From: Dan Williams <dan.j.williams@intel.com>
To: linux-mm@kvack.org
Cc: Qian Cai <cai@lca.pw>, Michal Hocko <mhocko@suse.com>,
David Hildenbrand <david@redhat.com>,
vishal.l.verma@intel.com, linux-nvdimm@lists.01.org,
linux-kernel@vger.kernel.org
Subject: [PATCH v2 2/5] mm: Teach pfn_to_online_page() to consider subsection validity
Date: Tue, 12 Jan 2021 01:34:47 -0800 [thread overview]
Message-ID: <161044408728.1482714.9086710868634042303.stgit@dwillia2-desk3.amr.corp.intel.com> (raw)
In-Reply-To: <161044407603.1482714.16630477578392768273.stgit@dwillia2-desk3.amr.corp.intel.com>
pfn_section_valid() determines pfn validity on subsection granularity.
pfn_valid_within() internally uses pfn_section_valid(), but gates it
with early_section() to preserve the traditional behavior of pfn_valid()
before subsection support was added.
pfn_to_online_page() wants the explicit precision that pfn_valid() does
not offer, so use pfn_section_valid() directly. Since
pfn_to_online_page() already open codes the validity of the section
number vs NR_MEM_SECTIONS, there's not much value to using
pfn_valid_within(), just use pfn_section_valid(). This loses the
valid_section() check that pfn_valid_within() was performing, but that
was already redundant with the online check.
Fixes: b13bc35193d9 ("mm/hotplug: invalid PFNs from pfn_to_online_page()")
Cc: Qian Cai <cai@lca.pw>
Cc: Michal Hocko <mhocko@suse.com>
Reported-by: David Hildenbrand <david@redhat.com>
---
mm/memory_hotplug.c | 16 ++++++++++++----
1 file changed, 12 insertions(+), 4 deletions(-)
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 55a69d4396e7..a845b3979bc0 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -308,11 +308,19 @@ static int check_hotplug_memory_addressable(unsigned long pfn,
struct page *pfn_to_online_page(unsigned long pfn)
{
unsigned long nr = pfn_to_section_nr(pfn);
+ struct mem_section *ms;
+
+ if (nr >= NR_MEM_SECTIONS)
+ return NULL;
+
+ ms = __nr_to_section(nr);
+ if (!online_section(ms))
+ return NULL;
+
+ if (!pfn_section_valid(ms, pfn))
+ return NULL;
- if (nr < NR_MEM_SECTIONS && online_section_nr(nr) &&
- pfn_valid_within(pfn))
- return pfn_to_page(pfn);
- return NULL;
+ return pfn_to_page(pfn);
}
EXPORT_SYMBOL_GPL(pfn_to_online_page);
next prev parent reply other threads:[~2021-01-12 9:35 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-12 9:34 [PATCH v2 0/5] mm: Fix pfn_to_online_page() with respect to ZONE_DEVICE Dan Williams
2021-01-12 9:34 ` [PATCH v2 1/5] mm: Move pfn_to_online_page() out of line Dan Williams
2021-01-12 9:46 ` David Hildenbrand
2021-01-12 10:19 ` Oscar Salvador
2021-01-12 9:34 ` Dan Williams [this message]
2021-01-12 9:53 ` [PATCH v2 2/5] mm: Teach pfn_to_online_page() to consider subsection validity David Hildenbrand
2021-01-12 10:48 ` Oscar Salvador
2021-01-12 22:20 ` Dan Williams
2021-01-12 9:34 ` [PATCH v2 3/5] mm: Teach pfn_to_online_page() about ZONE_DEVICE section collisions Dan Williams
2021-01-12 10:01 ` David Hildenbrand
2021-01-12 11:00 ` Oscar Salvador
2021-01-12 9:34 ` [PATCH v2 4/5] mm: Fix page reference leak in soft_offline_page() Dan Williams
2021-01-12 9:53 ` Oscar Salvador
2021-01-12 20:03 ` Dan Williams
2021-01-12 10:16 ` David Hildenbrand
2021-01-12 9:35 ` [PATCH v2 5/5] libnvdimm/namespace: Fix visibility of namespace resource attribute Dan Williams
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