[v4,5/5] mm: Fix memory_failure() handling of dax-namespace metadata
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Message ID 161058501758.1840162.4239831989762604527.stgit@dwillia2-desk3.amr.corp.intel.com
State In Next
Commit bd4e22b7bf23636549ea09c192bd6005e5341806
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Series
  • mm: Fix pfn_to_online_page() with respect to ZONE_DEVICE
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Commit Message

Dan Williams Jan. 14, 2021, 12:43 a.m. UTC
Given 'struct dev_pagemap' spans both data pages and metadata pages be
careful to consult the altmap if present to delineate metadata. In fact
the pfn_first() helper already identifies the first valid data pfn, so
export that helper for other code paths via pgmap_pfn_valid().

Other usage of get_dev_pagemap() are not a concern because those are
operating on known data pfns having been looked up by get_user_pages().
I.e. metadata pfns are never user mapped.

Fixes: 6100e34b2526 ("mm, memory_failure: Teach memory_failure() about dev_pagemap pages")
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Reported-by: David Hildenbrand <david@redhat.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
 include/linux/memremap.h |    6 ++++++
 mm/memory-failure.c      |    6 ++++++
 mm/memremap.c            |   15 +++++++++++++++
 3 files changed, 27 insertions(+)

Comments

HORIGUCHI NAOYA(堀口 直也) Jan. 14, 2021, 2:25 a.m. UTC | #1
On Wed, Jan 13, 2021 at 04:43:37PM -0800, Dan Williams wrote:
> Given 'struct dev_pagemap' spans both data pages and metadata pages be
> careful to consult the altmap if present to delineate metadata. In fact
> the pfn_first() helper already identifies the first valid data pfn, so
> export that helper for other code paths via pgmap_pfn_valid().
> 
> Other usage of get_dev_pagemap() are not a concern because those are
> operating on known data pfns having been looked up by get_user_pages().
> I.e. metadata pfns are never user mapped.
> 
> Fixes: 6100e34b2526 ("mm, memory_failure: Teach memory_failure() about dev_pagemap pages")
> Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Reported-by: David Hildenbrand <david@redhat.com>
> Reviewed-by: David Hildenbrand <david@redhat.com>
> Signed-off-by: Dan Williams <dan.j.williams@intel.com>

Looks fine to me.

Reviewed-by: Naoya Horiguchi <naoya.horiguchi@nec.com>

Patch
diff mbox series

diff --git a/include/linux/memremap.h b/include/linux/memremap.h
index 79c49e7f5c30..f5b464daeeca 100644
--- a/include/linux/memremap.h
+++ b/include/linux/memremap.h
@@ -137,6 +137,7 @@  void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap);
 void devm_memunmap_pages(struct device *dev, struct dev_pagemap *pgmap);
 struct dev_pagemap *get_dev_pagemap(unsigned long pfn,
 		struct dev_pagemap *pgmap);
+bool pgmap_pfn_valid(struct dev_pagemap *pgmap, unsigned long pfn);
 
 unsigned long vmem_altmap_offset(struct vmem_altmap *altmap);
 void vmem_altmap_free(struct vmem_altmap *altmap, unsigned long nr_pfns);
@@ -165,6 +166,11 @@  static inline struct dev_pagemap *get_dev_pagemap(unsigned long pfn,
 	return NULL;
 }
 
+static inline bool pgmap_pfn_valid(struct dev_pagemap *pgmap, unsigned long pfn)
+{
+	return false;
+}
+
 static inline unsigned long vmem_altmap_offset(struct vmem_altmap *altmap)
 {
 	return 0;
diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 78b173c7190c..541569cb4a99 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -1308,6 +1308,12 @@  static int memory_failure_dev_pagemap(unsigned long pfn, int flags,
 		 */
 		put_page(page);
 
+	/* device metadata space is not recoverable */
+	if (!pgmap_pfn_valid(pgmap, pfn)) {
+		rc = -ENXIO;
+		goto out;
+	}
+
 	/*
 	 * Prevent the inode from being freed while we are interrogating
 	 * the address_space, typically this would be handled by
diff --git a/mm/memremap.c b/mm/memremap.c
index 16b2fb482da1..2455bac89506 100644
--- a/mm/memremap.c
+++ b/mm/memremap.c
@@ -80,6 +80,21 @@  static unsigned long pfn_first(struct dev_pagemap *pgmap, int range_id)
 	return pfn + vmem_altmap_offset(pgmap_altmap(pgmap));
 }
 
+bool pgmap_pfn_valid(struct dev_pagemap *pgmap, unsigned long pfn)
+{
+	int i;
+
+	for (i = 0; i < pgmap->nr_range; i++) {
+		struct range *range = &pgmap->ranges[i];
+
+		if (pfn >= PHYS_PFN(range->start) &&
+		    pfn <= PHYS_PFN(range->end))
+			return pfn >= pfn_first(pgmap, i);
+	}
+
+	return false;
+}
+
 static unsigned long pfn_end(struct dev_pagemap *pgmap, int range_id)
 {
 	const struct range *range = &pgmap->ranges[range_id];