Commit 34dc45be authored by Dan Williams's avatar Dan Williams Committed by Linus Torvalds
Browse files

mm: fix memory_failure() handling of dax-namespace metadata 

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.

Link: https://lkml.kernel.org/r/161058501758.1840162.4239831989762604527.stgit@dwillia2-desk3.amr.corp.intel.com


Fixes: 6100e34b ("mm, memory_failure: Teach memory_failure() about dev_pagemap pages")
Signed-off-by: default avatarDan Williams <dan.j.williams@intel.com>
Reported-by: default avatarDavid Hildenbrand <david@redhat.com>
Reviewed-by: default avatarDavid Hildenbrand <david@redhat.com>
Reviewed-by: default avatarNaoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Qian Cai <cai@lca.pw>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 1f90a347

include/linux/memremap.h

+6 −0
Original line number Diff line number Diff line
@@ -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;

mm/memory-failure.c

+6 −0
Original line number Diff line number Diff line
@@ -1312,6 +1312,12 @@ 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

mm/memremap.c

+15 −0
Original line number Diff line number Diff line
@@ -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];