On 27.10.19 14:43, gregkh@linuxfoundation.org wrote:
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); }
We'll come back to this once we sorted out
https://lkml.org/lkml/2019/10/27/738