[PATCH v4 05/10] mm, pmem: Implement ->memory_failure() in pmem driver

Shiyang Ruan
2021-06-04T01:19:17Z

Call the ->memory_failure() which is implemented by pmem driver, in
order to finally notify filesystem to handle the corrupted data. The
handler which collects and kills processes are moved into
mf_dax_kill_procs(), which will be called by filesystem.

Keep the old handler in order to roll back if driver or filesystem
does not support ->memory_failure()/->corrupted_range().

Signed-off-by: Shiyang Ruan <ruansy.fnst@fujitsu.com>
---
block/genhd.c | 30 ++++++++++++++++++
drivers/nvdimm/pmem.c | 14 +++++++++
include/linux/genhd.h | 1 +
mm/memory-failure.c | 71 +++++++++++++++++++++++++++----------------
4 files changed, 90 insertions(+), 26 deletions(-)

diff --git a/block/genhd.c b/block/genhd.c
index 9f8cb7beaad1..75834bd057df 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -718,6 +718,36 @@ struct block_device *bdget_disk(struct gendisk *disk, int partno)
return bdev;
}

+/**
+ * bdget_disk_sector - get block device by given sector number
+ * @disk: gendisk of interest
+ * @sector: sector number
+ *
+ * RETURNS: the found block device where sector locates in
+ */
+struct block_device *bdget_disk_sector(struct gendisk *disk, sector_t sector)
+{
+ struct block_device *part = NULL, *p;
+ unsigned long idx;
+
+ rcu_read_lock();
+ xa_for_each(&disk->part_tbl, idx, p) {
+ if (p->bd_partno == 0)
+ continue;
+ if (p->bd_start_sect <= sector &&
+ sector < p->bd_start_sect + bdev_nr_sectors(p)) {
+ part = p;
+ break;
+ }
+ }
+ rcu_read_unlock();
+ if (!part)
+ part = disk->part0;
+
+ return bdget_disk(disk, part->bd_partno);
+}
+EXPORT_SYMBOL(bdget_disk_sector);
+
/*
* print a full list of all partitions - intended for places where the root
* filesystem can't be mounted and thus to give the victim some idea of what
diff --git a/drivers/nvdimm/pmem.c b/drivers/nvdimm/pmem.c
index ed10a8b66068..98349e7d0a28 100644
--- a/drivers/nvdimm/pmem.c
+++ b/drivers/nvdimm/pmem.c
@@ -364,9 +364,23 @@ static void pmem_release_disk(void *__pmem)
put_disk(pmem->disk);
}

+static int pmem_pagemap_memory_failure(struct dev_pagemap *pgmap,
+ unsigned long pfn, int flags)
+{
+ struct pmem_device *pdev =
+ container_of(pgmap, struct pmem_device, pgmap);
+ loff_t offset = PFN_PHYS(pfn) - pdev->phys_addr - pdev->data_offset;
+ struct block_device *bdev =
+ bdget_disk_sector(pdev->disk, offset >> SECTOR_SHIFT);
+
+ return dax_corrupted_range(pdev->dax_dev, bdev, offset,
+ page_size(pfn_to_page(pfn)), &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/include/linux/genhd.h b/include/linux/genhd.h
index 6fc26f7bdf71..2ad70c02c343 100644
--- a/include/linux/genhd.h
+++ b/include/linux/genhd.h
@@ -219,6 +219,7 @@ static inline void add_disk_no_queue_reg(struct gendisk *disk)

extern void del_gendisk(struct gendisk *gp);
extern struct block_device *bdget_disk(struct gendisk *disk, int partno);
+extern struct block_device *bdget_disk_sector(struct gendisk *disk, sector_t sector);

void set_disk_ro(struct gendisk *disk, bool read_only);

diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 4377e727d478..43017d7f3918 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -1247,6 +1247,36 @@ static void unmap_and_kill(struct list_head *to_kill, unsigned long pfn,
kill_procs(to_kill, flags & MF_MUST_KILL, false, pfn, flags);
}

