linux/arch/x86/mm
Jan Beulich 132978b94e x86: Fix step size adjustment during initial memory mapping
The old scheme can lead to failure in certain cases - the
problem is that after bumping step_size the next (non-final)
iteration is only guaranteed to make available a memory block
the size of what step_size was before. E.g. for a memory block
[0,3004600000) we'd have:

 iter	start		end		step		amount
 1	3004400000	30045fffff	 2M		  2M
 2	3004000000	30043fffff	64M		  4M
 3	3000000000	3003ffffff	 2G		 64M
 4	2000000000	2fffffffff	64G		 64G

Yet to map 64G with 4k pages (as happens e.g. under PV Xen) we
need slightly over 128M, but the first three iterations made
only about 70M available.

The condition (new_mapped_ram_size > mapped_ram_size) for
bumping step_size is just not suitable. Instead we want to bump
it when we know we have enough memory available to cover a block
of the new step_size. And rather than making that condition more
complicated than needed, simply adjust step_size by the largest
possible factor we know we can cover at that point - which is
shifting it left by one less than the difference between page
table level shifts. (Interestingly the original STEP_SIZE_SHIFT
definition had a comment hinting at that having been the
intention, just that it should have been PUD_SHIFT-PMD_SHIFT-1
instead of (PUD_SHIFT-PMD_SHIFT)/2, and of course for non-PAE
32-bit we can't really use these two constants as they're equal
there.)

Furthermore the comment in get_new_step_size() didn't get
updated when the bottom-down mapping logic got added. Yet while
an overflow (flushing step_size to zero) of the shift doesn't
matter for the top-down method, it does for bottom-up because
round_up(x, 0) = 0, and an upper range boundary of zero can't
really work well.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Yinghai Lu <yinghai@kernel.org>
Link: http://lkml.kernel.org/r/54945C1E020000780005114E@mail.emea.novell.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-12-23 11:39:34 +01:00
..
kmemcheck x86: Replace __get_cpu_var uses 2014-08-26 13:45:49 -04:00
amdtopology.c x86/mm/numa: Simplify some bit mangling 2013-04-10 19:06:26 +02:00
dump_pagetables.c Merge branch 'x86-mm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2014-12-10 13:59:34 -08:00
extable.c x86, extable: Switch to relative exception table entries 2012-04-20 17:22:34 -07:00
fault.c x86: mm: fix VM_FAULT_RETRY handling 2014-12-17 11:52:37 -08:00
gup.c x86/gup: Replace ACCESS_ONCE with READ_ONCE 2014-12-18 09:54:38 +01:00
highmem_32.c mm: accurately calculate zone->managed_pages for highmem zones 2013-07-03 16:07:33 -07:00
hugetlbpage.c hugetlb: restrict hugepage_migration_support() to x86_64 2014-06-04 16:53:51 -07:00
init_32.c x86: remove the Xen-specific _PAGE_IOMAP PTE flag 2014-09-23 13:36:20 +00:00
init_64.c Merge branch 'x86-vdso-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2014-12-10 14:24:20 -08:00
init.c x86: Fix step size adjustment during initial memory mapping 2014-12-23 11:39:34 +01:00
iomap_32.c x86: Use new cache mode type in mm/iomap_32.c 2014-11-16 11:04:25 +01:00
ioremap.c Merge branch 'x86-mm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2014-12-10 13:59:34 -08:00
kmmio.c x86: Delete non-required instances of include <linux/init.h> 2014-01-06 21:25:18 -08:00
Makefile x86, mpx: Add MPX-specific mmap interface 2014-11-18 00:58:53 +01:00
memtest.c x86/mm: memblock: switch to use NUMA_NO_NODE 2014-01-21 16:19:47 -08:00
mm_internal.h x86: Enable PAT to use cache mode translation tables 2014-11-16 11:04:26 +01:00
mmap.c x86/mm: Apply the section attribute to the variable, not its type 2014-09-09 07:13:39 +02:00
mmio-mod.c x86: delete __cpuinit usage from all x86 files 2013-07-14 19:36:56 -04:00
mpx.c x86 mpx: Change return type of get_reg_offset() 2014-11-19 11:54:12 +01:00
numa_32.c x86: Fix the initialization of physnode_map 2014-02-01 22:15:51 -08:00
numa_64.c x86, mm: kill numa_free_all_bootmem() 2012-11-17 11:59:47 -08:00
numa_emulation.c x86: delete __cpuinit usage from all x86 files 2013-07-14 19:36:56 -04:00
numa_internal.h x86-32, mm: Rip out x86_32 NUMA remapping code 2013-01-31 14:12:30 -08:00
numa.c Merge branch 'akpm' (patches from Andrew Morton) 2014-10-14 03:54:50 +02:00
pageattr-test.c x86: define _PAGE_NUMA by reusing software bits on the PMD and PTE levels 2014-06-04 16:53:55 -07:00
pageattr.c xen: additional features for 3.19-rc0 2014-12-16 13:23:03 -08:00
pat_internal.h x86: Use new cache mode type in memtype related functions 2014-11-16 11:04:26 +01:00
pat_rbtree.c x86: Use new cache mode type in memtype related functions 2014-11-16 11:04:26 +01:00
pat.c Merge branch 'x86-mm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2014-12-10 13:59:34 -08:00
pf_in.c x86: Eliminate various 'set but not used' warnings 2011-05-21 19:10:33 +02:00
pf_in.h
pgtable_32.c x86: Remove set_pmd_pfn 2014-09-01 10:15:31 +02:00
pgtable.c Merge branch 'x86/vdso' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip into next 2014-06-05 08:05:29 -07:00
physaddr.c x86, mm: Make DEBUG_VIRTUAL work earlier in boot 2013-01-25 16:33:22 -08:00
physaddr.h x86: split __phys_addr out into separate file 2009-09-10 11:48:55 -07:00
setup_nx.c x86: delete __cpuinit usage from all x86 files 2013-07-14 19:36:56 -04:00
srat.c x86/mm: Avoid duplicated pxm_to_node() calls 2014-02-09 15:32:31 +01:00
testmmiotrace.c x86, kmmio/mmiotrace: Fix double free of kmmio_fault_pages 2010-06-18 11:30:09 +02:00
tlb.c x86/mm: Fix sparse 'tlb_single_page_flush_ceiling' warning and make the variable read-mostly 2014-08-10 09:07:18 +02:00