Gitweb:     
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=af84eab208916acad91f6342bbd57bc865caf150
Commit:     af84eab208916acad91f6342bbd57bc865caf150
Parent:     3076212f8d3d9fe4d7b11c6b560c0f424edfcb4e
Author:     Jason Lunz <[EMAIL PROTECTED]>
AuthorDate: Thu Mar 29 01:20:31 2007 -0700
Committer:  Linus Torvalds <[EMAIL PROTECTED]>
CommitDate: Thu Mar 29 08:22:24 2007 -0700

    [PATCH] uml: fix LVM crash
    
    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: Jason Lunz <[EMAIL PROTECTED]>
    Signed-off-by: Jeff Dike <[EMAIL PROTECTED]>
    Cc: Paolo 'Blaisorblade' Giarrusso <[EMAIL PROTECTED]>
    Cc: Alasdair G Kergon <[EMAIL PROTECTED]>
    Cc: Jens Axboe <[EMAIL PROTECTED]>
    Signed-off-by: Andrew Morton <[EMAIL PROTECTED]>
    Signed-off-by: Linus Torvalds <[EMAIL PROTECTED]>
---
 arch/um/kernel/mem.c |    3 +--
 1 files changed, 1 insertions(+), 2 deletions(-)

diff --git a/arch/um/kernel/mem.c b/arch/um/kernel/mem.c
index e85d65d..df7d662 100644
--- a/arch/um/kernel/mem.c
+++ b/arch/um/kernel/mem.c
@@ -64,8 +64,6 @@ static void setup_highmem(unsigned long highmem_start,
 
 void mem_init(void)
 {
-       max_low_pfn = (high_physmem - uml_physmem) >> PAGE_SHIFT;
-
        /* clear the zero-page */
        memset((void *) empty_zero_page, 0, PAGE_SIZE);
 
@@ -80,6 +78,7 @@ void mem_init(void)
 
        /* this will put all low memory onto the freelists */
        totalram_pages = free_all_bootmem();
+       max_low_pfn = totalram_pages;
 #ifdef CONFIG_HIGHMEM
        totalhigh_pages = highmem >> PAGE_SHIFT;
        totalram_pages += totalhigh_pages;
-
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