From: David Hildenbrand <david@xxxxxxxxxx>
Subject: 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@xxxxxxxxxx
Fixes: f1dd2cd13c4b ("mm, memory_hotplug: do not associate hotadded memory to zones until online") [d0dc12e86b319]
Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>
Reported-by: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxx>
Cc: Oscar Salvador <osalvador@xxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Pavel Tatashin <pasha.tatashin@xxxxxxxxxx>
Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
Cc: Wei Yang <richardw.yang@xxxxxxxxxxxxxxx>
Cc: Alexander Duyck <alexander.h.duyck@xxxxxxxxxxxxxxx>
Cc: Alexander Potapenko <glider@xxxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: Anshuman Khandual <anshuman.khandual@xxxxxxx>
Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Christian Borntraeger <borntraeger@xxxxxxxxxx>
Cc: Christophe Leroy <christophe.leroy@xxxxxx>
Cc: Damian Tometzki <damian.tometzki@xxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Cc: Fenghua Yu <fenghua.yu@xxxxxxxxx>
Cc: Gerald Schaefer <gerald.schaefer@xxxxxxxxxx>
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: Halil Pasic <pasic@xxxxxxxxxxxxx>
Cc: Heiko Carstens <heiko.carstens@xxxxxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Ira Weiny <ira.weiny@xxxxxxxxx>
Cc: Jason Gunthorpe <jgg@xxxxxxxx>
Cc: Jun Yao <yaojun8558363@xxxxxxxxx>
Cc: Logan Gunthorpe <logang@xxxxxxxxxxxx>
Cc: Mark Rutland <mark.rutland@xxxxxxx>
Cc: Masahiro Yamada <yamada.masahiro@xxxxxxxxxxxxx>
Cc: "Matthew Wilcox (Oracle)" <willy@xxxxxxxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Cc: Mike Rapoport <rppt@xxxxxxxxxxxxx>
Cc: Pankaj Gupta <pagupta@xxxxxxxxxx>
Cc: Paul Mackerras <paulus@xxxxxxxxx>
Cc: Pavel Tatashin <pavel.tatashin@xxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Qian Cai <cai@xxxxxx>
Cc: Rich Felker <dalias@xxxxxxxx>
Cc: Robin Murphy <robin.murphy@xxxxxxx>
Cc: Steve Capper <steve.capper@xxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Tom Lendacky <thomas.lendacky@xxxxxxx>
Cc: Tony Luck <tony.luck@xxxxxxxxx>
Cc: Vasily Gorbik <gor@xxxxxxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Cc: Wei Yang <richard.weiyang@xxxxxxxxx>
Cc: Will Deacon <will@xxxxxxxxxx>
Cc: Yoshinori Sato <ysato@xxxxxxxxxxxxxxxxxxxx>
Cc: Yu Zhao <yuzhao@xxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx> [4.13+]
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/memory_hotplug.c | 74 +++++++++---------------------------------
1 file changed, 16 insertions(+), 58 deletions(-)
--- a/mm/memory_hotplug.c~mm-memory_hotplug-dont-access-uninitialized-memmaps-in-shrink_pgdat_span
+++ a/mm/memory_hotplug.c
@@ -436,67 +436,25 @@ static void shrink_zone_span(struct zone
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;
-
- /* Skip range to be removed */
- if (pfn >= start_pfn && pfn < end_pfn)
- continue;
+ unsigned long node_start_pfn = 0, node_end_pfn = 0;
+ struct zone *zone;
- /* If we find valid section, we have nothing to do */
- return;
+ 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;
+
+ /* 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 *z
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);
}
_
