FAILED: patch "[PATCH] mm/memory_hotplug: don't access uninitialized memmaps in" failed to apply to 4.14-stable tree - Linux-stable-mirror

27 Oct 2019

The patch below does not apply to the 4.14-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to stable@vger.kernel.org.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
...
From 00d6c019b5bc175cee3770e0e659f2b5f4804ea5 Mon Sep 17 00:00:00 2001
From: David Hildenbrand david@redhat.com
Date: Fri, 18 Oct 2019 20:19:33 -0700
Subject: [PATCH] mm/memory_hotplug: don't access uninitialized memmaps in
 shrink_pgdat_span()
We might use the nid of memmaps that were never initialized.  For
example, if the memmap was poisoned, we will crash the kernel in
pfn_to_nid() right now.  Let's use the calculated boundaries of the
separate zones instead.  This now also avoids having to iterate over a
whole bunch of subsections again, after shrinking one zone.
Before commit d0dc12e86b31 ("mm/memory_hotplug: optimize memory
hotplug"), the memmap was initialized to 0 and the node was set to the
right value.  After that commit, the node might be garbage.
We'll have to fix shrink_zone_span() next.
Link: http://lkml.kernel.org/r/20191006085646.5768-4-david@redhat.com
Fixes: f1dd2cd13c4b ("mm, memory_hotplug: do not associate hotadded memory to zones until online")	[d0dc12e86b319]
Signed-off-by: David Hildenbrand david@redhat.com
Reported-by: Aneesh Kumar K.V aneesh.kumar@linux.ibm.com
Cc: Oscar Salvador osalvador@suse.de
Cc: David Hildenbrand david@redhat.com
Cc: Michal Hocko mhocko@suse.com
Cc: Pavel Tatashin pasha.tatashin@soleen.com
Cc: Dan Williams dan.j.williams@intel.com
Cc: Wei Yang richardw.yang@linux.intel.com
Cc: Alexander Duyck alexander.h.duyck@linux.intel.com
Cc: Alexander Potapenko glider@google.com
Cc: Andy Lutomirski luto@kernel.org
Cc: Anshuman Khandual anshuman.khandual@arm.com
Cc: Benjamin Herrenschmidt benh@kernel.crashing.org
Cc: Borislav Petkov bp@alien8.de
Cc: Catalin Marinas catalin.marinas@arm.com
Cc: Christian Borntraeger borntraeger@de.ibm.com
Cc: Christophe Leroy christophe.leroy@c-s.fr
Cc: Damian Tometzki damian.tometzki@gmail.com
Cc: Dave Hansen dave.hansen@linux.intel.com
Cc: Fenghua Yu fenghua.yu@intel.com
Cc: Gerald Schaefer gerald.schaefer@de.ibm.com
Cc: Greg Kroah-Hartman gregkh@linuxfoundation.org
Cc: Halil Pasic pasic@linux.ibm.com
Cc: Heiko Carstens heiko.carstens@de.ibm.com
Cc: "H. Peter Anvin" hpa@zytor.com
Cc: Ingo Molnar mingo@redhat.com
Cc: Ira Weiny ira.weiny@intel.com
Cc: Jason Gunthorpe jgg@ziepe.ca
Cc: Jun Yao yaojun8558363@gmail.com
Cc: Logan Gunthorpe logang@deltatee.com
Cc: Mark Rutland mark.rutland@arm.com
Cc: Masahiro Yamada yamada.masahiro@socionext.com
Cc: "Matthew Wilcox (Oracle)" willy@infradead.org
Cc: Mel Gorman mgorman@techsingularity.net
Cc: Michael Ellerman mpe@ellerman.id.au
Cc: Mike Rapoport rppt@linux.ibm.com
Cc: Pankaj Gupta pagupta@redhat.com
Cc: Paul Mackerras paulus@samba.org
Cc: Pavel Tatashin pavel.tatashin@microsoft.com
Cc: Peter Zijlstra peterz@infradead.org
Cc: Qian Cai cai@lca.pw
Cc: Rich Felker dalias@libc.org
Cc: Robin Murphy robin.murphy@arm.com
Cc: Steve Capper steve.capper@arm.com
Cc: Thomas Gleixner tglx@linutronix.de
Cc: Tom Lendacky thomas.lendacky@amd.com
Cc: Tony Luck tony.luck@intel.com
Cc: Vasily Gorbik gor@linux.ibm.com
Cc: Vlastimil Babka vbabka@suse.cz
Cc: Wei Yang richard.weiyang@gmail.com
Cc: Will Deacon will@kernel.org
Cc: Yoshinori Sato ysato@users.sourceforge.jp
Cc: Yu Zhao yuzhao@google.com
Cc: stable@vger.kernel.org	[4.13+]
Signed-off-by: Andrew Morton akpm@linux-foundation.org
Signed-off-by: Linus Torvalds torvalds@linux-foundation.org

diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index b1be791f772d..df570e5c71cc 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -436,67 +436,25 @@ static void shrink_zone_span(struct zone *zone, unsigned long start_pfn,
    zone_span_writeunlock(zone);
 }
-static void shrink_pgdat_span(struct pglist_data *pgdat,
-			      unsigned long start_pfn, unsigned long end_pfn)
+static void update_pgdat_span(struct pglist_data *pgdat)
 {
-	unsigned long pgdat_start_pfn = pgdat->node_start_pfn;
-	unsigned long p = pgdat_end_pfn(pgdat); /* pgdat_end_pfn namespace clash */
-	unsigned long pgdat_end_pfn = p;
-	unsigned long pfn;
-	int nid = pgdat->node_id;
-
-	if (pgdat_start_pfn == start_pfn) {
-		/*
-		 * If the section is smallest section in the pgdat, it need
-		 * shrink pgdat->node_start_pfn and pgdat->node_spanned_pages.
-		 * In this case, we find second smallest valid mem_section
-		 * for shrinking zone.
-		 */
-		pfn = find_smallest_section_pfn(nid, NULL, end_pfn,
-						pgdat_end_pfn);
-		if (pfn) {
-			pgdat->node_start_pfn = pfn;
-			pgdat->node_spanned_pages = pgdat_end_pfn - pfn;
-		}
-	} else if (pgdat_end_pfn == end_pfn) {
-		/*
-		 * If the section is biggest section in the pgdat, it need
-		 * shrink pgdat->node_spanned_pages.
-		 * In this case, we find second biggest valid mem_section for
-		 * shrinking zone.
-		 */
-		pfn = find_biggest_section_pfn(nid, NULL, pgdat_start_pfn,
-					       start_pfn);
-		if (pfn)
-			pgdat->node_spanned_pages = pfn - pgdat_start_pfn + 1;
-	}
-
-	/*
-	 * If the section is not biggest or smallest mem_section in the pgdat,
-	 * it only creates a hole in the pgdat. So in this case, we need not
-	 * change the pgdat.
-	 * But perhaps, the pgdat has only hole data. Thus it check the pgdat
-	 * has only hole or not.
-	 */
-	pfn = pgdat_start_pfn;
-	for (; pfn < pgdat_end_pfn; pfn += PAGES_PER_SUBSECTION) {
-		if (unlikely(!pfn_valid(pfn)))
-			continue;
-
-		if (pfn_to_nid(pfn) != nid)
-			continue;
+	unsigned long node_start_pfn = 0, node_end_pfn = 0;
+	struct zone *zone;
-		/* Skip range to be removed */
-		if (pfn >= start_pfn && pfn < end_pfn)
-			continue;
+	for (zone = pgdat->node_zones;
+	     zone < pgdat->node_zones + MAX_NR_ZONES; zone++) {
+		unsigned long zone_end_pfn = zone->zone_start_pfn +
+					     zone->spanned_pages;
-		/* If we find valid section, we have nothing to do */
-		return;
+		/* No need to lock the zones, they can't change. */
+		if (zone_end_pfn > node_end_pfn)
+			node_end_pfn = zone_end_pfn;
+		if (zone->zone_start_pfn < node_start_pfn)
+			node_start_pfn = zone->zone_start_pfn;
    }
-	/* The pgdat has no valid section */
-	pgdat->node_start_pfn = 0;
-	pgdat->node_spanned_pages = 0;
+	pgdat->node_start_pfn = node_start_pfn;
+	pgdat->node_spanned_pages = node_end_pfn - node_start_pfn;
 }
static void __remove_zone(struct zone *zone, unsigned long start_pfn,
@@ -507,7 +465,7 @@ static void __remove_zone(struct zone *zone, unsigned long start_pfn,
pgdat_resize_lock(zone->zone_pgdat, &flags);
    shrink_zone_span(zone, start_pfn, start_pfn + nr_pages);
-	shrink_pgdat_span(pgdat, start_pfn, start_pfn + nr_pages);
+	update_pgdat_span(pgdat);
    pgdat_resize_unlock(zone->zone_pgdat, &flags);
 }

    