• Andy Whitcroft's avatar
    zonelists: handle a node zonelist with no applicable entries · 7eb54824
    Andy Whitcroft authored
    When booting 2.6.26-rc3 on a multi-node x86_32 numa system we are seeing
    panics when trying node local allocations:
    
     BUG: unable to handle kernel NULL pointer dereference at 0000034c
     IP: [<c1042507>] get_page_from_freelist+0x4a/0x18e
     *pdpt = 00000000013a7001 *pde = 0000000000000000
     Oops: 0000 [#1] SMP
     Modules linked in:
    
     Pid: 0, comm: swapper Not tainted (2.6.26-rc3-00003-g5abc28d #82)
     EIP: 0060:[<c1042507>] EFLAGS: 00010282 CPU: 0
     EIP is at get_page_from_freelist+0x4a/0x18e
     EAX: c1371ed8 EBX: 00000000 ECX: 00000000 EDX: 00000000
     ESI: f7801180 EDI: 00000000 EBP: 00000000 ESP: c1371ec0
      DS: 007b ES: 007b FS: 00d8 GS: 0000 SS: 0068
     Process swapper (pid: 0, ti=c1370000 task=c12f5b40 task.ti=c1370000)
     Stack: 00000000 00000000 00000000 00000000 000612d0 000412d0 00000000 000412d0
            f7801180 f7c0101c f7c01018 c10426e4 f7c01018 00000001 00000044 00000000
            00000001 c12f5b40 00000001 00000010 00000000 000412d0 00000286 000412d0
     Call Trace:
      [<c10426e4>] __alloc_pages_internal+0x99/0x378
      [<c10429ca>] __alloc_pages+0x7/0x9
      [<c105e0e8>] kmem_getpages+0x66/0xef
      [<c105ec55>] cache_grow+0x8f/0x123
      [<c105f117>] ____cache_alloc_node+0xb9/0xe4
      [<c105f427>] kmem_cache_alloc_node+0x92/0xd2
      [<c122118c>] setup_cpu_cache+0xaf/0x177
      [<c105e6ca>] kmem_cache_create+0x2c8/0x353
      [<c13853af>] kmem_cache_init+0x1ce/0x3ad
      [<c13755c5>] start_kernel+0x178/0x1ee
    
    This occurs when we are scanning the zonelists looking for a ZONE_NORMAL
    page.  In this system there is only ZONE_DMA and ZONE_NORMAL memory on
    node 0, all other nodes are mapped above 4GB physical.  Here is a dump
    of the zonelists from this system:
    
        zonelists pgdat=c1400000
         0: c14006c0:2 f7c006c0:2 f7e006c0:2 c1400360:1 c1400000:0
         1: c14006c0:2 c1400360:1 c1400000:0
        zonelists pgdat=f7c00000
         0: f7c006c0:2 f7e006c0:2 c14006c0:2 c1400360:1 c1400000:0
         1: f7c006c0:2
        zonelists pgdat=f7e00000
         0: f7e006c0:2 c14006c0:2 f7c006c0:2 c1400360:1 c1400000:0
         1: f7e006c0:2
    
    When performing a node local allocation we call get_page_from_freelist()
    looking for a page.  It in turn calls first_zones_zonelist() which returns
    a preferred_zone.  Where there are no applicable zones this will be NULL.
    However we use this unconditionally, leading to this panic.
    
    Where there are no applicable zones there is no possibility of a successful
    allocation, so simply fail the allocation.
    Signed-off-by: default avatarAndy Whitcroft <apw@shadowen.org>
    Acked-by: default avatarMel Gorman <mel@csn.ul.ie>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    7eb54824
page_alloc.c 126 KB