• Jason Lunz's avatar
    [PATCH] uml: fix LVM crash · af84eab2
    Jason Lunz authored
    Permit lvm to create logical volumes without crashing UML.
    
    When device-mapper's DM_DEV_CREATE_CMD ioctl is called to create a new device,
    dev_create()->dm_create()->alloc_dev()-> blk_queue_bounce_limit(md->queue,
    BLK_BOUNCE_ANY) is called.
    
    blk_queue_bounce_limit(BLK_BOUNCE_ANY) calls init_emergency_isa_pool() if
    blk_max_pfn < blk_max_low_pfn.  This is the case on UML, but
    init_emergency_isa_pool() hits BUG_ON(!isa_page_pool) because there doesn't
    seem to be a dma zone on UML for mempool_create() to allocate from.
    
    Most architectures seem to have max_low_pfn == max_pfn, but UML doesn't
    because of the uml_reserved chunk it keeps for itself.  From what I can see,
    max_pfn and max_low_pfn don't get much use after the bootmem-allocator stops
    being used anyway, except that they initialize the block layer's
    blk_max_low_pfn/blk_max_pfn.
    
    This ensures init_emergency_isa_pool() doesn't crash uml in this situation by
    setting max_low_pfn == max_pfn in mem_init().
    Signed-off-by: default avatarJason Lunz <lunz@falooley.org>
    Signed-off-by: default avatarJeff Dike <jdike@linux.intel.com>
    Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
    Cc: Alasdair G Kergon <agk@redhat.com>
    Cc: Jens Axboe <jens.axboe@oracle.com>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    af84eab2
mem.c 8.39 KB