From: David Hildenbrand <david@redhat.com>
To: Dan Williams <dan.j.williams@intel.com>, linux-mm@kvack.org
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>,
Andrew Morton <akpm@linux-foundation.org>,
vishal.l.verma@intel.com, linux-nvdimm@lists.01.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3 5/6] mm: Fix memory_failure() handling of dax-namespace metadata
Date: Wed, 13 Jan 2021 09:31:01 +0100 [thread overview]
Message-ID: <4664e9f3-5c2d-4c51-2bcd-9d03ef9c4fed@redhat.com> (raw)
In-Reply-To: <161052334425.1805594.17861842381807251887.stgit@dwillia2-desk3.amr.corp.intel.com>
On 13.01.21 08:35, 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 looking up by get_user_pages().
> I.e. metadata pfns are never user mapped.
>
> Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Reported-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(+)
>
> 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];
>
LGTM
Reviewed-by: David Hildenbrand <david@redhat.com>
--
Thanks,
David / dhildenb
next prev parent reply other threads:[~2021-01-13 8:32 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-13 7:35 [PATCH v3 0/6] mm: Fix pfn_to_online_page() with respect to ZONE_DEVICE Dan Williams
2021-01-13 7:35 ` [PATCH v3 1/6] mm: Move pfn_to_online_page() out of line Dan Williams
2021-01-13 7:35 ` [PATCH v3 2/6] mm: Teach pfn_to_online_page() to consider subsection validity Dan Williams
2021-01-13 8:29 ` David Hildenbrand
2021-01-13 21:52 ` Dan Williams
2021-01-13 8:30 ` Oscar Salvador
2021-01-13 7:35 ` [PATCH v3 3/6] mm: Teach pfn_to_online_page() about ZONE_DEVICE section collisions Dan Williams
2021-01-13 7:35 ` [PATCH v3 4/6] mm: Fix page reference leak in soft_offline_page() Dan Williams
2021-01-13 7:35 ` [PATCH v3 5/6] mm: Fix memory_failure() handling of dax-namespace metadata Dan Williams
2021-01-13 8:31 ` David Hildenbrand [this message]
2021-01-13 7:35 ` [PATCH v3 6/6] libnvdimm/namespace: Fix visibility of namespace resource attribute Dan Williams
2021-01-13 8:35 ` Greg KH
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