path: root/arch/x86
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authorYinghai Lu <yinghai@kernel.org>2013-08-12 16:43:24 -0700
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2013-09-07 22:09:58 -0700
commit7c886152ed0b4fdfc4412f0a28ad68500b552660 (patch)
tree563ba4feb6bce61efe624aadd479972032fcce95 /arch/x86
parent344033d4079c22c92581675d7416c748d9d8201b (diff)
x86/mm: Fix boot crash with DEBUG_PAGE_ALLOC=y and more than 512G RAM
commit 527bf129f9a780e11b251cf2467dc30118a57d16 upstream. Dave Hansen reported that systems between 500G and 600G RAM crash early if DEBUG_PAGEALLOC is selected. > [ 0.000000] init_memory_mapping: [mem 0x00000000-0x000fffff] > [ 0.000000] [mem 0x00000000-0x000fffff] page 4k > [ 0.000000] BRK [0x02086000, 0x02086fff] PGTABLE > [ 0.000000] BRK [0x02087000, 0x02087fff] PGTABLE > [ 0.000000] BRK [0x02088000, 0x02088fff] PGTABLE > [ 0.000000] init_memory_mapping: [mem 0xe80ee00000-0xe80effffff] > [ 0.000000] [mem 0xe80ee00000-0xe80effffff] page 4k > [ 0.000000] BRK [0x02089000, 0x02089fff] PGTABLE > [ 0.000000] BRK [0x0208a000, 0x0208afff] PGTABLE > [ 0.000000] Kernel panic - not syncing: alloc_low_page: ran out of memory It turns out that we missed increasing needed pages in BRK to mapping initial 2M and [0,1M) when we switched to use the #PF handler to set memory mappings: > commit 8170e6bed465b4b0c7687f93e9948aca4358a33b > Author: H. Peter Anvin <hpa@zytor.com> > Date: Thu Jan 24 12:19:52 2013 -0800 > > x86, 64bit: Use a #PF handler to materialize early mappings on demand Before that, we had the maping from [0,512M) in head_64.S, and we can spare two pages [0-1M). After that change, we can not reuse pages anymore. When we have more than 512M ram, we need an extra page for pgd page with [512G, 1024g). Increase pages in BRK for page table to solve the boot crash. Reported-by: Dave Hansen <dave.hansen@intel.com> Bisected-by: Dave Hansen <dave.hansen@intel.com> Tested-by: Dave Hansen <dave.hansen@intel.com> Signed-off-by: Yinghai Lu <yinghai@kernel.org> Link: http://lkml.kernel.org/r/1376351004-4015-1-git-send-email-yinghai@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'arch/x86')
1 files changed, 2 insertions, 2 deletions
diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c
index 1f34e921977..7a5bf1b76e2 100644
--- a/arch/x86/mm/init.c
+++ b/arch/x86/mm/init.c
@@ -78,8 +78,8 @@ __ref void *alloc_low_pages(unsigned int num)
return __va(pfn << PAGE_SHIFT);
-/* need 4 4k for initial PMD_SIZE, 4k for 0-ISA_END_ADDRESS */
+/* need 3 4k for initial PMD_SIZE, 3 4k for 0-ISA_END_ADDRESS */
RESERVE_BRK(early_pgt_alloc, INIT_PGT_BUF_SIZE);
void __init early_alloc_pgt_buf(void)