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[PATCH] uml: fix LVM crash

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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 <lunz@falooley.org>
Signed-off-by: Jeff 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: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Jason Lunz 2007-03-29 01:20:31 -07:00 committed by Linus Torvalds
parent 3076212f8d
commit af84eab208
1 changed files with 1 additions and 2 deletions
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3
arch/um/kernel/mem.c
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@ -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;