+static int mf_generic_kill_procs(unsigned long long pfn, int flags)
+{
+ struct page *page = pfn_to_page(pfn);
+ LIST_HEAD(to_kill);
+ dax_entry_t cookie;
+
+ /*
+ * Prevent the inode from being freed while we are interrogating
+ * the address_space, typically this would be handled by
+ * lock_page(), but dax pages do not use the page lock. This
+ * also prevents changes to the mapping of this pfn until
+ * poison signaling is complete.
+ */
+ cookie = dax_lock_page(page);
+ if (!cookie)
+ return -EBUSY;
+ /*
+ * Unlike System-RAM there is no possibility to swap in a
+ * different physical page at a given virtual address, so all
+ * userspace consumption of ZONE_DEVICE memory necessitates
+ * SIGBUS (i.e. MF_MUST_KILL)
+ */
+ flags |= MF_ACTION_REQUIRED | MF_MUST_KILL;
+ collect_procs(page, &to_kill, flags & MF_ACTION_REQUIRED);
+
+ unmap_and_kill(&to_kill, pfn, page->mapping, page->index, flags);
+ dax_unlock_page(page, cookie);
+ return 0;
+}
+
int mf_dax_kill_procs(struct address_space *mapping, pgoff_t index, int flags)
{
LIST_HEAD(to_kill);
@@ -1348,9 +1378,7 @@ static int memory_failure_dev_pagemap(unsigned long pfn, int flags,
struct dev_pagemap *pgmap)
{
struct page *page = pfn_to_page(pfn);
- LIST_HEAD(to_kill);
int rc = -EBUSY;
- dax_entry_t cookie;

if (flags & MF_COUNT_INCREASED)
/*
@@ -1364,20 +1392,9 @@ static int memory_failure_dev_pagemap(unsigned long pfn, int flags,
goto out;
}

- /*
- * Prevent the inode from being freed while we are interrogating
- * the address_space, typically this would be handled by
- * lock_page(), but dax pages do not use the page lock. This
- * also prevents changes to the mapping of this pfn until
- * poison signaling is complete.
- */
- cookie = dax_lock_page(page);
- if (!cookie)
- goto out;
-
if (hwpoison_filter(page)) {
rc = 0;
- goto unlock;
+ goto out;
}

if (pgmap->type == MEMORY_DEVICE_PRIVATE) {
@@ -1385,7 +1402,7 @@ static int memory_failure_dev_pagemap(unsigned long pfn, int flags,
* TODO: Handle HMM pages which may need coordination
* with device-side memory.
*/
- goto unlock;
+ goto out;
}

/*
@@ -1395,19 +1412,21 @@ static int memory_failure_dev_pagemap(unsigned long pfn, int flags,
SetPageHWPoison(page);

/*
- * Unlike System-RAM there is no possibility to swap in a
- * different physical page at a given virtual address, so all
- * userspace consumption of ZONE_DEVICE memory necessitates
- * SIGBUS (i.e. MF_MUST_KILL)
+ * Call driver's implementation to handle the memory failure,
+ * otherwise roll back to generic handler.
*/
- flags |= MF_ACTION_REQUIRED | MF_MUST_KILL;
- collect_procs_file(page, page->mapping, page->index, &to_kill,
- flags & MF_ACTION_REQUIRED);
+ if (pgmap->ops->memory_failure) {
+ rc = pgmap->ops->memory_failure(pgmap, pfn, flags);
+ /*
+ * Roll back to generic handler too if operation is not
+ * supported inside the driver/device/filesystem.
+ */
+ if (rc != EOPNOTSUPP)
+ goto out;
+ }
+
+ rc = mf_generic_kill_procs(pfn, flags);

- unmap_and_kill(&to_kill, pfn, page->mapping, page->index, flags);
- rc = 0;
-unlock:
- dax_unlock_page(page, cookie);
out:
/* drop pgmap ref acquired in caller */
put_dev_pagemap(pgmap);
--
2.31.1