Merge tag 'usb-6.4-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb

Pull USB fixes from Greg KH:
 "Here are some USB driver and core fixes for 6.4-rc5. Most of these are
  tiny driver fixes, including:

   - udc driver bugfix

   - f_fs gadget driver bugfix

   - cdns3 driver bugfix

   - typec bugfixes

  But the "big" thing in here is a fix yet-again for how the USB buffers
  are handled from userspace when dealing with DMA issues. The changes
  were discussed a lot, and tested a lot, on the list, and acked by the
  relevant mm maintainers and have been in linux-next all this past week
  with no reported problems"

* tag 'usb-6.4-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb:
  usb: typec: tps6598x: Fix broken polling mode after system suspend/resume
  mm: page_table_check: Ensure user pages are not slab pages
  mm: page_table_check: Make it dependent on EXCLUSIVE_SYSTEM_RAM
  usb: usbfs: Use consistent mmap functions
  usb: usbfs: Enforce page requirements for mmap
  dt-bindings: usb: snps,dwc3: Fix "snps,hsphy_interface" type
  usb: gadget: udc: fix NULL dereference in remove()
  usb: gadget: f_fs: Add unbind event before functionfs_unbind
  usb: cdns3: fix NCM gadget RX speed 20x slow than expection at iMX8QM

2 files changed, 20 insertions, 1 deletions

diff --git a/Documentation/devicetree/bindings/usb/snps,dwc3.yaml b/Documentation/devicetree/bindings/usb/snps,dwc3.yaml
index 50edc4da780e..4f7625955ccc 100644
--- a/Documentation/devicetree/bindings/usb/snps,dwc3.yaml
+++ b/Documentation/devicetree/bindings/usb/snps,dwc3.yaml
@@ -287,7 +287,7 @@ properties:
     description:
       High-Speed PHY interface selection between UTMI+ and ULPI when the
       DWC_USB3_HSPHY_INTERFACE has value 3.
-    $ref: /schemas/types.yaml#/definitions/uint8
+    $ref: /schemas/types.yaml#/definitions/string
     enum: [utmi, ulpi]
 
   snps,quirk-frame-length-adjustment:
diff --git a/Documentation/mm/page_table_check.rst b/Documentation/mm/page_table_check.rst
index cfd8f4117cf3..c12838ce6b8d 100644
--- a/Documentation/mm/page_table_check.rst
+++ b/Documentation/mm/page_table_check.rst
@@ -52,3 +52,22 @@ Build kernel with:
 
 Optionally, build kernel with PAGE_TABLE_CHECK_ENFORCED in order to have page
 table support without extra kernel parameter.
+
+Implementation notes
+====================
+
+We specifically decided not to use VMA information in order to avoid relying on
+MM states (except for limited "struct page" info). The page table check is a
+separate from Linux-MM state machine that verifies that the user accessible
+pages are not falsely shared.
+
+PAGE_TABLE_CHECK depends on EXCLUSIVE_SYSTEM_RAM. The reason is that without
+EXCLUSIVE_SYSTEM_RAM, users are allowed to map arbitrary physical memory
+regions into the userspace via /dev/mem. At the same time, pages may change
+their properties (e.g., from anonymous pages to named pages) while they are
+still being mapped in the userspace, leading to "corruption" detected by the
+page table check.
+
+Even with EXCLUSIVE_SYSTEM_RAM, I/O pages may be still allowed to be mapped via
+/dev/mem. However, these pages are always considered as named pages, so they
+won't break the logic used in the page table check.