Merge tag 'spi-nor/for-5.19' into mtd/next

SPI NOR core changes:
- Read back written SR value to make sure the write was done correctly.
- Introduce a common function for Read ID that manufacturer drivers can
  use to verify the Octal DTR switch worked correctly.
- Add helpers for read/write any register commands so manufacturer
  drivers don't open code it every time.
- Clarify rdsr dummy cycles documentation.
- Add debugfs entry to expose internal flash parameters and state.

SPI NOR manufacturer drivers changes:
- Add support for Winbond W25Q512NW-IM, and Eon EN25QH256A.
- Move spi_nor_write_ear() to Winbond module since only Winbond flashes
  use it.
- Rework Micron and Cypress Octal DTR enable methods to improve
  readability.
- Use the common Read ID function to verify switch to Octal DTR mode for
  Micron and Cypress flashes.
- Skip polling status on volatile register writes for Micron and Cypress
  flashes since the operation is instant.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>

1 files changed, 3 insertions, 0 deletions

diff --git a/mm/mremap.c b/mm/mremap.c
index 9d76da79594d..303d3290b938 100644
--- a/mm/mremap.c
+++ b/mm/mremap.c
@@ -486,6 +486,9 @@ unsigned long move_page_tables(struct vm_area_struct *vma,
 	pmd_t *old_pmd, *new_pmd;
 	pud_t *old_pud, *new_pud;
 
+	if (!len)
+		return 0;
+
 	old_end = old_addr + len;
 	flush_cache_range(vma, old_addr, old_end);