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From: Dan Williams <dan.j.williams@intel.com>
To: linux-mm@kvack.org
Cc: Qian Cai <cai@lca.pw>, Michal Hocko <mhocko@suse.com>,
	Oscar Salvador <osalvador@suse.de>,
	David Hildenbrand <david@redhat.com>,
	vishal.l.verma@intel.com, linux-nvdimm@lists.01.org,
	linux-kernel@vger.kernel.org
Subject: [PATCH v3 2/6] mm: Teach pfn_to_online_page() to consider subsection validity
Date: Tue, 12 Jan 2021 23:35:27 -0800	[thread overview]
Message-ID: <161052332755.1805594.9846390935351758277.stgit@dwillia2-desk3.amr.corp.intel.com> (raw)
In-Reply-To: <161052331545.1805594.2356512831689786960.stgit@dwillia2-desk3.amr.corp.intel.com>

pfn_section_valid() determines pfn validity on subsection granularity
where pfn_valid() may be limited to coarse section granularity.
Explicitly validate subsections after pfn_valid() succeeds.

Fixes: b13bc35193d9 ("mm/hotplug: invalid PFNs from pfn_to_online_page()")
Cc: Qian Cai <cai@lca.pw>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Oscar Salvador <osalvador@suse.de>
Reported-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
 mm/memory_hotplug.c |   24 ++++++++++++++++++++----
 1 file changed, 20 insertions(+), 4 deletions(-)

diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 55a69d4396e7..9f37f8a68da4 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -308,11 +308,27 @@ 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;
+
+	/*
+	 * Save some code text when online_section() +
+	 * pfn_section_valid() are sufficient.
+	 */
+	if (IS_ENABLED(CONFIG_HAVE_ARCH_PFN_VALID))
+		if (!pfn_valid(pfn))
+			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);
 


  parent reply	other threads:[~2021-01-13  7:36 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 ` Dan Williams [this message]
2021-01-13  8:29   ` [PATCH v3 2/6] mm: Teach pfn_to_online_page() to consider subsection validity 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
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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