[PATCH v5 4/9] pmem,mm: Implement ->memory_failure in pmem driver

[Shiyang Ruan]

With dax_holder notify support, we are able to notify the memory failure
from pmem driver to upper layers.  If there is something not support in
the notify routine, memory_failure will fall back to the generic hanlder.

Signed-off-by: Shiyang Ruan <ruansy.fnst@xxxxxxxxxxx>
---
 drivers/nvdimm/pmem.c | 13 +++++++++++++
 mm/memory-failure.c   | 14 ++++++++++++++
 2 files changed, 27 insertions(+)

diff --git a/drivers/nvdimm/pmem.c b/drivers/nvdimm/pmem.c
index ed10a8b66068..95d79dfb2fc2 100644
--- a/drivers/nvdimm/pmem.c
+++ b/drivers/nvdimm/pmem.c
@@ -364,9 +364,22 @@ static void pmem_release_disk(void *__pmem)
 	put_disk(pmem->disk);
 }

+static int pmem_pagemap_memory_failure(struct dev_pagemap *pgmap,
+		unsigned long pfn, unsigned long nr_pfns, int flags)
+{
+	struct pmem_device *pmem =
+			container_of(pgmap, struct pmem_device, pgmap);
+	loff_t offset = PFN_PHYS(pfn) - pmem->phys_addr - pmem->data_offset;
+
+	return dax_holder_notify_failure(pmem->dax_dev, offset,
+					 page_size(pfn_to_page(pfn)) * nr_pfns,
+					 &flags);
+}
+
 static const struct dev_pagemap_ops fsdax_pagemap_ops = {
 	.kill			= pmem_pagemap_kill,
 	.cleanup		= pmem_pagemap_cleanup,
+	.memory_failure		= pmem_pagemap_memory_failure,
 };

 static int pmem_attach_disk(struct device *dev,
diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 068753911946..30ce1e653c0a 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -1411,6 +1411,20 @@ static int memory_failure_dev_pagemap(unsigned long pfn, int flags,
 	 */
 	SetPageHWPoison(page);

+	/*
+	 * Call driver's implementation to handle the memory failure, otherwise
+	 * fall back to generic handler.
+	 */
+	if (pgmap->ops->memory_failure) {
+		rc = pgmap->ops->memory_failure(pgmap, pfn, 1, flags);
+		/*
+		 * Fall back to generic handler too if operation is not
+		 * supported inside the driver/device/filesystem.
+		 */
+		if (rc != EOPNOTSUPP)
+			goto out;
+	}
+
 	mf_generic_kill_procs(pfn, flags);
 out:
 	/* drop pgmap ref acquired in caller */
--
2.32.0