Has this been reviewed properly? I do not see any Acks nor Reviewed-bys. Did Aneesh gave it some testing?
On Fri 18-10-19 20:19:33, Andrew Morton wrote: > From: David Hildenbrand <[email protected]> > 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/[email protected] > Fixes: f1dd2cd13c4b ("mm, memory_hotplug: do not associate hotadded memory to > zones until online") [d0dc12e86b319] > Signed-off-by: David Hildenbrand <[email protected]> > Reported-by: Aneesh Kumar K.V <[email protected]> > Cc: Oscar Salvador <[email protected]> > Cc: David Hildenbrand <[email protected]> > Cc: Michal Hocko <[email protected]> > Cc: Pavel Tatashin <[email protected]> > Cc: Dan Williams <[email protected]> > Cc: Wei Yang <[email protected]> > Cc: Alexander Duyck <[email protected]> > Cc: Alexander Potapenko <[email protected]> > Cc: Andy Lutomirski <[email protected]> > Cc: Anshuman Khandual <[email protected]> > Cc: Benjamin Herrenschmidt <[email protected]> > Cc: Borislav Petkov <[email protected]> > Cc: Catalin Marinas <[email protected]> > Cc: Christian Borntraeger <[email protected]> > Cc: Christophe Leroy <[email protected]> > Cc: Damian Tometzki <[email protected]> > Cc: Dave Hansen <[email protected]> > Cc: Fenghua Yu <[email protected]> > Cc: Gerald Schaefer <[email protected]> > Cc: Greg Kroah-Hartman <[email protected]> > Cc: Halil Pasic <[email protected]> > Cc: Heiko Carstens <[email protected]> > Cc: "H. Peter Anvin" <[email protected]> > Cc: Ingo Molnar <[email protected]> > Cc: Ira Weiny <[email protected]> > Cc: Jason Gunthorpe <[email protected]> > Cc: Jun Yao <[email protected]> > Cc: Logan Gunthorpe <[email protected]> > Cc: Mark Rutland <[email protected]> > Cc: Masahiro Yamada <[email protected]> > Cc: "Matthew Wilcox (Oracle)" <[email protected]> > Cc: Mel Gorman <[email protected]> > Cc: Michael Ellerman <[email protected]> > Cc: Mike Rapoport <[email protected]> > Cc: Pankaj Gupta <[email protected]> > Cc: Paul Mackerras <[email protected]> > Cc: Pavel Tatashin <[email protected]> > Cc: Peter Zijlstra <[email protected]> > Cc: Qian Cai <[email protected]> > Cc: Rich Felker <[email protected]> > Cc: Robin Murphy <[email protected]> > Cc: Steve Capper <[email protected]> > Cc: Thomas Gleixner <[email protected]> > Cc: Tom Lendacky <[email protected]> > Cc: Tony Luck <[email protected]> > Cc: Vasily Gorbik <[email protected]> > Cc: Vlastimil Babka <[email protected]> > Cc: Wei Yang <[email protected]> > Cc: Will Deacon <[email protected]> > Cc: Yoshinori Sato <[email protected]> > Cc: Yu Zhao <[email protected]> > Cc: <[email protected]> [4.13+] > Signed-off-by: Andrew Morton <[email protected]> > --- > > 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); > } > > _ -- Michal Hocko SUSE Labs
