• Aneesh Kumar K.V's avatar
    mm/memunmap: don't access uninitialized memmap in memunmap_pages() · 77e080e7
    Aneesh Kumar K.V authored
    Patch series "mm/memory_hotplug: Shrink zones before removing memory",
    v6.
    
    This series fixes the access of uninitialized memmaps when shrinking
    zones/nodes and when removing memory.  Also, it contains all fixes for
    crashes that can be triggered when removing certain namespace using
    memunmap_pages() - ZONE_DEVICE, reported by Aneesh.
    
    We stop trying to shrink ZONE_DEVICE, as it's buggy, fixing it would be
    more involved (we don't have SECTION_IS_ONLINE as an indicator), and
    shrinking is only of limited use (set_zone_contiguous() cannot detect
    the ZONE_DEVICE as contiguous).
    
    We continue shrinking !ZONE_DEVICE zones, however, I reduced the amount
    of code to a minimum.  Shrinking is especially necessary to keep
    zone->contiguous set where possible, especially, on memory unplug of
    DIMMs at zone boundaries.
    
    --------------------------------------------------------------------------
    
    Zones are now properly shrunk when offlining memory blocks or when
    onlining failed.  This allows to properly shrink zones on memory unplug
    even if the separate memory blocks of a DIMM were onlined to different
    zones or re-onlined to a different zone after offlining.
    
    Example:
    
      :/# cat /proc/zoneinfo
      Node 1, zone  Movable
              spanned  0
              present  0
              managed  0
      :/# echo "online_movable" > /sys/devices/system/memory/memory41/state
      :/# echo "online_movable" > /sys/devices/system/memory/memory43/state
      :/# cat /proc/zoneinfo
      Node 1, zone  Movable
              spanned  98304
              present  65536
              managed  65536
      :/# echo 0 > /sys/devices/system/memory/memory43/online
      :/# cat /proc/zoneinfo
      Node 1, zone  Movable
              spanned  32768
              present  32768
              managed  32768
      :/# echo 0 > /sys/devices/system/memory/memory41/online
      :/# cat /proc/zoneinfo
      Node 1, zone  Movable
              spanned  0
              present  0
              managed  0
    
    This patch (of 10):
    
    With an altmap, the memmap falling into the reserved altmap space are not
    initialized and, therefore, contain a garbage NID and a garbage zone.
    Make sure to read the NID/zone from a memmap that was initialized.
    
    This fixes a kernel crash that is observed when destroying a namespace:
    
      kernel BUG at include/linux/mm.h:1107!
      cpu 0x1: Vector: 700 (Program Check) at [c000000274087890]
          pc: c0000000004b9728: memunmap_pages+0x238/0x340
          lr: c0000000004b9724: memunmap_pages+0x234/0x340
      ...
          pid   = 3669, comm = ndctl
      kernel BUG at include/linux/mm.h:1107!
        devm_action_release+0x30/0x50
        release_nodes+0x268/0x2d0
        device_release_driver_internal+0x174/0x240
        unbind_store+0x13c/0x190
        drv_attr_store+0x44/0x60
        sysfs_kf_write+0x70/0xa0
        kernfs_fop_write+0x1ac/0x290
        __vfs_write+0x3c/0x70
        vfs_write+0xe4/0x200
        ksys_write+0x7c/0x140
        system_call+0x5c/0x68
    
    The "page_zone(pfn_to_page(pfn)" was introduced by 69324b8f ("mm,
    devm_memremap_pages: add MEMORY_DEVICE_PRIVATE support"), however, I
    think we will never have driver reserved memory with
    MEMORY_DEVICE_PRIVATE (no altmap AFAIKS).
    
    [david@redhat.com: minimze code changes, rephrase description]
    Link: http://lkml.kernel.org/r/20191006085646.5768-2-david@redhat.com
    Fixes: 2c2a5af6 ("mm, memory_hotplug: add nid parameter to arch_remove_memory")
    Signed-off-by: default avatarAneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
    Signed-off-by: default avatarDavid Hildenbrand <david@redhat.com>
    Cc: Dan Williams <dan.j.williams@intel.com>
    Cc: Jason Gunthorpe <jgg@ziepe.ca>
    Cc: Logan Gunthorpe <logang@deltatee.com>
    Cc: Ira Weiny <ira.weiny@intel.com>
    Cc: Damian Tometzki <damian.tometzki@gmail.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: 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: Jun Yao <yaojun8558363@gmail.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: Michal Hocko <mhocko@suse.com>
    Cc: Mike Rapoport <rppt@linux.ibm.com>
    Cc: Oscar Salvador <osalvador@suse.de>
    Cc: Pankaj Gupta <pagupta@redhat.com>
    Cc: Paul Mackerras <paulus@samba.org>
    Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
    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: Wei Yang <richardw.yang@linux.intel.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>	[5.0+]
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    77e080e7
memremap.c 12.2 KB