int kvm_gmem_error_page(struct address_space *mapping, struct page *page)
+{
+	struct list_head *gmem_list = &mapping->private_list;
+	struct kvm_memory_slot *slot;
+	struct kvm_gmem *gmem;
+	unsigned long index;
+	pgoff_t start, end;
+	gfn_t gfn;
+
+	filemap_invalidate_lock_shared(mapping);
+
+	start = page->index;
+	end = start + thp_nr_pages(page);
+
+	list_for_each_entry(gmem, gmem_list, entry) {
+		xa_for_each_range(&gmem->bindings, index, slot, start, end - 1) {
+			for (gfn = start; gfn < end; gfn++) {

Why the start end range used as gfn here ?

Math is hard?  I almost always mess up these types of things, and then catch my
bugs via tests.  But I don't have tests for this particular flow...   Which
reminds me, we need tests for this :-)  Hopefully error injection provides most
of what we need?

quoted

the page->index is offset of inode's page cache mapping and
gmem address space, IIUC, gfn calculation should follow same
way as kvm_gmem_invalidate_begin().

Also instead of sending signal multiple times, we can utilize lsb argument.

As Vishal pointed out, this code shouldn't be sending signals in the first place.